You will be presented with the full text of a science research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
gravitational effects of dark matter have been observed in galaxies , clusters of galaxies , the large scale structure of the universe and the cosmic microwave background radiation .
these observations indicate that dark matter accounts for about @xmath0 of the matter density in the universe and for @xmath1 of its total energy density . it must therefore be considered today to be one of the essential ingredients of our universe .
viable dark matter particles should be neutral , stable and weakly interacting , and , to be consistent with the observed large scale structure of the universe , behave as _ cold _ dark matter . since none of the standard model particles satisfies these conditions , dark matter provides strong evidence for new physics , and
indeed most extensions of the standard model include dark matter candidates .
wimp ( weakly interacting massive particle ) dark matter represents a generic scenario , that can naturally account for the observed dark matter density via freeze - out in the early universe . here
, the dark matter candidate is a weakly interacting particle with a mass around the tev scale - the same scale that is currently being probed by the large hadron collider ( lhc ) at cern .
the idea behind minimal models of dark matter is to extend the standard model in a minimal way , so that dark matter can be explained .
typically , these models feature a small number of additional fields and a new discrete symmetry that stabilises the dark matter particle .
they include models such as the inert doublet model @xcite , the radiative seesaw model @xcite , and the singlet fermion model @xcite .
the coexistence of two dark matter particles is yet another possibility that is currently being explored @xcite , as are coannihilations of dark matter and other particles @xcite .      in this model ,
the standard model is extended with an additional scalar doublet , @xmath2 , which is assumed to be odd under a discrete @xmath3 symmetry .
the dark matter candidate is the neutral component of this new doublet ( @xmath4 ) and is then a wimp featuring gauge and scalar interactions .    at the tree level ( see fig .
[ fig:1 ] ) , the @xmath5-@xmath4 scattering relevant for direct detection    tree - level feynman diagram for the direct detection cross section of inert higgs dark matter . ]
proceeds via a higgs - mediated diagram and is determined by a scalar coupling .
following the recent lhc discovery of a standard - model like higgs boson , we set @xmath6 gev .    at the one - loop level ( see fig .
[ fig:2 ] ) , the spin - independent direct detection cross section receives new contributions from @xmath7- and @xmath8-mediated diagrams which are determined by the gauge couplings .    as a result
, the one - loop contribution can actually dominate the direct detection cross section .
in fact , it provides a lower bound on the spin - independent cross section that is within the reach of planned experiments such as xenon1 t @xcite ( see fig .
[ fig:3 ] ) @xcite .
scatter plot of the spin - independent direct detection cross section at tree - level and at one - loop as a function of the dark matter mass . in this figure
all the parameters of the inert higgs model were allowed to vary randomly and all experimental bounds were taken into account @xcite . ]
the radiative seesaw model is an extension of the inert doublet model by three singlet fermions @xmath9 that are odd under the @xmath3 .
its lagrangian includes the following terms : @xmath10 the main feature of this model is that it can account also for neutrino masses .
they are generated at one loop and are given by @xmath11    if some of the singlet fermions have a mass slightly larger than that of @xmath4 , coannihilations with @xmath9 become relevant and give rise to an _ increase _ in the relic density ( see fig .
[ fig:4 ] ) .    the relic density as a function of @xmath12 for different values of @xmath13 . in this figure
we have set @xmath14 , @xmath15 , @xmath16 and we have assumed that the three fermions have the same mass : @xmath17 . notice that @xmath18 decreases with increasing @xmath13 @xcite . ]
the relic density thus strongly depends on the mass difference between @xmath4 and the singlet fermions .
the resulting indirect detection rate is large and provides a constraint on the parameter space of the model ( see fig .
[ fig:5 ] ) @xcite .
regions in the plane ( @xmath12,@xmath19 ) that are consistent with the dark matter constraint for different numbers of coannihilating @xmath20 @xcite . ]
the region in the plane ( @xmath21,@xmath12 ) that is compatible with the dark matter constraint .
different symbols are used to distinguish the dominant annihilation final states .
the dashed ( red ) line shows the resonance condition : @xmath22 @xcite . ]      in this model , the standard model is extended with a singlet fermion ( @xmath23 ) and a singlet scalar ( @xmath24 ) , which are odd and even under a @xmath3 , respectively .
the fermion is therefore the dark matter candidate and interacts via @xmath25 the new scalar mixes with the higgs boson , giving rise to the mass eigenstates @xmath26 and @xmath2 .
the dark matter annihilates mainly into four different channels : @xmath27 , @xmath28 , @xmath29 and @xmath30 ( see fig .
[ fig:6 ] ) . as one can see in fig .
[ fig:7 ] , some regions of the parameter space can already be excluded by direct detection constraints .
the reach of current and future direct detection experiments @xcite in the singlet fermion model below the resonance @xcite . ]
using three different examples for minimal extensions of the standard model , we have illustrated in these proceedings the interplay of the higgs boson discovery and dark matter relic density constraints and their implications for direct and indirect searches for dark matter .
i thank s. esch , d. restrepo , j. ruiz - alvarez , c. yaguna and o. zapata for their collaboration .
financial support by the helmholtz alliance for astroparticle physics and the deutsche forschungsgemeinschaft under grant kl 1266/5 - 1 is gratefully acknowledged .
m.  klasen and c.  e.  yaguna , jcap * 1311 * ( 2013 ) 039 [ arxiv:1309.2777 [ hep - ph ] ] and references therein
. m.  klasen , c.  e.  yaguna and j.  d.  ruiz - alvarez , phys .
d * 87 * ( 2013 ) 075025 [ arxiv:1302.1657 [ hep - ph ] ] and references therein .
m.  klasen , c.  e.  yaguna , j.  d.  ruiz - alvarez , d.  restrepo and o.  zapata , jcap * 1304 * ( 2013 ) 044 [ arxiv:1302.5298 [ hep - ph ] ] and references therein . s.  esch , m.  klasen and c.  e.  yaguna , phys .
d * 88 * ( 2013 ) 075017 [ arxiv:1308.0951 [ hep - ph ] ] and references therein .
s.  esch , m.  klasen and c.  e.  yaguna , arxiv:1406.0617 [ hep - ph ] and references therein .
b.  herrmann , m.  klasen , k.  kovarik , m.  meinecke and p.  steppeler , phys .
d * 89 * ( 2014 ) 114012 [ arxiv:1404.2931 [ hep - ph ] ] .
j.  harz , b.  herrmann , m.  klasen , k.  kovarik and q.  l.  boulch , phys .
d * 87 * ( 2013 ) 5 ,
054031 [ arxiv:1212.5241 ] . b.  herrmann , m.  klasen and q.  le boulch , phys .
d * 84 * ( 2011 ) 095007 [ arxiv:1106.6229 [ hep - ph ] ] .
e.  aprile [ xenon1 t collaboration ] , springer proc .
* 148 * ( 2013 ) 93 [ arxiv:1206.6288 [ astro-ph.im ] ] .
the existence of dark matter provides compelling evidence for physics beyond the standard model . 
 minimal extensions of the standard model with additional scalars or fermions allow to explain the observed dark matter relic density in an economic way . 
 we analyse several of these possibilities like the inert higgs and radiative seesaw models in the light of the recent higgs discovery and study prospects for the direct and indirect detection of dark matter in these models 
 .    dark matter , minimal models , higgs boson    ms - tp-14 - 28