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:
the photon collider option of a linear collider ( lc ) is based on laser photon back - scattering on high energy electrons .
the maximum photon energy is 205  gev for a laser with @xmath0 and an electron beam energy of 250  gev .
a high degree of polarisation with opposite helicities of the electron and the laser photon is crucial for obtaining a peaked spectrum of high energy polarised photons close to the maximum energy . in this case
the high energy part of the @xmath1 spectrum is dominated by the spin-0 configuration which is important to enhance the signal and suppress the background for higgs production
. alternatively , e@xmath2 interactions are also possible .
the technical aspects of the photon collider are discussed in  @xcite .
neutral higgs bosons are produced in the scattering of two photons as a @xmath3-channel resonance through a loop . in this loop
all charged particles contribute which obtain their mass from electroweak symmetry breaking .
the two - photon partial width of the higgs boson is therefore sensitive to physics beyond the sm .    for higgs bosons decaying predominantly into @xmath4 , the main source of background
are @xmath5 processes ( q = c , b ) .
the spin-0 component of these processes is suppressed in leading order ( lo ) by a factor @xmath6 . since
this suppression is only valid in lo , a realistic background simulation should be based on a next - to - leading ( nlo ) calculation .
several analyses of @xmath7 decays for a sm higgs boson in the mass range from 120 gev to 160 gev have been performed  @xcite .
all analyses exploit the kinematic differences between the @xmath3-channel signal and the @xmath8-channel background by cutting on visible energy and angular distributions .
the results are shown in fig .
[ fig - wcorr ] .
[ fig1 ]    before b - tagging the ratio of background from @xmath9 events to @xmath10 events is approximately 16 due to the quark charges .
excellent b - tagging is therefore required to suppress the charm background .
the need to minimize the radius of the beam pipe is one of the main challenges for a photon collider , since the beam pipe has to accomodate the optical system for producing back - scattered photons .
the analyses presented here have assumed that @xmath4 events are tagged with @xmath11 efficiency and @xmath12 events with @xmath13 efficiency . for a luminosity corresponding to roughly one year of running , a statistical uncertainty of about @xmath14 for a higgs mass of 120 - 140  gev for the two photon width measurement
can be achieved .
the uncertainty increases to about @xmath15 for a higgs mass of 160  gev .    at higgs boson masses above 160
gev decays into ww and zz pairs become important . in this case
the interference between signal and @xmath16 background needs to be taken into account .
the interference gives access to an additional observable , the phase @xmath17 of the @xmath18 amplitude .
the combined precision of phase and partial width determination gives sufficient precision to distinguish the sm from sm - like 2hdm ( ii ) scenarios  @xcite .
the results of a detector simulation are shown in fig .
[ fig - ww ] .
the neutral mssm higgs boson h , a for masses above 200  gev and for moderate @xmath19 might escape detection at the lhc . in this parameter region , where decays into @xmath4
are the dominant sm decays up to higgs masses around 550 gev , the photon collider can discover the neutral mssm higgs bosons  @xcite .
in contrast to the @xmath20 option of the lc , the photon collider can produce these higgs boson with masses up to about @xmath21 of @xmath22 .
cross - sections for signal and background are shown in fig .
[ fig - mm ] .
many other higgs scenarios have been studied for the photon collider option , adding to the discovery potential : for example , the measurement of cp properties of the higgs bosons a , h in @xmath23 decays  @xcite or the production of charged higgs bosons in the process @xmath24  @xcite .
one of many other interesting topics which can be studied at a @xmath1 or at an e@xmath2 collider are non - commutative quantum field theories ( ncqft ) with non - commuting ( nc ) space - time operators  @xcite .
the additional cubic coupling ( @xmath25 ) contributing to the process @xmath26 is shown in fig .
[ fig - qed ] .
the parameter @xmath27 characterises the threshold where nc effects become relevant .
the current limit from @xmath20 scattering is @xmath28  gev at @xmath29 confidence level  @xcite .
a theoretical analysis has been performed of the processes @xmath26 and @xmath30 for @xmath31  fb@xmath32 .
a transverse momentum greater than 10  gev and a polar angle in the range @xmath33 has been required for the final state particles .    in fig .
[ fig - don ] the ncqft effects on the angular distributions of the final state photons in @xmath30 scattering are shown .
the parameters @xmath34 and @xmath2 are related to the maxwell field tensor  @xcite .
significant deviations from the sm can be observed .
studies of various higgs scenarios show that a photon collider has a unique potential for higgs boson physics over a wide range of masses and model parameters .
excellent b - tagging and good energy resolution are very important for the photon collider to suppress background .
the e@xmath2 option of the photon collider is complementary to the @xmath20 linear collider in discovering effects from non - commutative field theories .
many other topics which can be studied at a photon collider ( e.g. susy , leptoquarks , qcd ) had to be omitted in this short summary .    9 j. gronberg , these proceedings .
ecfa / desy photon collider working group , hep - ex/0108012 ( abs 770 ) .
g. jikia , s. sldner - rembold , nucl .
inst . and meth .
a472 ( 2001 ) 133 ; nucl .
82 ( 2000 ) 373 ( abs 812 ) .
p. nieurawski , a.f .
arnecki and m. krawczyk , hep - ph/0208234 ( abs 665 ) .
p. nieurawski , a.f .
arnecki and m. krawczyk , hep - ph/0207294 ( abs 155 ) .
m. mhlleitner et al .
b508 ( 2001 ) 311 ; d. asner et al .
, hep - ph/0110320 .
e. asakawa , hep - ph/0101234 .
d. asner et al . , hep - ph/0208219 .
s. godfrey , m. doncheski , hep - ph/0111147 ; phys .
d65 ( 2002 ) 015005 ( abs 625 ) .
opal physics note pn500 ( abs 889 ) .
a photon collider will provide unique opportunities to study the sm higgs boson and to determine its properties . 
 mssm higgs bosons can be discovered at the photon collider for scenarios where they might escape detection at the lhc . as an example for the many other physics topics which can be studied at a photon collider , recent results on non - commutative field theories are also discussed .