text:
\section{\label{Intro} Introduction}

In Refs.~\cite{Anselmino:2005nn,Anselmino:2005ea}, we studied the
transverse single spin asymmetry $A_{UT}^{\sin(\phi_{h}-\phi_S)}$ observed
by the HERMES~\cite{Airapetian:2004tw} and COMPASS~\cite{Alexakhin:2005iw}
Collaborations in polarized SIDIS processes,
$\ell \, p\,(\mbox{\boldmath $S$}) \to \ell ^\prime \, h \, X$. The quality and amount of
the data allowed to perform a rather well constrained extraction of the
Sivers distribution function \cite{Sivers:1989cc,Sivers:1990fh} for $u$ and
$d$ quarks, assuming the existence of a symmetric and negligibly small
Sivers sea. Similar analyses and extractions were performed by other groups
\cite{Vogelsang:2005cs, Collins:2005ie, Anselmino:2005an}.
Although all these results were relevant and significant as the first
determination of the Sivers $u$ and $d$ functions, they were affected
by the low statistics of the experimental data available at that time:
in fact, COMPASS asymmetries were limited to charged hadron production,
as no hadron separation was performed, while the HERMES data were only
given for charged pion production. Recently, much higher statistics data
on the $A_{UT}^{\sin(\phi_{h}-\phi_S)}$ azimuthal asymmetries for SIDIS have
become available: in Ref.~\cite{Diefenthaler:2007rj} the HERMES Collaboration
presents neutral pion and charged kaon azimuthal asymmetries, in addition
to higher precision data on charged pion asymmetries; moreover,
Refs.~\cite{Martin:2007au,Alekseev:2008dn} show the COMPASS Collaboration
measurements for separated charged pion and kaon asymmetries,
together with some data for $K^0_S$ production.

It is then timely and natural to reconsider the analysis performed in
Ref.~\cite{Anselmino:2005ea} in order to increase our understanding of the
properties of the Sivers function. In particular, reduced error bars and
hadron separation in both the HERMES and COMPASS sets of experimental data
allow a better determination of the $u$ and $d$ flavour Sivers
distribution functions and, most importantly, a first insight into the sea
and strange contributions to the Sivers functions, namely
$\Delta^N \! f_ {\bar u/p^\uparrow}$, $\Delta^N \! f_ {\bar d/p^\uparrow}$,
$\Delta^N \! f_ {s/p^\uparrow}$ and $\Delta^N \! f_ {\bar s/p^\uparrow}$.

Our strategy is the following. First we evaluate the impact of the new data
with respect to the old data sets: as we shall explain in Section \ref{fit},
using the same unpolarized fragmentation functions as in
Refs.~\cite{Anselmino:2005nn,Anselmino:2005ea} would give a high quality fit
as far as pion asymmetries are concerned, but fails to describe the kaon data.
Instead, the use of a different, more recent set of fragmentation
functions~\cite{deFlorian:2007aj}, based on a global analysis of pion and kaon
production, will prove to be crucial to reach a successful description
of pion and kaon data simultaneously. With a simple ansatz parameterization of
the Sivers functions, we will then perform a simultaneous fit of both HERMES
and COMPASS data sets on $A^{\sin(\phi_h-\phi_S)}_{UT}$ for pion ($\pi^\pm, \,
\pi^0$) and $K^\pm$ production. We do not include in our fit the COMPASS data
on $K^0_S$ \cite{Alekseev:2008dn} as the corresponding fragmentation functions
are not so well established and can be obtained from those for $K^\pm$ only
adopting further assumptions; we shall rather estimate
$A^{\sin(\phi_h-\phi_S)}_{UT}$ for $K^0_S$, and compare it with COMPASS data,
using the Sivers functions obtained by fitting all other data sets, and
assuming exact $SU(2)$ invariance to derive the quark fragmentation functions
into $K^0_S$.

The above procedure will allow to determine the valence and sea proton Sivers
functions, which will be used to provide estimates for the analogous single
spin asymmetries that will soon be measured at JLab (operating on proton,
neutron and deuteron targets) and at COMPASS (operating on a proton target).
Notice that the JLab measurements will provide vital information on the large
$x$ behaviour of the Sivers distribution functions, yet undetermined from
present SIDIS experiments, as explained in Section~\ref{estimates}.

\section{\label{Mod} Formalism and parameterization}

The SIDIS transverse single spin asymmetry (SSA) $A^{\sin(\phi_h-\phi_S)}_{UT}$
measured by HERMES and COMPASS is defined as (see Fig.~\ref{fig:planessidis}
for the definition of the azimuthal angles)
\begin{equation}
A^{\sin (\phi_h-\phi_S)}_{UT} = \label{def-siv-asym}
2 \, \frac{\int d\phi_S \, d\phi_h \,
[d\sigma^\uparrow - d\sigma^\downarrow] \, \sin(\phi_h-\phi_S)}
{\int d\phi_S \, d\phi_h \,
[d\sigma^\uparrow + d\sigma^\downarrow]}\,,
\end{equation}
and shows the azimuthal modulation triggered by the correlation between the
nucleon spin and the quark intrinsic transverse momentum. This effect is
embodied in the Sivers distribution function $\Delta^N \! f_ {q/p^\uparrow}(x,k_\perp)$,
which appears in the number density of unpolarized quarks $q$ with intrinsic
transverse momentum $\mbox{\boldmath $k$} _\perp$ inside a transversely polarized proton
$p^\uparrow$, with three-momentum $\mbox{\boldmath $P$}$ and spin polarization vector $\mbox{\boldmath $S$}$,
\begin{eqnarray}
\hat f_ {q/p^\uparrow} (x,\mbox{\boldmath $k$}_\perp) &=& f_ {q/p} (x,k_\perp) +
\frac{1}{2} \, \Delta^N \! f_ {q/p^\uparrow}(x,k_\perp)  \;
{\mbox{\boldmath $S$}} \cdot (\hat {\mbox{\boldmath $P$}}  \times
\hat{\mbox{\boldmath $k$}}_\perp) \,,\label{sivnoi}
\end{eqnarray}
where $f_ {q/p}(x,k_\perp)$ is the unpolarized $x$ and $k_\perp$ dependent
parton distribution, and the mixed product
${\mbox{\boldmath $S$}} \cdot (\hat {\mbox{\boldmath $P$}}  \times \hat{\mbox{\boldmath $k$}}_\perp)$ explicitly gives
the azimuthal dependence mentioned above. Notice that the Sivers function
is also often denoted as $f_{1T}^{\perp q}(x, k_\perp)$ \cite{Mulders:1995dh};
this notation is related to ours by \cite{Bacchetta:2004jz}
\begin{equation}
\Delta^N \! f_ {q/p^\uparrow}(x,k_\perp) = - \frac{2\,k_\perp}{m_p} \>
f_{1T}^{\perp q}(x, k_\perp) \>. \label{rel}
\end{equation}

The ``weighting'' factor $\sin(\phi_h -\phi_S)$ in Eq.~(\ref{def-siv-asym})
is appropriately chosen to single out, among the various azimuthal dependent
terms appearing in $[d\sigma^\uparrow - d\sigma^\downarrow]$
\cite{Bacchetta:2006tn,SIDIS-general}, only the contribution of the Sivers
mechanism. By properly taking into account all intrinsic motions this
transverse single spin asymmetry can be written, at order $(k_\perp/Q)$,
as \cite{Anselmino:2005ea}
\begin{equation}
A^{\sin (\phi_h-\phi_S)}_{UT} = \label{hermesut}
\frac{\displaystyle  \sum_q \int
{d\phi_S \, d\phi_h \, d^2 \mbox{\boldmath $k$} _\perp}\;
\Delta^N \! f_{q/p^\uparrow} (x,k_\perp) \sin (\varphi -\phi_S) \;
\frac{d \hat\sigma ^{\ell q\to \ell q}}{dQ^2} \;
\; D_q^h(z,p_\perp) \sin (\phi_h -\phi_S) }
{\displaystyle \sum_q \int {d\phi_S \,d\phi_h \, d^2 \mbox{\boldmath $k$} _\perp}\;
f_{q/p}(x,k _\perp) \; \frac{d \hat\sigma ^{\ell q\to \ell q}}{dQ^2} \;
 \; D_q^h(z,p_\perp) } \> \cdot
\end{equation}
$\phi_S$ and $\phi_h$ are the azimuthal angles identifying the
directions of the proton spin $\mbox{\boldmath $S$}$ and of the outgoing hadron $h$
respectively, while $\varphi$ defines the direction of the incoming
(and outgoing) quark transverse momentum,
$\mbox{\boldmath $k$}_\perp$ = $k_\perp(\cos\varphi, \sin\varphi,0)$,
as shown in Fig.~\ref{fig:planessidis};
$\frac{d \hat\sigma ^{\ell q\to \ell q}}{dQ^2}$ is the unpolarized
cross section for the elementary scattering  $\ell q\to \ell q$,
\begin{equation}
\frac{d \hat\sigma^{\ell q\to \ell q}}{d Q^2} = e_q^2 \,
\frac{2\pi \alpha^2}{\hat s^2}\,
\frac{\hat s^2+\hat u^2}{Q^4}\;,
\label{part-Xsec}
\end{equation}
where $\hat s$, $\hat t = -Q^2$ and $\hat u$ are the partonic Mandelstam
invariants.

Finally, $D_q^h(z,p_\perp)$ is the fragmentation function describing the
hadronization of the final quark $q$ into the detected hadron $h$ with
momentum $\mbox{\boldmath $P$}_h$ (see Fig.~\ref{fig:planessidis}); $h$ carries, with respect
to the fragmenting quark, a light-cone momentum fraction $z$ and a transverse
momentum $\mbox{\boldmath $p$}_\perp$.
\begin{figure}[t]
\begin{center}
\scalebox{0.26}{\input{planessidis.pstex_t}}
\caption{\small Kinematics of the SIDIS process in the $\gamma^* p$ center of
mass frame.}
\label{fig:planessidis}
\end{center}
\end{figure}

In our analysis we shall consider $u$, $d$ and $s$ flavours for quarks and
antiquarks. The Sivers function is parameterized in terms of the unpolarized
distribution function, as in Ref.~\cite{Anselmino:2005ea}, in the following
factorized form:
\begin{equation}
\Delta^N \! f_ {q/p^\uparrow}(x,k_\perp) = 2 \, {\cal N}_q(x) \, h(k_\perp) \,
f_ {q/p} (x,k_\perp)\; , \label{sivfac}
\end{equation}
with
\begin{eqnarray}
&&{\cal N}_q(x) =  N_q \, x^{\alpha_q}(1-x)^{\beta_q} \,
\frac{(\alpha_q+\beta_q)^{(\alpha_q+\beta_q)}}
{\alpha_q^{\alpha_q} \beta_q^{\beta_q}}\; ,
\label{siversx} \\
&&h(k_\perp) = \sqrt{2e}\,\frac{k_\perp}{M_{1}}\,e^{-{k_\perp^2}/{M_{1}^2}}\; ,
\label{siverskt}
\end{eqnarray}
where $N_q$, $\alpha_q$, $\beta_q$ and $M_1$ (GeV/$c$) are free parameters
to be determined by fitting the experimental data. Since $h(k_\perp) \le 1$ for
any $k_\perp$ and $|{\cal N}_q(x)| \le 1$ for any $x$ (notice that we allow the
constant parameter $N_q$ to vary only inside the range $[-1,1]$), the
positivity bound for the Sivers function,
\begin{equation}
\frac{|\Delta^N\!f_ {q/p^\uparrow}(x,k_\perp)|}{2 f_ {q/p} (x,k_\perp)}\le 1\>,
\label{pos}
\end{equation}
is automatically fulfilled. We adopt the usual (and convenient) Gaussian
factorization for the unpolarized distribution and fragmentation functions:
 %
\begin{equation}
f_{q/p}(x,k_\perp) = f_q(x) \, \frac{1}{\pi \langlek_\perp^2\rangle} \,
e^{-{k_\perp^2}/{\langlek_\perp^2\rangle}}
\label{partond}
\end{equation}
and
\begin{equation}
D_q^h(z,p _\perp) = D_q^h(z) \, \frac{1}{\pi \langle p_\perp^2\rangle}
\, e^{-p_\perp^2/\langle p_\perp^2\rangle} \>,
\label{partonf}
\end{equation}
with the values of $\langle k_\perp^2\rangle$ and $\langle p_\perp^2\rangle$
fixed to the values found in Ref.~\cite{Anselmino:2005nn} by analysing the
Cahn effect in unpolarized SIDIS:
\begin{equation}
\langlek_\perp^2\rangle   = 0.25  \;({\rm GeV}/c)^2 \quad\quad\quad
\langle p_\perp^2\rangle  = 0.20 \;({\rm GeV}/c)^2 \>.
\label{ktpar}
\end{equation}
Notice that the Gaussian distributions limit the effective action of
intrinsic motion to $k_\perp \mathrel{\rlap{\lower4pt\hbox{\hskip1pt$\sim$}}\raise1pt\hbox{$<$}} \sqrt{\langlek_\perp^2\rangle}$ and
$p_\perp \mathrel{\rlap{\lower4pt\hbox{\hskip1pt$\sim$}}\raise1pt\hbox{$<$}} \sqrt{\langle p_\perp^2\rangle}$, which is the region of
validity of the TMD factorized expressions in Eq.~(\ref{hermesut}),
$P_T\simeq k_\perp \simeq \Lambda _{\rm QCD} \ll
Q$~\cite{Ji:2004wu,Ji:2004xq,Ji:2006br}.

The parton distribution functions (PDF) $f_{q}(x)$ and the fragmentation
functions (FF) $D_q^h(z)$ also depend on $Q^2$ via the usual QCD evolution,
which will be taken into account, at leading order (LO), in all our computations.

Before fitting the data on the Sivers asymmetries a few comments on the quark
hadronization are necessary. While most of the available sets of fragmentation
functions describe rather well the pion multiplicities observed at HERMES,
many of them fail to reproduce the kaon multiplicities in SIDIS production.
The main reason is the role of the strange quarks, which is often not well
established: for example, one expects that $K^+$ mesons can be abundantly
produced by $\bar s$ quarks, via creation from the vacuum of a light $u \bar u$
pair, rather than by $u$ quarks, via creation from the vacuum of a heavier
$s \bar s$ pair. Such a feature is particularly emphasized in the set recently
obtained by de Florian, Sassot, Stratmann (DSS) \cite{deFlorian:2007aj},
which has $D_{\bar s}^{K^+}(z) \, \gg \, D_{u}^{K^+}(z)$ over the whole $z$
range. This is shown in Fig.~\ref{fig:ffs}, where the LO DSS fragmentation
functions (solid lines) are compared with those proposed by Kretzer
(KRE)~\cite{Kretzer:2000yf} (dashed lines) and by Hirai, Kumano, Nagai
and Sudoh (HKNS)~\cite{Hirai:2007cx} (dotted lines). The DSS set, which is
determined by fitting all presently available multiplicity measurements, both
for pions and kaons, is indeed the most suitable for our purposes.

This can also be seen in a more quantitative way. We know that Kretzer's and
other commonly adopted sets of fragmentation functions are able
to describe pion production data, as shown, for instance, in Fig.~4 of
Ref.~\cite{deFlorian:2007aj}. However, Fig.~13 of Ref.~\cite{deFlorian:2007aj}
shows instead that Kretzer fragmentation functions fail to reproduce charged
kaon SIDIS multiplicities, and might not be adequate to reconstruct transverse
single spin asymmetries corresponding to kaon production. In fact, by using
the Kretzer set for our fit, we would not be able to describe the kaon
asymmetry data: to be more precise, we would obtain $\chi ^2/d.o.f. \equiv
\chi^2_{dof} \simeq 1$ for pions but $\chi^2_{dof}\simeq 4$ for kaon
production asymmetries. Estimates for $K^\pm$ asymmetries were presented in
Ref. \cite{Anselmino:2005ea} and the inadequacy of the Kretzer fragmentation
functions was pointed out in several talks (see, for example, Ref. \cite{talk}).
The same conclusion has been confirmed, very recently, in
Ref. \cite{Arnold:2008ap}.

Let us now turn to the experimental data on kaon and pion Sivers azimuthal
asymmetries measured by the HERMES Collaboration~\cite{Diefenthaler:2007rj}.
The single spin asymmetry corresponding to $K^+$ production is, as a matter
of fact, much larger than the analogous asymmetry for $\pi^+$. Although one
could naively expect, on the basis of $u$ quark dominance, that $K^+$ and
$\pi^+$ asymmetries should be roughly the same, the presence of a large
$D_{\bar s}^{K^+}$ FF can help to understand the ``puzzle'' of the $K^+$
asymmetry. Indeed, if a non-negligible $\bar s$ Sivers function exists, then
its action combined with a large $D_{\bar s}^{K^+}$ fragmentation function
can give rise to a significant difference between $K^+$ and $\pi^+$ Sivers
asymmetries.
\begin{figure}[t]
\vskip -24pt
\includegraphics[width=0.62 \textwidth,bb= 10 140 540 660,angle=-90]
{fragmentation_functions.ps}
\caption{\label{fig:ffs}
The LO unpolarized fragmentation functions for $u$, $d$ and $s$ flavours, at
$Q^2 = 2.4$ (GeV/$c)^2$, as given
by Kretzer \cite{Kretzer:2000yf} (dashed lines), by Hirai, Kumano, Nagai and
Sudoh \cite{Hirai:2007cx} (dotted lines) and by de Florian, Sassot and
Stratmann~\cite{deFlorian:2007aj} (solid lines). We show the fragmentation
functions for $\pi^+$ in the upper panel, and for $K^+$ production in the lower
panel. Notice that the fragmentation function describing the probability of a
$K^+$ originating from an $\bar s$ quark is much larger than that associated
to a $K^+$ from a $u$ quark, over the whole $z$ range. The two solid curves in
the central upper plot correspond to $zD_{d}^{\pi^+} = zD_{\bar u}^{\pi^+}$
(upper line) and $zD_{s}^{\pi^+} = zD_{\bar s}^{\pi+}$ (lower line).}
\end{figure}

\section{Fit of SIDIS data and extraction of Sivers functions}\label{fit}

The recent SIDIS experimental data on Sivers asymmetries for pion
\textit{and kaon} production give us the opportunity to study sea-quark Sivers
functions for $\bar u$, $\bar d$, $s$ and $\bar s$ quarks. The $u$ and $d$ quark
Sivers functions alone were already studied in Ref. \cite{Anselmino:2005ea}; in
the present analysis we will be able to improve the extraction of these
functions and to present first estimates of the sea-quark Sivers functions.

In order to evaluate the significance of the sea-quark Sivers contributions we
first perform a fit of the SIDIS data using flavour independent ratios of the
sea-quark Sivers functions with the corresponding unpolarized PDFs: that is,
for $\bar u$, $\bar d$, $s$ and $\bar s$ flavours we attempt an ``unbroken sea"
ansatz:
\begin{eqnarray}
&&\Delta^N \! f_ {q/p^\uparrow}(x,k_\perp) = 2 \, {\cal N}_{sea}(x) \, h(k_\perp) \,
f_ {q/p} (x,k_\perp)\; , \nonumber \\
&&{\cal N}_{sea}(x) =  N_{sea} \, x^{\alpha_{sea}}(1-x)^{\beta_{sea}}
\,\frac{(\alpha_{sea}+\beta_{sea})^{(\alpha_{sea}+\beta_{sea})}}
{\alpha_{sea}^{\alpha_{sea}} \beta_{sea}^{\beta_{sea}}}\; ,
\label{siverskt_sea}
\end{eqnarray}
where $N_{sea}, \alpha_{sea}, \beta_{sea}$ are the same for all sea quarks,
$q = \bar u$, $\bar d$, $s$ and $\bar s$.

As the SIDIS data from HERMES and COMPASS have a limited coverage in $x$,
typically $x < 0.3-0.4$, the experimental asymmetries we are fitting contain
very little information on the large $x$ tail of the Sivers functions.
In fact, our previous analysis of Ref.~\cite{Anselmino:2005ea} showed that
the parameters $\beta_{u}$ and $\beta_{d}$ as determined by MINUIT best fit
procedure are affected by very large errors. Therefore, as a first attempt,
we assume the same value of $\beta$ for all Sivers functions, setting
$\beta_{sea} = \beta_{u} = \beta_{d} \equiv \beta$.

Thus for the ``unbroken sea" ansatz we have 8 free parameters:
\begin{eqnarray}
&& N_u \quad\quad\quad  N_d  \quad\quad\quad  N_{sea}
\nonumber \\
&& \alpha_u \quad\quad\quad \,\alpha_d \quad\quad\quad \;\alpha_{sea} \\
&& \beta   \quad\quad\quad\,\,\, M_1\;({\rm GeV}/c) \>. \nonumber
\label{par_unbroken}
\end{eqnarray}

For the purposes of our fit, we use the unpolarized parton distribution
functions $f_q(x,Q^2)$ as given in Ref.~\cite{Gluck:1998xa} (GRV98LO) and
the fragmentation functions $D_q^h(z,Q^2)$ as given in
Ref.~\cite{deFlorian:2007aj} (DSS) -- all evolved to the appropriate
$Q^2$ values -- with the additional $k_\perp$ Gaussian dependences of
Eqs.~(\ref{partond})-(\ref{ktpar}). While the choice of the DSS
fragmentation functions is the one which best describes the large
asymmetries observed for $K^+$, the use of different sets of distribution
functions, including the most recent analysis of $s$ quark distributions
from HERMES \cite{Airapetian:2008qf},
would not affect our results significantly.
For the Sivers functions,
we use the functional forms of Eqs.~(\ref{sivfac})-(\ref{siverskt}).
Notice that the (unknown) $Q^2$ evolution of these functions is assumed to be
the same as for the unpolarized PDFs, $f_q(x,Q^2)$.

By fitting simultaneously pion and kaon production data from
HERMES~\cite{Diefenthaler:2007rj} and COMPASS~\cite{Martin:2007au}
we obtain an acceptable overall description of the experimental data, with
$\chi^2_{dof} = 1.16$. The new experimental data give clear indications of the
need of a non negligible sea-quark Sivers function, with
$N_{sea} = -0.13 \pm 0.03$ sensitively different from zero.
Although the total $\chi^2_{dof}$ is definitely good, a more careful
examination of the results shows that while we achieve a perfect description
of the $\pi^+$ production data at HERMES~\cite{Diefenthaler:2007rj}, with
$\chi^2 \simeq 1$ per data point, the description of kaon production data is
rather poor, with $\chi^2 \simeq 3$ per data point for $K^+$ production at
HERMES~\cite{Diefenthaler:2007rj}. This indicates that the ``unbroken sea"
ansatz fails to reproduce the differences between pion and kaon production,
and clearly suggests the need of a parameterization which should allow for a
more structured flavour dependence of the sea-quark Sivers functions.

Including four new functions in our analysis would result in a substantial
growth of the number of parameters and would consequently limit
the usefulness of our parameterization.
To keep the number of parameters under control, we define a
simple ``broken sea" ansatz by introducing four free parameters,
$N_{\bar u}$, $N_{\bar d}$, $N_{s}$, and $N_{\bar s}$ which give different sizes
to the sea-quark Sivers functions, while keeping the same functional forms
($\alpha_{\bar u} = \alpha_{\bar d} = \alpha_{s} = \alpha_{\bar s} \equiv
\alpha_{sea}$ and $\beta_{sea} = \beta_{u} = \beta_{d} \equiv \beta$).
For the ``broken sea" ansatz fit we then have 11 parameters:
\begin{eqnarray}
&& N_u \quad\quad\quad  N_d \quad\quad\quad  N_s
\nonumber \\
&& N_{\bar u} \quad\quad\quad  N_{\bar d} \quad\quad\quad  N_{\bar s}
\nonumber \\
&& \alpha_u \quad\quad\quad \,\alpha_d \quad\quad\quad \;\alpha_{sea} \label{par_broken}\\
&& \beta   \quad\quad\quad\,\,\, M_1\;({\rm GeV}/c) \>. \nonumber
\end{eqnarray}

The results we obtain for these parameters by fitting simultaneously the four
experimental data sets on $A_{UT}^{\sin(\phi_h-\phi_S)}$, corresponding to
pion and kaon production at HERMES~\cite{Diefenthaler:2007rj} and
COMPASS~\cite{Martin:2007au}, are presented in Table~\ref{fitpar_sivers},
together with the corresponding errors, estimated according to the procedure
outlined in Appendix \ref{stat}. The fit performed under the ``broken sea"
ansatz shows a remarkable improvement, especially concerning the description
of kaon data. We now obtain $\chi^2 = 1.20$ per data point for $K^+$
production at HERMES~\cite{Diefenthaler:2007rj}, while for pions we have
$\chi^2 = 0.94$ per data point, and a total $\chi^2_{dof} = 1.00$.
In Table II we show the $\chi^2$ per data point for pion and kaon production
at HERMES and COMPASS, both for the "unbroken sea" and "broken sea" ansatze
and adopting the Kretzer and DSS FF sets. Notice that these values refer
to the asymmetries as a function of $x$.

The quality of our results is shown in Figs.~\ref{fig:hermes} and
\ref{fig:compass} where our best fit to the SSA is compared with the
experimental data from Refs.~\cite{Diefenthaler:2007rj}~and~\cite{Martin:2007au}:
the SSAs are plotted as a function of one variable at a time, either $x$ or $z$
or $P_T$, while an integration over the other variables has been performed
consistently with the cuts of the corresponding experiment.
\begin{table}[t]
\caption{
Best values of the free parameters for the ``broken sea" ansatz,
Eq.~(\ref{par_broken}).
Notice that the statistical errors reported in this table are not the errors given by
MINUIT. As the parameters are strongly correlated, we determine them
according to the procedure explained in Appendix A.
The significant fluctuations in our results are shown by the shaded areas in
Figs.~\ref{fig:hermes} and \ref{fig:compass}.
\label{fitpar_sivers}}
\begin{center}
\begin{tabular}{l l l}
\hline
\hline
\noalign{\vspace{3pt}}
\multicolumn{3}{ c }{~~~~~~~~~~~~~~~~~~$\chi^2/d.o.f. =
1.00$~~~~~~~~~~~~~~~~~~~~}\\
\noalign{\vspace{3pt}}
\hline
~&~&~\\
~~~$N_{u} = 0.35 ^{+ 0.08}_{-0.08} $ \hspace*{1cm} &
~~~$N_{d} = -0.90 ^{+ 0.43}_{-0.10} $ &
~~~$N_{s} = -0.24 ^{+ 0.62}_{-0.50} $~~ \\
~~~$N_{\bar u} =  0.04 ^{+ 0.22}_{-0.24} $&
~~~$N_{\bar d} =  -0.40 ^{+ 0.33}_{-0.44}$&
~~~$N_{\bar s} =  1 ^{+0}_{-0.0001}$ \\
~~~$\alpha _u = 0.73 ^{+ 0.72}_{-0.58}$ &
~~~$\alpha_d = 1.08 ^{+ 0.82}_{-0.65}$  &
~~~$\alpha_{sea} = 0.79 ^{+ 0.56}_{-0.47}$ \\
~~~$\beta \;\;= 3.46 ^{+ 4.87}_{-2.90}$ &
~~~$M_1^2 = 0.34 ^{+ 0.30}_{-0.16}$ (GeV/$c)^2$~  &
~~~~~ \\
~&~&~\\
\hline
\hline
\end{tabular}
\end{center}

\end{table}
\begin{table}[b]
\caption{$\chi^2$ per data point for pion and kaon production at HERMES and
COMPASS, both for the ``unbroken sea" and ``broken sea" ansatze, and adopting the
Kretzer and DSS FF sets. $x$ dependent data, integrated over $z$ and $P_T$,
are considered here.}
\vspace*{6pt}
\begin{ruledtabular}
\begin{tabular}{ccccccc}
\noalign{\vspace{3pt}}
  Experiment & observed hadron & n. of data points & \multicolumn{4}{c} {$\chi^2$ per data point} \\
\noalign{\vspace{3pt}}
\colrule
\noalign{\vspace{3pt}}
 & & & \multicolumn{2}{c}{Kretzer} & \multicolumn{2}{c}{DSS} \\
\noalign{\vspace{3pt}}
\cline{4-7}
\noalign{\vspace{3pt}}
 & & & \multicolumn{1}{c}{unbroken sea} &
 \multicolumn{1}{c}{broken sea} &  \multicolumn{1}{c}{unbroken sea} &
 \multicolumn{1}{c}{broken sea} \\
\noalign{\vspace{3pt}}
\cline{1-7}
\noalign{\vspace{3pt}}
          &  $\pi^+$  & 5 &  $0.65$  &  $0.53$  &  $0.57$  & $0.56$ \\
\noalign{\vspace{1pt}}
          &  $\pi^-$  & 5 &  $2.67$  &  $2.64$  &  $1.60$  & $1.62$ \\
\noalign{\vspace{1pt}}
  HERMES  &  $\pi^0$  & 5 &  $0.48$  &  $0.46$  &  $0.47$  & $0.43$ \\
\noalign{\vspace{1pt}}
          &  $K^+$    & 5 &  $6.14$  &  $5.71$  &  $3.87$  & $2.11$ \\
\noalign{\vspace{1pt}}
          &  $K^-$    & 5 &  $0.79$  &  $0.80$  &  $0.73$  & $0.69$ \\
\noalign{\vspace{5pt}}
\cline{1-7}
\noalign{\vspace{5pt}}
          &  $\pi^+$    & 9 &  $0.65$  &  $0.57$  &  $0.39$  & $0.64$ \\
\noalign{\vspace{1pt}}
  COMPASS &  $\pi^-$    & 9 &  $0.83$  &  $0.55$  &  $0.49$  & $0.70$ \\
\noalign{\vspace{1pt}}
          &  $K^+$      & 9 &  $0.84$  &  $0.75$  &  $0.78$  & $0.57$ \\
\noalign{\vspace{1pt}}
          &  $K^-$      & 9 &  $1.47$  &  $1.34$  &  $1.17$  & $1.36$ \\
\noalign{\vspace{3pt}}
\end{tabular}
\end{ruledtabular}
\label{rtab}
\end{table}
\begin{figure}[t]
\begin{center}
\includegraphics[width=0.35\textwidth,bb= 10 140 540 660,angle=-90]
{hermes_sivers_pi0.ps} \hskip 2.85cm
\includegraphics[width=0.35\textwidth,bb= 10 140 540 660,angle=-90]
{hermes_sivers_k0.ps}
\caption{\label{fig:hermes}
The results obtained from our simultaneous fit of the SIDIS
$A_{UT}^{\sin{(\phi_h-\phi_S)}}$ Sivers asymmetries (solid lines) are
compared with HERMES experimental data \cite{Diefenthaler:2007rj} for pion
and kaon production (left and right panel, respectively). The shaded area
corresponds to the statistical uncertainty of the parameters, see
Appendix~\ref{stat} for further details. For completeness, we also show the
$K_S^0$ asymmetry, not measured at HERMES, which is the result of a
computation based on our extracted Sivers function and the assumed
fragmentation functions of Eq.~(\ref{D0SFF}).}
\end{center}
\end{figure}
\begin{figure}[t]
\begin{center}
\includegraphics[width=0.35\textwidth,bb= 10 140 540 660,angle=-90]
{compass_sivers_pi0.ps} \hskip 2.85cm
\includegraphics[width=0.35\textwidth,bb= 10 140 540 660,angle=-90]
{compass_sivers_k0.ps}
\caption{\label{fig:compass}
The results obtained from our fit (solid lines) are compared with the COMPASS
measurements of $A_{UT}^{\sin{(\phi_h-\phi_S)}}$ for pion (left panel)
and kaon (right panel) production \cite{Martin:2007au} off a deuteron target.
The shaded area corresponds to the statistical uncertainty of the parameters,
as explained in Appendix~\ref{stat}. The $\pi^0$ asymmetry, not measured at
COMPASS, is the result of a computation based on our extracted Sivers functions.
Also the $K_S^0$ asymmetry, although compared with data~\cite{Alekseev:2008dn},
is not a best fit, but the result of our computation, using the assumed
fragmentation functions of Eq.~(\ref{D0SFF}).}
\end{center}
\end{figure}
\begin{figure}
\begin{center}
\includegraphics[width=0.55\textwidth,bb= 10 150 580 660,angle=-90]
{hermes_sivers_kaons_compare.ps} \hskip 2.85cm
\caption{\label{fig:dflo-kretz}
The results obtained from our fit using the kaon fragmentation functions
as given by de Florian {\it et al.} in Ref.~\cite{deFlorian:2007aj} (solid
lines) are compared with the results we would find by using the
KRE~\cite{Kretzer:2000yf}(dotted lines) and HKNS~\cite{Hirai:2007cx}
(dashed lines) sets of fragmentation functions.}
\end{center}
\end{figure}
\begin{figure}[t]
\includegraphics[width=0.7\textwidth,bb= 10 40 540 740,angle=0]
{sivers_functions.ps}
\caption{\label{fig:sivers}
The Sivers distribution functions for $u$, $d$ and $s$ flavours, at the scale
$Q^2=2.4$ (GeV$/c)^2$, as determined
by our simultaneous fit of HERMES and COMPASS data (see text for details).
On the left panel, the first moment $x\,\Delta^N \! f^{(1)}(x)$,
Eq.~(\ref{mom}), is shown as a function of $x$ for each flavour, as indicated.
Similarly, on the right panel, the Sivers distribution
$x\,\Delta^N \! f(x,k_\perp)$
is shown as a function of $k_\perp$ at a fixed value of $x$ for each flavour, as
indicated. The highest and lowest dashed lines show the positivity limits
$|\Delta^N \! f| = 2f$.
}
\end{figure}
\begin{figure}[t]
\includegraphics[width=0.60\textwidth,bb= 10 140 580 660,angle=-90]
{sivers_functions_valence_vs_como_log.ps}
\caption{\label{fig:sivers-como}
The Sivers distribution functions for $u$ and $d$ flavours, at the scale
$Q^2=2.4$ (GeV$/c)^2$, as determined
by our present fit (solid lines), are compared with those of our previous fit
\cite{Anselmino:2005ea} of SIDIS data (dashed lines), where $\pi^0$ and kaon
productions were not considered and only valence quark contributions were taken
into account. This plot clearly shows that the Sivers functions previously
found are consistent, within the statistical uncertainty bands, with the Sivers
functions presently obtained.
}
\end{figure}
In order to check the dependence on the set of unpolarized PDF's adopted,
we have also performed the fit by using the CTEQ6L~\cite{Pumplin:2002vw}
and the MRST01LO~\cite{Martin:2002dr} sets; in both cases,
the quality of the fit and the central-value results for the asymmetries are
so similar to those obtained with the GRV98LO set that they would be hardly
distinguishable in Figs.~\ref{fig:hermes} and~\ref{fig:compass}.

The shaded areas in Figs.~\ref{fig:hermes} and \ref{fig:compass}
(and in all subsequent figures where they are shown) represent statistical
uncertainties and correspond to a 95.45\% Confidence Level (CL): they are
determined according to the procedure described in Appendix~\ref{stat}.
Notice that further uncertainties of theoretical nature, intrinsic to
our phenomenological approach, are present and might widen the size of the
statistical bands. However, these are very difficult to assess: it suffices
to recall that our analysis is performed assuming a simple factorized $k_\perp$
dependence in Eqs.~(\ref{sivfac}), (\ref{partond}) and (\ref{partonf}), that
the actual $Q^2$ evolution of the Sivers function is unknown and that
uncertainties in the fragmentation functions have not been taken into account.
The functional form for the $x$-dependence of the Sivers functions used
in the fit, Eq.~(\ref{siversx}), is a simple one and more structured dependences
might allow better fits, with the statistical shaded areas covering better the
experimental errors of the data. At this stage, considering the available
experimental information and the remaining theoretical issues to be clarified,
we do not think that further refinements of our analysis would be meaningful.

Notice that in Fig.~\ref{fig:compass} we also show the results for $\pi^0$ at
COMPASS, for which no data is so far available, computed using our extracted
Sivers functions as given in Table~\ref{fitpar_sivers}. Similarly we have
computed $A_{UT}^{\sin(\phi_h-\phi_S)}$ for $K^0_S$ production at HERMES and
COMPASS and show them respectively in Figs.~\ref{fig:hermes} and \ref{fig:compass}.
As the $K^0_S$ is an equal mixture of $K^0 = d\bar s$ and $\bar K^0 = \bar ds$,
we have assumed isospin invariance, writing the $K^0_S$ FFs in terms of the
$K^+$ ones -- which are taken from Ref.~\cite{deFlorian:2007aj} -- as:
\begin{eqnarray}
&& D_d^{K^0_S} = D_{\bar d}^{K^0_S} = \frac 12 \left[ D_u^{K^+}
+ D_{sea}^{K^+} \right] \nonumber \\
&& D_{\bar s}^{K^0_S} = D_s^{K^0_S} = \frac 12 \left[ D_{\bar s}^{K^+}
+ D_{sea}^{K^+} \right] \label{D0SFF} \\
&& D_{u}^{K^0_S} = D_{\bar u}^{K^0_S} = D_{sea}^{K^+} \equiv
D_{d}^{K^+} = D_{\bar u}^{K^+} = D_{s}^{K^+} = D_{\bar d}^{K^+} \,. \nonumber
\end{eqnarray}
Our computation of the $K^0_S$ asymmetry at COMPASS can be compared with the
available data~\cite{Alekseev:2008dn}, as shown in the upper-right plots of
Fig.~\ref{fig:compass}. Notice that these curves, contrary to the others in
the same figure, are not best fits, but a simple estimate, based on the
extracted Sivers functions and the adopted fragmentation functions of
Eq.~(\ref{D0SFF}).

In Fig.~\ref{fig:dflo-kretz}, our results, obtained using the kaon fragmentation
functions as given by de Florian {\it et al.} in Ref.~\cite{deFlorian:2007aj}
(solid lines), are compared with the best fit we would find by using the
KRE~\cite{Kretzer:2000yf} (dotted lines) and HKNS~\cite{Hirai:2007cx} (dashed
lines) sets of fragmentation functions. It is clear that the use of the new --
strange-quark sensitive -- fragmentation functions yields a much better
agreement with the experimental measurements of the SIDIS azimuthal
asymmetries for kaon production.

The Sivers functions generated by our best fit procedure are presented, at the scale $Q^2=2.4$ (GeV$/c)^2$, in
Fig.~\ref{fig:sivers}, where we plot, on the left panel, the first
$\mbox{\boldmath $k$}_\perp$ moment defined as
\begin{equation}
\Delta^N \! f_{q/p^\uparrow}^{(1)}(x) \equiv \int d^2 \, \mbox{\boldmath $k$}_\perp \,\frac{k_\perp}{4m_p}
\, \Delta^N \! f_{q/p^\uparrow}(x, k_\perp) = - f_{1T}^{\perp (1) q}(x) \>, \label{mom}
\end{equation}
and, on the right panel, the $k_\perp$ dependence of
$\Delta^N \! f_{q/p^\uparrow}$ at a fixed value of $x=0.1$. The highest and lowest
dashed lines show the positivity limits $|\Delta^N \! f| = 2f$.

Our results both confirm previous conclusions on the $u$ and $d$ Sivers
distributions and, despite the still large uncertainties
(see Table~\ref{fitpar_sivers}), offer some new clear information about
the so far unknown sea-quark Sivers functions. Let us comment in detail:
\begin{itemize}
\item
The HERMES data on kaon asymmetries, surprisingly large for $K^+$, cannot be
explained without a sea-quark Sivers distribution. In particular, we
definitely find
\begin{equation}
\Delta^N \! f_{\bar s/p^\uparrow} > 0
\label{func_brokens}
\end{equation}
and confirm the previous findings for valence flavours
\cite{Anselmino:2005ea, Vogelsang:2005cs, Collins:2005ie, Anselmino:2005an},
\begin{equation}
\Delta^N \! f_{u/p^\uparrow} > 0 \quad\quad\quad  \Delta^N \! f_{d/p^\uparrow} < 0 \>.
\label{func_brokenv}
\end{equation}
There are simple reasons for the above results. The Sivers
distribution function for $\bar s$ quarks turns out to be definitely positive,
due to the large positive value of $A_{UT}^{\sin(\phi_h-\phi_S)}$ for $K^+$;
notice that the value of $N_{\bar s}$ saturates the positivity bound
$|N_q| \leq 1$. Similarly, the positive sign of $\Delta^N \! f_{u/p^\uparrow}$ is,
essentially, driven by the positive $\pi^+$ and $K^+$ SSAs and the opposite sign of
$\Delta^N \! f_{d/p^\uparrow}$ by the small SSA measured by COMPASS on a deuteron
target. The $u$ and $d$ Sivers functions are also predicted to be opposite
in the large $N_c$ limit~\cite{Pobylitsa:2003ty} and in chiral models
\cite{Drago:2005gz}.

\item
The Sivers functions for $\bar u$, $\bar d$ and $s$ quarks, instead, turn out
to have much larger uncertainties; even the sign of the $\bar u$ and $s$
Sivers functions is not fixed by available data, while $\Delta^N \!
f_{\bar d/p^\uparrow}$ appears to be negative.
This could be consistent with a positive contribution from
$u$ quarks, necessary to explain the large $K^+$ asymmetry, which is
decreased,
for $\pi^+$, by a negative $\bar d$ contribution.
One might expect correlated Sivers functions for $s$
and $\bar s$ quarks: we have actually checked that choosing $\Delta^N \!
f_{s/p^\uparrow} = \pm \Delta^N \! f_{\bar s/p^\uparrow}$ slightly worsens the
$\chi^2_{dof}$ (from 1 up to about 1.1), but still leads to a reasonable fit.

\item
We notice that the Burkardt sum rule \cite{Burkardt:2004ur}
\begin{equation}
\sum_a \int dx \, d^2 \mbox{\boldmath $k$}_\perp \, \mbox{\boldmath $k$}_\perp \, f_{a/p^\uparrow}(x, \mbox{\boldmath $k$}_\perp)
\equiv  \sum_a \, \langle \mbox{\boldmath $k$}_\perp^a \rangle = 0 \>, \label{bsr}
\end{equation}
where, from Eqs. (\ref{sivnoi}) and (\ref{mom}),
\begin{eqnarray}
\langle \mbox{\boldmath $k$}_\perp^a \rangle &=& \left[ \frac{\pi}{2}\int_0^1 \!\! dx
\int_0^\infty  \!\! dk_\perp \,k_\perp^2 \, \Delta^N \! f_{a/p^\uparrow}(x,k_\perp) \right]
(\mbox{\boldmath $S$} \times \hat{\mbox{\boldmath $P$}})  \nonumber \\
&=& m_p \int_0^1 \!\! dx  \, \Delta^N \! f_{q/p^\uparrow}^{(1)}(x)
\, (\mbox{\boldmath $S$} \times \hat{\mbox{\boldmath $P$}}) \equiv \langle k_\perp^a \rangle \,
(\mbox{\boldmath $S$} \times \hat{\mbox{\boldmath $P$}})\,, \label{bsr3}
\end{eqnarray}
is almost saturated by $u$ and $d$ quarks alone at $Q^2 = 2.4$ (GeV$/c)^2$:
\begin{equation}
\langle k_\perp^u \rangle + \langle k_\perp^d \rangle =
-17^{+37}_{-55} \>\> ({\rm MeV}/c)\quad\quad\quad
\langle k_\perp^{\bar u} \rangle + \langle k_\perp^{\bar d} \rangle
+\langle k_\perp^s \rangle + \langle k_\perp^{\bar s} \rangle =
-14^{+43}_{-66} \>\> ({\rm MeV}/c). \label{bsr-u+d-sea}
\end{equation}
The individual contributions for quarks are:
\begin{eqnarray}
\langle k_\perp^u \rangle &=& 96^{+60}_{-28} \>\>
({\rm MeV}/c)\quad\quad\quad
\langle k_\perp^d \rangle \, = -113^{+45}_{-51} \>\>
({\rm MeV}/c)\nonumber \\
\langle k_\perp^{\bar u} \rangle &=& \>\> 2^{+24}_{-11} \>\>
({\rm MeV}/c)\quad\quad\quad
\langle k_\perp^{\bar d} \rangle \, = \,\,\> -28^{ +20}_{-60} \>\>
({\rm MeV}/c)\label{bsr-single} \\
\langle k_\perp^{s} \rangle &=& \!\! -4^{+11}_{-15} \>\>
({\rm MeV}/c)\quad\quad\quad
\langle k_\perp^{\bar s} \rangle \, = \quad\>\, 17^{+30}_{-8} \
({\rm MeV}/c)\>, \nonumber
\end{eqnarray}
thus leaving little room for a gluon Sivers function,
\begin{equation}
-10 \le \langle k_\perp^g \rangle \le 48 \ ({\rm MeV}/c)\>, \label{bsr-g}
\end{equation}
in agreement with other
similar results \cite{Anselmino:2006yq, Brodsky:2006ha}. The statistical uncertainties
in the values given above have been computed as explained at the end of
Appendix A.

\item
In Fig.~\ref{fig:sivers-como} we compare the $u$ and $d$ flavour Sivers
distribution functions, at the scale $Q^2=2.4$ (GeV$/c)^2$,
obtained in our present analysis with the $u$ and $d$
flavour Sivers functions we had found from our previous fit
\cite{Anselmino:2005ea}, where $\pi^0$ and kaon productions were not
considered, the Kretzer fragmentation function set was used, and only valence
quark contributions were taken into account in the polarized proton. This plot
shows that the Sivers functions previously obtained are consistent, within
the statistical uncertainty bands, with the Sivers functions presently found.
\end{itemize}

\section{Estimates for forthcoming experiments \label{estimates} }

\begin{figure}[t]
\includegraphics[width=0.35\textwidth,bb= 10 140 540 660,angle=-90]
{compass_sivers_proton_pi0.ps} \hskip 2.85cm
\includegraphics[width=0.35\textwidth,bb= 10 140 540 660,angle=-90]
{compass_sivers_proton_k0.ps}
\caption{\label{fig:compass_proton}
Estimates for the single spin asymmetry $A_{UT}^{\sin(\phi_h-\phi_S)}$
for pion and kaon production off a hydrogen target, which will be measured by
the COMPASS Collaboration.}
\end{figure}
\begin{figure}[t]
\includegraphics[width=0.35\textwidth,bb= 10 140 540 660,angle=-90]
{jlab12_sivers_pi0.ps} \hskip 2.7cm
\includegraphics[width=0.35\textwidth,bb= 10 140 540 660,angle=-90]
{jlab12_sivers_k0.ps}
\caption{\label{fig:jlab12_sivers-hyd}
Estimates for the single spin asymmetry $A_{UT}^{\sin(\phi_h-\phi_S)}$
for pion and kaon production, which will be measured at JLab operating on
a polarized hydrogen target with a beam energy of $12$ GeV.}
\includegraphics[width=0.35\textwidth,bb= 10 140 540 660,angle=-90]
{jlab12_sivers_neutron_pi0.ps} \hskip 2.7cm
\includegraphics[width=0.35\textwidth,bb= 10 140 540 660,angle=-90]
{jlab12_sivers_neutron_k0.ps}
\caption{\label{fig:jlab12_sivers-neu}
Estimates for the single spin asymmetry $A_{UT}^{\sin(\phi_h-\phi_S)}$
for pion and kaon production, which will be measured at JLab operating on
a polarized He$^3$ (neutron) target, with a beam energy of $12$ GeV.}
\includegraphics[width=0.35\textwidth,bb= 10 140 540 660,angle=-90]
{jlab12_sivers_deuteron_pi0.ps} \hskip 2.7cm
\includegraphics[width=0.35\textwidth,bb= 10 140 540 660,angle=-90]
{jlab12_sivers_deuteron_k0.ps}
\caption{\label{fig:jlab12_sivers-deu}
Estimates for the single spin asymmetry $A_{UT}^{\sin(\phi_h-\phi_S)}$
for pion and kaon production at JLab off a polarized deuteron target, with a beam energy
of $12$ GeV.}
\end{figure}

Using the Sivers functions determined through our fit, we can give
estimates for other transverse single spin asymmetries
$A_{UT}^{\sin(\phi_h-\phi_S)}$ which will be measured in the near future.
Fig.~\ref{fig:compass_proton} shows the results we obtain for the COMPASS
experiment operating with a hydrogen target, adopting the same experimental
cuts which were used for the deuterium target (Eq.~(71) of
Ref.~\cite{Anselmino:2005nn}).

Forthcoming measurements at the energies of $6$ and $12$ GeV are going to be
performed at JLab, on transversely polarized proton, neutron and deuteron
targets. The obtained data will be important for several reasons; they will
cover a kinematical region corresponding to large values of $x$, a region
which is so far unexplored by other SIDIS measurements. In particular,
a combined analysis of HERMES, COMPASS and JLab SIDIS data will allow a much
better determination of the $\beta$ parameters, which control the large $x$
behaviour of the Sivers distribution functions. In addition, the combined
analysis of proton and neutron target events will help flavour disentangling
and a more precise determination of $u$ and $d$ quark contributions.

Our estimates for the JLab SSAs, for pion and kaon production off proton,
neutron and deuteron targets, at 12 GeV, are presented in
Figs.~\ref{fig:jlab12_sivers-hyd}--\ref{fig:jlab12_sivers-deu}. At this
energy relatively large $Q^2$ values are available and the TMD factorization,
valid for $P_T\simeq k_\perp \simeq \Lambda _{\rm QCD} \ll Q$, should hold.
The adopted experimental cuts for a proton or a deuteron target are, in terms
of the usual SIDIS variables, the following:
\begin{equation}
\begin{tabular}{lll}
$0.3 \le z_h \le 0.8\;\;\;$ ~~~~~~~~ & $0.05 \le P_T \le 1.5 \;{\rm GeV}/c$ \\
$0.05 \le x_{_{\!B}} \le 0.7$  ~~~~~~~~ & $0.25 \le y \le 0.85$ \\
$1 \le Q^2 \le 8 \;({\rm GeV}/c)^2 $ ~~~~~~~~ & $W^2 \ge 4\;{\rm GeV}^2$ \\
$1.5 \le E_h \le 3.5\;  {\rm GeV}\;,$  & ~~~~~~~~
\end{tabular}
\label{JLab-12}
\end{equation}
whereas for a neutron target they are:
\begin{equation}
\begin{tabular}{lll}
$0.3 \le z_h \le 0.7$ ~~~~~~~~ &
$0.05 \le x_{_{\!B}} \le 0.55$ \\
$0.34 \le y \le 0.9$ ~~~~~~~~ &
$Q^2 \ge 1 \;({\rm GeV}/c)^2$ \\
$W^2 \ge 2.3\; {\rm GeV}^2 \;,$  ~~~~~~~~ & ~
\end{tabular}
\label{JLab-neutron-12}
\end{equation}
where, at order $(k_\perp/Q)$, one has $x_{_{\!B}} = x$ and $z_h = z$; the exact
relationships can be found in Ref.~\cite{Anselmino:2005nn}.

Notice that these estimates, while well constrained by the available SIDIS
data at small $x$ values, might be less stringent at large $x$ values:
for example, relaxing the assumption of a unique $\beta$ value for all
flavours, would only marginally affect our present fit of HERMES and COMPASS
data, but would much widen the uncertainty band above $x \simeq 0.4$.

We have given complete sets of estimates for charged and neutral pions and
kaons. While the $\pi^\pm, \, \pi^0$ and $K^\pm$ computations originate from a
consistent procedure which uses fragmentation functions and Sivers distributions
obtained by fitting data involving the same particles, the $K^0_S$ estimates
might be affected by a greater uncertainty about its fragmentation functions,
which require the assumptions of Eq.~(\ref{D0SFF}). This can be seen in the
comparison between data and computations of Fig.~\ref{fig:compass}.

We have also computed estimates for JLab operating at 6 GeV, with the
corresponding kinematical cuts:
\begin{equation}
\begin{tabular}{lll}
$0.4 \le z_h \le 0.7$ ~~~~~~~~ & $0.02 \le P_T \le 1 \;{\rm GeV}/c$\\
$0.1 \le x_{_{\!B}} \le 0.6$ ~~~~~~~~ & $0.4 \le y \le 0.85$ \\
$Q^2 \ge 1 \;({\rm GeV}/c)^2$ ~~~~~~~~ & $ W^2 \ge 4\; {\rm GeV}^2$ \\
$1 \le E_h \le 4\; {\rm GeV} \;,$ ~~~~~~~~ & ~~~~~~~~\end{tabular}
\label{JLab-6}
\end{equation}
for a proton or a deuteron target, and
\begin{equation}
\begin{tabular}{lll}
$0.46 \le z_h \le 0.59$ ~~~~~~~~ &
$0.13 \le x_{_{\!B}} \le 0.40$ \\
$0.68 \le y \le 0.86$ ~~~~~~~~ &
$1.3 \le Q^2 \le 3.1 \; ({\rm GeV}/c)^2 $ \\
$5.4 \le W^2 \le 9.3 \;  {\rm GeV}^2 $ ~~~~~~~~ &
$2.385 \le E_h \le 2.404\;  {\rm GeV} \;,$
\end{tabular}
\label{JLab-neutron-6}
\end{equation}
for a neutron target. The SSAs result to be almost identical to those obtained
at 12 GeV; therefore, we do not show them explicitely.

A word of caution is necessary when discussing JLab SIDIS observables at
6 GeV; in the high-$x$, relatively low-$Q^2$ JLab kinematical regime,
target and identified hadron mass effects (in particular for kaons),
large $x$ resummations and higher-twist effects might be significant.
This implies potential theoretical problems in the analysis of such data.
Notice, moreover, that a much better statistics should be expected at 12 GeV.

\section{Conclusions}

We have performed a comprehensive analysis of SIDIS data on Sivers azimuthal
dependences, taking advantage of new and more precise experimental results.
Particularly challenging are the HERMES data on kaon asymmetries, showing an
unexpectedly large value of $A_{UT}^{\sin(\phi_h-\phi_S)}$ for $K^+$.
Our results confirm and improve previous extractions of the $u$ and $d$ Sivers
distributions and offer first insights into the sea contribution to
the Sivers effect.

It turns out that the data demand a non vanishing, and large, Sivers
distribution for $\bar s$ quarks, which, coupled to a new set of fragmentation
functions enhancing the role of strange quarks, appears to be the only way, at
present, to explain the $K^+$ data. The other sea quark ($\bar u, \bar d, s$)
contributions are, at this stage, less well determined, although they also
seem to be non vanishing.

Taken at face value, the extracted Sivers distributions indicate a saturation
of the Burkardt sum rule mainly due to $u$ and $d$ quarks alone, which carry
almost opposite transverse momentum. The sea quark contribution is altogether
rather small. This seems to rule out a contribution from gluons and, somehow,
points towards a picture of the proton structure with the parton orbital motion
restricted to valence quarks.

Finally, we have used our extracted Sivers distributions to compute estimates
for ongoing and planned new experiments at COMPASS and JLab.

\acknowledgements
We are grateful to Carlo Giunti for stimulating discussions on the statistical
analysis of our results.
We acknowledge support of the European Community - Research Infrastructure
Activity under the FP6 ``Structuring the European Research Area''
program (HadronPhysics, contract number RII3-CT-2004-506078).
M.A.,~M.B., and A.P.~acknowledge partial support by MIUR under Cofinanziamento
PRIN 2006.
This work is partially supported by the Helmholtz Association through
funds provided to the virtual institute ``Spin and strong QCD''(VH-VI-231).

redpajama_set_name: RedPajamaArXiv


text:
Q: onActivityResult not called if Activity went into PictureInPicture mode Activities

*

*Activity A: content list

*Activity B: player

Flow
Activity A ==> Activity B

*

*Activity A launches Activity B using startActivityForResult

*Activity B might go into Picture-in-Picture mode

*Activity B calls setResult and then finish

*onActivityResult from Activity A is called

Issue
When Activity B goes into Picture-in-Picture, onActivityResult isn't called.
I know that Activity B detaches from Activity A's task stack when it goes into Picture-in-Picture, but I would expect the startActivityForResult to behave as expected. Is this a bug or is it expected ?
Any workaround would be appreciated. Also, my last resort is to re-do it all and use internal broadcasting to communicate both Activities. Feel free to comment on that as well.
Thanks!

A: I am not sure as I understand Activity in PIP mode is considered Pause.
But there is some development in the multi-resume feature.
To opt-in to this behavior in Android P, add the following meta-data in your app manifest:
<meta-data android:name="android.allow_multiple_resumed_activities" android:value="true" />

You can read about this here.

redpajama_set_name: RedPajamaStackExchange


LCD Competence. High Quality. Fair Pricing.
d.scaleHDII is a cost-effectively Scaler Board solution based on Realtek`s RTD2486 scaler family.
Plug & Play monitors for easy installation. TFT Displays with control in a housing. Various interfaces, touchscreen, surfaces and mounting options on request.
Complete industrial and digital signage display solutions such as display-kits or total solution touch displays with touchscreen directly integrated in the manufacturing process.
TFT display components for B2B customers from various manufacturers like AUO, Innolux, Evervision, Riverdi and PowerView. Special and semi-custom LCD panels on request.
LCD Panel Accessories and Accessories from Display Solution. Cable assembly according to cable plan and in-house developed and produced flexBridge adaptor boards such as HDMI to MIPI-DSI.
USB chips and ICs. Displaylink European Design Center and Distributor. USB high speed hub controller ICs and USB-over-Ethernet chips for USB device integration into networks.
Industrial TFT Displays, LCD Solutions and in-house developed Controller Boards. Contact our Visualization Professionals.


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Some clouds and possibly an isolated thunderstorm late. Low 74F. Winds S at 5 to 10 mph. Chance of rain 30%..
Some clouds and possibly an isolated thunderstorm late. Low 74F. Winds S at 5 to 10 mph. Chance of rain 30%.
UI, Carle to invest in rare, top-of-the-line MRI equipment
The hospital and the university are sharing the cost of the scanner as well as the installation and maintenance costs over the next 10 years. The UI's share will be $7.76 million, administrators told trustees Monday at a committee meeting.
UI, OSF research partnership on medical innovations getting $50 million boost
The new commitments for Jump ARCHES — Applied Research for Community Health through Engineering and Simulation — which was established in 2013 with $25 million from the financial technology firm Jump Trading, bring its total endowment to $112.5 million.
UI plans to lease 86,500 square feet in new building going up on Daniel Street
The space will be used for the growing School of Information Sciences, now headquartered in a former fraternity house a block away at 501 E. Daniel St., C, and for the new vice chancellor for diversity, equity and inclusion and his staff.
URBANA — New sexual-harassment complaints, including one made by the University of Illinois itself, have surfaced against UI Police Officer Br…
Move to UI 'no-brainer' for new dean of School of Information Sciences
Professor Eunice Santos, chairwoman of the computer science department at Chicago's Illinois Institute of Technology, was announced Friday.
IDOT claims proposal to widen Prospect would target only major intersections
The agency released more details on the plan Wednesday, saying the project was prompted both by safety concerns at intersections and overall pavement conditions.
Illinois Institute of Technology joins UI-led Discovery Partners Institute
Illinois Tech signed an agreement Wednesday to partner on the initiative, which is designed to bring students, faculty, industry and government together to spark discoveries, fuel economic growth and help retain the state's top talent.
State's plan to widen Prospect caught residents, Champaign officials by surprise
And the proposal for the section between Bloomington Road and Springfield Avenue has been met with concerns about traffic, speeders and encroachment on yards.
The millions donated by the lifelong Danville resident and Korean War veteran who made it his mission to help his hometown went to groups that advocated for children, education, the environment, health care, historic preservation, the arts, veterans and people with disabilities.
Kam's to be rebuilt at First and Green amid plans to reshape block it has called home
A building permit filed last week with the city of Champaign shows Kam's relocating to 102 E. Green St., C, the former site of a Domino's that's since been torn down, while the 600 block of East Daniel Street, where it stood for decades, is expected to be turned into a new apartment/retail/office complex.

redpajama_set_name: RedPajamaCommonCrawl


This mattress regularly gives hold your body where a body may need it by molding to its perfect shape. When you have a sleep on a twist mattress, at time of stress positions happen that interferes likely prepared of your shape. These pressure positions are finished when you relax in an air mattress. They can obstruct the normal twist in the spine if it is too hard, while it can basis unusual bends in the back by falling if it is too flexible.
Choosing the right category of an air mattress. If you need to be overstated physically have been roughly for every year. They are not only the common but also very expensive type available. At time, people had to use their lungs to raise a whole air mattress. Nowadays, the inflation plan has become much simple because any of the access on the market now has a closed electric pump.
Self-inflatable air mattresses created of perforate opposed to materials with one cell bubble sandwiched in among. These mattresses are heavier since the extra layering, but it also gives enough insulation. These mattresses have an intake regulator that can open, permitting it to inflate on its own, and can be used to change the air to your taste.
Air mattress is in different sizes that are available examples are queen, twin, and double size. There are also size that is called king size which accessible but carry quite of bit of room in your tent. Make sure that the mattress you choose will fit well in your tent, If only you will use it outside, example camping . Before selecting an air mattress, also consider how many people will sleep on it to reduce congestion .


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File under: Everything, Features November 20, 2014
PREVIEW: Dragon Age: Inquisition [PC/PS4/XOne]
Jonny Robot
Dragon Age, and I say this at the risk of being skewered by a 'Precise Shot' arrow, has always struck me as the Billy Baldwin in the Bioware family. Sure, he may not be as charismatic, charming and innovative as Alec (who's totally Mass Effect, if you're indulging me with this analogy) and, sure, he may have stumbled pretty hardcore whilst trying to reinvent himself mid-career but the fact remains that he still has star potential, damn it! Star potential!
Having scored some hands on time with the new look Billy Baldw- I mean, Dragon Age: Inquisition at PAX AUS earlier this month, it truly seems like third time is the charm for this franchise of high adventure!
DA: I (as the cool kids on the internet will undoubtedly call it) starts off with your protagonist waking up after what I can only describe as a medieval acid nightmare, only to find themselves restrained by shackles and accused of murdering the high lords of the realm. After some obligatory exposition, it turns out you are "the one" and only you can stop the onslaught of darkness- blah, blah, insert usual fantasy tropes here. Hold on though, because here's where we're going to take a Colin McRae extreme hard left- who the fuck cares? After playing this game for about three hours, the main story was already so far off my radar that it didn't matter. What I took away from my time with DA: I was that this was MY story, which I could play MY way and that was pretty darn cool.
DA: I wastes no time becoming personal, laying it on thick as soon as you boot that sucker up and start creating your Jesus allegory. I have one word to describe character customisation in this game: Mind-blowing! (Hyphenating makes it count as one word). Every possible aesthetic option has been boosted to overwhelming levels of manipulation, allowing you to edit from the minutest to major of details. There's the usual options like hairstyles, scars and nose bridge angle (with about 20 alteration sliders each) but then it goes and rolls up its sleeves, allowing you to edit things like the inner and outer iris colours AND then even bends the in-between to work! Who does that!? DA: I does!
That freedom of character customisation isn't limited only to aesthetics, flowing over into your character's build type as well. No 'class' is closed off to you from picking certain race or gender (so you can finally be that Dwarven mage you've always dreamed of) and even classes lack a certain rigidity, allowing you to mix and match abilities from multiple skill trees. I went ahead and rebuilt my heroine from DA: Origins, the Valkyrie-esque Templar Cassandra, albeit more bad-arse and scarred up, since I had that option now!
Cassandra always favoured the sword and shield approach, which I picked again, with all that really just dictating my starting abilities. Soon I had a charging rush from the two-handed tank tree, a precision strike from the rogue tree and shield buffs from my starting class. I (well, Cassandra) was the Frankenstein's monster of combat and it was liberating!
Half of that liberation, without a doubt, came from the new overhauled combat system. If I was Franky's monster, combat was easily my bride. The system behaves like a strange amalgamation between the tabletop RPG system of DA: Origins and the watered-down, fluid combat from DA: 2 but with a way higher air of accessibility on both sides. Movement is keyed to WASD, general weapon swinging is mapped to the left click and your abilities sit waiting to be unleashed in a hotbar. Sure, it's nothing revolutionary but it doesn't need to be, it just needs to work well and feel intuitive, which it totally does. The other major key you'll be hitting a lot, and I mean a lot, is the space bar, which allows you to freeze time.
This is an old school mechanic, dating back to games like KOTOR, which allows you to better judge the battlefield and tactfully command your party. This is essential to victory, without it you might as well fall on your own sword! Each party member has a role to play, with their own specific weaknesses and strengths. Knowing when and how to use them will make or break even the smallest of skirmishes and leave you feeling like you have the combat knowledge and power of command to bitch slap even Sun Tzu!
[img_big]center,11405,2014-04-23/daprintfeb_3.jpg,Dragon Age: Inquisition[/img_big]
In between your glorious campaigns of cutting down Darkspawn, DA: I asks you to explore its sprawling world and this is not something to be taken lightly. The world is huge and full of things to discover. Employing that Skyrim mentality of picking a point on the horizon and sauntering off towards it, not knowing what you'll discover, is the apex of adventure and it's implemented wonderfully here. It's during these random jaunts that you truly notice how gorgeous DA: I is, with Bioware milking the Frostbite engine for all its worth.
During combat, the fireworks and ensuing particle effects of spells and abilities are alluringly captivating, but its true beauty manifests in moments of downtime. Each new area comes with its own distinct feel, asking you to explore every glade, thicket and pile of rocks. Whilst plodding through a forest (which is par for the course in fantasy RPGs), I had to stop and take in what was around me. The trees were swaying in the wind, leaves gingerly spiralling towards the ground where mist lay, slowly rolling. The sunlight gleamed up ahead, radiating my path towards an open vista, which sat adjacent to a grand, foreboding mountain. It was pure serenity. The world was mine to discover as quickly or (more likely) as snail paced as I wished, and no amount of NPC nagging to hurry up could alter that- well, except for the lake looking like a great place for them to have an 'accident'.
Dragon Age: Inquisition is the kind of game I can see eating into many hours… weeks, hell, months of my life when it hits PC (and both next gen consoles) on the 20th of this month. The captivatingly gorgeous world, charm-ridden writing, overhauled combat and focus on YOUR adventure makes it stand out, beating its chest, from many other fantasy RPG's from the past or present. If you've even got a little love in you for fantasy, adventure, or guys with tipped ears, this could easily be your game of the year!
Tags: Alec Baldwin, Billy Baldwin, BioWare, Dragon Age, Dragon Age 3: Inquisition, Dragon Age II, Dragon Age: Inquisition, Dragon Age: Origins, Electronic Arts, Mass Effect, PAX Australia 2014, Star Wars: Knights of the Old Republic, The Elder Scrolls V: Skyrim


If there is one thing I've learned since the start of designing my website it is how much work it takes to create an online space. Many days and nights have been spent trying to form a site that felt just right. With all that being said, many people helped along the way, volunteering their time and energy into developing Style Rituals and I want to take a minute to thank a few who I couldn't have done all this without.
Katherine Killeffer, thank you so much for all of the beautiful artwork that you have conceived for this site. You took what was just an idea forming in my head and truly made it come to life. Thank you for all of your patience during our concept meetings and thank you for just getting me.
Eva Gajzer, you are my ultimate branding guru and your advice throughout this process has been nothing short of amazing. Thank you for all the time you have spent helping to evolve and grow my brand concept.
Christina Carathanassis, thank you for helping me expand what was just a thought into an entire business. Your ability to take a concept and give it such spirit through your writing has not gone unnoticed. Thank you for giving my site the perfect amount of CC enthusiasm.
To everyone else who has helped along the way. Thank you, thank you, thank you!
As impressed with my friends as I am? Click on their names to find links to their own sites.


10/01/2017�� Tuna salad is perfect for lunch, sandwiches, a light snack, or a picnic. Everyone has a favorite tuna salad recipe, and now with our easy tuna salad recipe �... This salad employs avocado and yogurt to give you the creaminess you desire in your tuna salad and it does not disappoint. I have used two cans of albacore tuna, packed in water. I have drained and flaked the tuna.
This plant-based chickpea salad is reminiscent of a classic chicken or egg salad with a healthy twist! Perfect for lunches or a snack, this recipe is a snap to make and so refreshing! Perfect for lunches or a snack, this recipe is a snap to make and so refreshing!
Tuna quinoa salad packed with protein, fresh spring veggies and a green goddess avocado dressing. Delicious and so easy to make! My Dad used to make the BEST tuna pasta salad on the planet.


Rental lodges offer a great place to stay outside of the typical hotel.
Rentals such as condos and cabins are an excellent option for those who wish to feel right at home, even while away on vacation. Fully equipped kitchens, multiple bedrooms, and laundry amenities make staying in rental properties an attractive option for many tourists. Rentals are also ideal for those who are traveling in a bigger group, perhaps vacationing with friends or visiting for a family reunion. Renting one large condominium or cabin is often times less expensive than renting multiple hotel rooms, and often is a better fit for such groups.
The Blacks Hills area of South Dakota is an ideal location for cabins due to the picturesque scenery and the seclusion that the forests offer. Visitors to South Dakota will love the rustic feel cabins and condominiums provide, and will enjoy a completely different experience than those who simply choose to stay in a hotel room.


Here are 10 chord melody arrangements for classic standard songs. For each of the 10 standards, you get a performance video and a detailed breakdown of each of the arrangements. I break it down note for note going over each chord in the arrangement. Also included is a pdf of the manuscript with TAB. 10 Songs include: After You've Gone, I'll See You In My Dreams, It Had To Be You, Somebody Loves Me, All By Myself, You Made Me Love You, Nuages, Always, I'm Confessin', and Whispering.
Indie Courses are video course downloads produced independently from TrueFire. Recorded in Frank's studio, these products present fresh educational concepts and effective teaching methodologies. Indie Courses are exclusively available for purchase in Frank's channel store and can be downloaded via the TrueFire apps for Windows, Mac, iOS, or Android. Indie Courses are NOT available for streaming on the web — they are in-app only items.


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Pendleton council gets first budget look; braces for business tax changes
Mike Eads
michael.eads@independentmail.com
Pendleton town budget expected to be around $4 million again for FY 2017
State House bills could affect $260,000 in local business fees town collects now
Construction activity starting at the Grove of Pendleton development
Pendleton is growing, but town officials said Saturday they're able to keep up with that growth so far.
The Pendleton Town Council met with Administrator Steve Miller and department heads Saturday morning at Town Hall for breakfast and a first look at next year's budget.
Projected expenses and revenues look similar to recent years, according to Miller. The current fiscal year budget is roughly $4.2 million, including $2.7 million held in the general fund and the addition of around $250,000 per year for the town's recently restarted police department.
Miller said the town's tax revenues are keeping up with inflation, but that could change if some state legislators get their way. House members are looking at two measures to standardize how municipalities assess and collect business taxes, despite loud protests from cities and towns that it will cost them money when the Legislature already fails to meet funding obligations to them.
"They're good at coming up with ideas … but they don't give you a way to replace that revenue," Mayor Frank Crenshaw told the council members. "It's like unfunded mandates or the local government fund."
Councilwoman Sandra Gantt agreed with Crenshaw. She noted one of the House proposals would create a new system that would tax locally owned businesses harder than regional and national retailers, and cut into tax collections.
"What they're saying is they don't want you to tax those (national) folks," Gantt said.
Miller said the various business fees and taxes Pendleton assesses now account for around $260,000 per year, or about 20 percent of the annual budget.
Business tax changes notwithstanding, Miller said the town's annexation of the 350-acre Grove at Pendleton site at U.S. 76 and S.C. 187 would improve the town's tax collections. The new Waffle House restaurant is expected to open soon just north of that intersection and pay taxes similar to the $30,000 or so assessed annually to the nearby Bojangles restaurant. He added that a housing contractor is talking to the town and developer Richard Bennett about starting residential construction on the Grove site.
The town has agreed to spend up to $2 million on sewers and a lift station to serve the $50 million-plus in businesses and homes expected to pop up there over the next several years. The extended service could also add the Pendleton High School campus and more customers further south along S.C. 187 onto the town's sewer utility, bringing in revenue that could offset future rate increases for existing customers.
Much of the rest of the $6.7 million in capital projects the town has in the works will be covered with different forms of state and federal money, including state loan forgiveness for $1.1 million in sewer line replacement work on the south end of town and most of the $750,000 cost for the Mechanic Street beautification project along the Village Green.
Follow Mike Eads on Twitter @MikeEads_AIM


"Just a quick note to sat thank you so much for a fantastic weekend, you really do have an amazing spot down there!"
Is a cosy cottage facing South over the courtyard.
This cottage sleeps up to six. It has an attractive living room with a vaulted roof, exposed trusses and a beautiful open corner fireplace.
We also have a Laundry room with washing machines, tumble dryer, and ironing facilities, there is also a public telephone.


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Q: How to add button on SharePoint allitems.aspx list view column and update list items on its click event? I want to achieve following functionality
1) Create button on SharePoint document library column on allitems.aspx view.
2) On clicking of that button document library field values should get updated.
I could create button on allitems.aspx listview using designer in SharePoint 2010, but could not do it in SharePoint 2013 as there is no design view in SP2013 designer.
Which is the best way to update doc library items on column button click? Please share the detailed steps if possible.


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Topics › Education
Analysis of Texas School District Open Enrollment Data
Three percent of Texas students transferred to a traditional public school outside of their assigned school district in the 2018-2019 school year.
Jordan Campbell
Aaron Garth Smith
Open enrollment policies provide educational opportunities for families by allowing students to enroll in a public school outside of their residentially assigned school district. The needs of every student are different and providing more educational options ensures that students can be successful. Yet, little is known about open enrollment in most states despite the fact that research shows it provides positive benefits for families.
In cooperation with the Texas Public Policy Foundation, Reason Foundation has created the Texas Student Transfer Dashboard to shine a light on open enrollment trends in the state. The interactive tool below maps the 2018-2019 student transfer data for every public school district in Texas. It also provides charts that show these trends by school district ratings and school district student demographics.
There are two types of open enrollment: Intradistrict refers to transfers within a child's home school district, while interdistrict refers to transfers outside of a child's home district. The subject of this research is exclusively on interdistrict open enrollment.
Our analysis finds that three percent of Texas students transferred to a traditional public school outside of their assigned school district in the 2018-2019 school year.
Importantly, these students tended to transfer to higher-performing school districts as measured by state accountability grades. In 2018-2019, roughly 45,000 Texas students transferred to a higher-performing school district at least a letter grade above their residentially assigned district.
We also find that students tend to leave lower-income school districts at greater rates than higher-income school districts, although it's not possible to determine the demographics of these students due to lack of state and school district reporting policies.
Additionally, we observed that Texas school districts accept transfer students at varying rates, with some school districts enrolling thousands of students from outside of their boundaries and others enrolling none at all. Because the state does not report school district transfer policies it is difficult to know how widespread transfer opportunities are and whether additional seats are available for students.
It is clear though that there are substantial policy barriers to ensuring that all of Texas' students have access to robust open enrollment opportunities. These include inadequate protections for families, opaque transfer processes, as well as limited support for transportation outside of a student's residentially-assigned school district.
There is also a real need for increased transparency and reporting on open enrollment at the state level. While Texas' open enrollment data is vastly better than most states, it still falls well short of providing stakeholders with the information they need to make sound policy decisions. Because of this, it is impossible to determine the demographics of transfer students, their reasons for transferring, or even the schools they are leaving from and going to. Steps should be taken to ensure these and other data—including school districts' transfer policies—are collected and reported regularly.
The interactive tool below allows users to see which school districts in Texas have the highest rates of student transfers. The tool also shows how student demographics and district performance impact transfer trends. The full dashboard is also available here.
More from Education
Public education needs the private sector
A significant portion of the $751.7 billion spent annually on K–12 education is used to purchase non-public goods and services.
By Aaron Garth Smith
Best practices for K-12 special education funding
There is no one right way to fund special education because each student and school district is unique. However, several principles can be a useful guide for lawmakers looking to improve how they fund special education students.
By Christian Barnard
Best practices for funding low-income K-12 students
States vary substantially in how much additional funding they allocate to low-income students, how the funds are delivered, and how they identify low-income students.


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Hackney young people celebrated for anti-smoking films
cutfilms_allhackneywinners2015.jpg
Over 300 young people, teachers and youth workers from across Hackney celebrated the creativity and imagination of local young people at the Hackney Cut Films 2015 Awards at the Rio Cinema, Dalston.
The awards, held on Monday 29 June 2015, celebrates the filmmaking talent of over 1,100 young people, who have made short films to persuade their friends and family not to smoke. The awards celebrate the best films of the borough, with the top 15 winning films shown out of 134 submitted.
The competition, run by Cut Films and funded by Hackney Council, asks young people in Hackney schools and youth projects to research smoking and tobacco, make a two minute short film about the issues associated with youth smoking, and upload it to the competition website and share it on their social media for their friends to see.
The Overall Judges' Choice winner is Dempsey Miah (Hackney Community College), with his film 'Smoker'. The Overall Popular Choice winner is New Hackney School with their film 'You Are Your Own Monster'.
Young filmmaker Mickel Babatunde (aged 12) said: "Our film is about the effects that smoking can cause. We enjoyed Cut Films because we were able to express our creativity and I liked that it gave us an opportunity to have our voice heard."
Paula Brocki, Leader of the core department, Hackney New School said: "Cut Films have provided an excellent opportunity for our students to excel in an area that they wouldn't necessarily have had a chance to learn about, like film-making. It gives students a voice through film production and gives them a chance to have their voice heard on issues that affect them. A truly enriching experience for the students involved."
We're making great progress in reducing rates of smoking in Hackney, but far too many people still take up the habit, with many starting in their teens. It's so important to involve young people in educating their peers about the dangers of tobacco, which is why we've continued to support Cut Films. I'm delighted that so many young people have taken part this year and that the standard of film-making is so high. Congratulations to our local winners and all those who took part and supported the project this year, and best of luck to those who have been shortlisted for the national awards.
A professional filmmaker from Cut Films supported teachers and youth workers to create the films with young people, taking the film production process from script to screen.All films in the Hackney competition have also been entered into the National Cut Films competition and two have been shortlisted to be screened at BAFTA HQ on 1 July 2015.
The films the pupils have made are varied and cover a range of tobacco-related issues. The children worked in small filmmaking groups, with some exploring the issue of peer pressure and others tacking the health effects of smoking. There is a wide variety of styles represented in the students' films from comedy to spoken word.
Find more information at www.cutfilms.org/Hackney.
For more information about Hackney Cut Films contact:
Emma Wrafter
Charity Director Cut Films
emma@cutfilms.org / T: 020 7700 3701 / M: 078179 42689
About The Deborah Hutton Campaign and Cut Films
The Deborah Hutton Campaign is a peer-to-peer smoking prevention charity. Our short film and social media project, Cut Films, educates young people about smoking in a creative way. The Campaign works in partnership with Government, local authorities, schools and youth groups to deliver targeted smoking interventions.
The Deborah Hutton Campaign was set up in memory of Deborah Hutton who was health editor at Vogue for over 20 years. In 2004 Deborah was diagnosed with Stage IV advanced lung cancer. She died eight months later aged just 49. Deborah smoked when she a teenager, tried her first cigarette when she was 12, smoked regularly from 17 and gave up aged 24. Cut Films is her legacy.


Mayor de Blasio has 'fessed up to an unfortunate truth: He doesn't know what his top minions are doing. Rather, he says, he sets out "broad goals" for his deputies, who then run with them.
Problem is, this mayor isn't hands-off — he's checked-out.
The statement is a bid to avoid being deposed in a lawsuit that argues city affordable-housing policy is racist. No matter that affordable housing is a signature de Blasio issue: His "I know nothing" defense rings all too true.
Time and again, he has denied major problems at one agency or another, admitting the truth only when he has no choice left.
Candidate for governor Mark Molinaro discusses the corrosive culture of corruption in Governor Cuomo's Albany and how New Yorkers deserve a government as great as they are.


With that out of the way, something has to be done about the ridiculous overtime rule in the NFL. We saw it firsthand this past weekend when the Chiefs and New England went into OT in their AFC Championship Game. By winning the coin toss, the Patriots got the ball first and drove down for a TD, thus ending the game. The Chiefs did not get a chance to even touch the ball on offense.
Think about it: In what other sport does a team that wins a coin toss get to have possession and then can win a game without their opponents even having a chance? Baseball? Nope. If the game goes into extra innings, both teams get to bat. Think of the outrage if MLB changed the rule and the first team that scored in extra innings would win (that would have to be the road team in this case). Stupid, right? You bet. At least in baseball each team gets an at-bat in extra innings. If the road team scores a run in the top of the 10th, the home team must either score one or two runs or the game is over.
As it states right now, the team that wins the coin toss in an NFL overtime game wins if they score a TD. If that team has to punt or commits a turnover, or if they kick a field goal, the other team has a chance to have possession. I say that even if that team that wins the toss scores a TD, let the other team have a possession. If they don't score a TD, then the game is over. If they do score a TD, then, and only then, do you make the game sudden death. At least each team had one possession. If you want to reward the team for winning the coin toss, at least let the other team get one possession. What happens after that is fair game.
NFL… The ball is in your court. Or should I say, you have possession. Let's end this discussion about how unfair the overtime format is once and for all.
Totally, totally agree. Teams work too hard all year to lose a shot at the Super Bowl due to a coin toss result.


Charlize Diamond Heart Pendant featuring 9 Round cut diamonds, total diamond weight of 0.095 ctw carat. Create your pendant with Material options of 14K, 18K Gold and 950 Platinum; Color options of White, Yellow, Rose Gold and White Platinum; Gem options of Ruby, Blue Sapphire, Pink Sapphire, Emerald, Diamond. Made in New York, USA.


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Home Food Kids
Child calls 911 to document being left in warm vehicle with 6 other children
A Maryland mom's shopping ride resulted in her being hauled off to prison after a young child called 911 to mention that he and six other children had been left in a warm vehicle via themselves, authorities said. Charles County deputies received the call simply after 1 p.M. On Friday. The child advised a 911 dispatcher he did now not realize in which they were; however, the government was capable of tracing the decision to a mall parking zone in St. Charles, Maryland, the Charles County Sheriff's Office said in a press release.
A long time 2 to 4, the seven youngsters had been located within the car, which had its home windows rolled up. Authorities stated the kids had been left unattended for at least 20 minutes. Officers helped the youngsters out of the car, and Charles County Fire/EMS furnished treatment at the scene," the sheriff's office stated. According to WJLA, the youngsters have been "scared" and "sweaty." Temperatures within the place climbed up to around 80 stages on Friday. Authorities consider the four-yr-old used a cellphone left inside the car to name for help.
Line with the outlet. It is against the law to leave a baby below the age of 8 unattended inner a motor car if the caregiver is out of sight of the child except for a reliable character at the least 13-years-antique stays with the child," the sheriff's workplace stated. It is likewise dangerous to leave anyone, consisting of pets, inside a motor car, mainly as outdoor temperatures become hotter. A parked vehicle's temperature can fast rise to extremely high and even deadly ranges in a short time frame. A 37-yr-old girl arrived lower back at the automobile approximately 10 minutes after police. The woman, who's the mother-of-the kids and changed into babysitting the others, was arrested and charged with the confinement of kids inside a motor car.
Fast food presented to school students as group of workers, funding shortages pressure canteen closures


POTD. Prompt was more than 6. I put together a new kit with 9 boxes of Lego.
I finished up purging November 2011. I started collecting POTD for December. I missed a whole week of posting because I was getting ready for family to visit. I managed to find photos that I had taken for those days. I began the layout and realized we had to get ready for the movie. I got all the photos placed on the first page before I had to quit and fix lunch.
Andy & I went to see Cars 2. I cannot believe how expensive movie tickets are. It is much cheaper waiting for the DVD. For the two of us it was $15.50. Thankfully we don't get snacks.
The movie was more enjoyable than I expected. I am not sure little kids would get all the references to James Bond. Finn McMissile can do anything. Andy got bored about half way through. He wanted to move higher up which we did. Then he wanted to listen to his iPod. Ironically he chose to watch Curious George which is the first movie I took the boys to. We left about 2/3 in.
I wanted to stay past the credits but Andy was ready to leave so we did. We stopped at McDonalds for fries.
December 2008 POTD. Now that the POTD layouts for 2008 are done, I am wondering if I should have a photo book made or start another alba just for POTD. It would be cheaper to do the album.
Purged more photos. Realized I have not done anything with the photos when my family came to town. There are some funny shots between Nancy and John.
I am hungry. I fixed myself a smoothie. By avoiding sugar, my cravings are down and I have calories left over.


Good news for all the boozers out there: Yet another company in Philly is offering beer delivery.
Old City's Bistro 7 is a bistro no more! Say hello to Dos Rosa Taqueria.
LISTED: Here are my top 3 picks to appear on the market yesterday.
Claustrophobes must love units in Locust Point like this one, with their high ceiling and massive windows.
For those who like more cozy spaces to explore, this charming historic rehab in Northern Liberties might be the answer.
If your jam is a South Philly row that looks like anything but inside, this industrial loft-esque home might be for you.
We're getting not one, but two new TJ MAXX stores in Philly. Shop til you drop!
With the news that the Schuylkill Swing Bridge is gearing up for a long awaiting trail connection, We're trailblazing towards new trails!
PlanPhilly's Jim Saksa takes another thoughtful look at the state of, and cause for gentrification.