Systematic Study of High-p T Direct Photon Production with the PHENIX Experiment at RHIC
System Size and energy dependence of photon production measured with the PHENIX experiment at RHIC
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PHENIX Detector Central Arms Coverage (E&W) -0.35< y < 0.35 30 o <|f |< A complex apparatus to me asure: Hadrons, Muons, Ele ctrons, Photons Muon Arms Coverage (N&S) 1.2< |y| <2.3 -180 o < f < 180 o View From Beam View From Side For the Quark Matter 2006 Conference at Shanghai, China, Nov 13-20, 2006 System Size System Size and energy dependence and energy dependence of of p p hoton production measured hoton production measured with with the PHENIX the PHENIX experiment at RHIC experiment at RHIC Takao Sakaguchi, Brookhaven National Laboratory, for the PHENIX Collaboration Nuclear Effect Prompt Prompt and and 0 product product ion in ion in -Be, p-Be, -Be, p-Be, -Cu, p-Cu (Tevatro -Cu, p-Cu (Tevatro n E706) n E706) Cronin effect both in Cronin effect both in and and 0 ! ! : k : k T broadening, broadening, 0 : : k k T broadening + re broadening + re combination combination PRD72, 032003(2005) Center-of-mass energy, and xT region: • RHIC: s NN =200GeV, xT ~0.04- 0.25 • E706: s NN =32-40GeV, xT~0.2- 0.5 CERN (WA98) results CERN (WA98) results A dedicated experiments for direct p A dedicated experiments for direct p hoton search in relativistic heavy Ion hoton search in relativistic heavy Ion collisions. collisions. ( ( PRL 85 (2000) 3595) PRL 85 (2000) 3595) s s NN NN =17.3Ge =17.3Ge V V Data can be either explained by kT-s Data can be either explained by kT-s mearing or higher initial temperature mearing or higher initial temperature Any data did not see pT>4GeV, where Any data did not see pT>4GeV, where pQCD photons dominate pQCD photons dominate No information on kT does not allow No information on kT does not allow us to resolve the issue. us to resolve the issue. Recent data points at ~100MeV availa Recent data points at ~100MeV availa ble from WA98. ble from WA98. By analysis of correlation strength By analysis of correlation strength in interferometry, in interferometry, PRL93(2004)022301 PRL93(2004)022301 WA98 data and theoretical interpretation PRC69(2004)014903 Good thing about photons! •Compton scattering of quarks and gluon s: q(q)gq(q) •Annihilation of quarks: qqg •NLO: Bremsstrahlung, NNLO: Fragment… No strong interaction once produced! Best prob e bringing thermodynamical Information out of the system (Initial temperature, degree of fre edom, time profile, etc.) What we learn from system and energy dependence of photon production? •Photon: hard + soft + hard-soft interplay •Results from different systems disentangle photon sources •Results from different energies give different signal to background ratios Leading order (LO) Next to Leading order (NLO) Au+Au s NN =200GeV •Brand New high pT direct photon spectra up to 18GeV /c •NLO pQCD calculation w orks relatively well. •Intermediate pT region show is of interest (5- 10GeV/c) •For pT<3GeV/c, thermal ph oton contribution looks do minant •Jet-Photon conversion can describe the data for pT>3 GeV/c •Uncertainty of p+p and d+ Au result can overcome the se contributions •Upcoming data disentangle s the fraction of soft and hard component •AuAu 62GeV •CuCu 200, 64GeV Initial hard scatt ering: p+p 200Ge V •Calculable by NLO p QCD (pT>5GeV/c) •Comparison with p+p 200GeV collisions da ta •Calculation agrees data within error Estimate of background photons from sources listed above is also essential The baseline in this collision energy Good thing about CERN: less Jet production cross-section-> less pi0 background PHENIX Data! : d+A 200GeV •Expect kT broadening as is seen in E706 •Probably, some hint is here •Still in work to red uce systematic error A compilation on photons, PRC 69(2004)014903 1.Jet-Photon conversion due to secondary scattering of hard-scattered parton (4< p T <7GeV/c) 1.A prediction says almost same amount as pQC D contribution is expected 2.Thermal photon production in QGP(1<p T <3 GeV) 1.~10% of ’s from hadron decays 3.Hadron-gas interaction (p T <1GeV/c) 1. () (), K* K PRC 72(2005)014906 nucl-th/0507018 ) 0 ( Im 2 3 M f p d dR E em B em ) 0 ( Im 3 2 4 M f M p d dR em B em ee f B : Bose dist. em : photon self energy photons dileptons Possible contribution in heavy ion collisions (Au+Au, CuCu) Different Ncoll and Npart dependence! NLO pQCD: L.E.Gordon and W. Vogelsang, PRD48(1993)3136 pQCD is LO! Low to Mid-pT region data (/ 0 double ratio) p+p Data to fit function used for making RAA Latest direct photon spectra RAA’s / 0 double ratio
description
photons. Good thing about photons!. dileptons. No strong interaction once produced! Best probe bringing thermodynamical Information out of the system (Initial temperature, degree of freedom, time profile, etc.). Leading order (LO). f B : Bose dist. em : photon self energy. - PowerPoint PPT Presentation
Transcript of System Size and energy dependence of photon production measured with the PHENIX experiment at RHIC
PHENIX Detector
Central ArmsCoverage (E&W) -0.35< y < 0.35 30o <|f |< 120o
A complex apparatus to measure: Hadrons, Muons, Electrons, Photons
Muon ArmsCoverage (N&S) 1.2< |y| <2.3 -180o < f < 180o
View From Beam
View From Side
For the Quark Matter 2006 Conference at Shanghai, China, Nov 13-20, 2006
System SizeSystem Size and energy dependence and energy dependence of of pphoton production measured hoton production measured withwith the PHENIX experiment at RHIC the PHENIX experiment at RHIC
Takao Sakaguchi, Brookhaven National Laboratory, for the PHENIX Collaboration
Nuclear Effect
Prompt Prompt and and 00 production in production in -Be, p-Be, -Be, p-Be, -Cu, p-Cu (T-Cu, p-Cu (T
evatron E706) evatron E706)
Cronin effect both in Cronin effect both in and and 00!!: k: kTT broadening, broadening, 00: k: kTT bro bro
adening + recombinatioadening + recombinationn
PRD72, 032003(2005)
Center-of-mass energy, and xT region:•RHIC: sNN=200GeV, xT ~0.04-0.25•E706: sNN=32-40GeV, xT~0.2-0.5
CERN (WA98) resultsCERN (WA98) resultsA dedicated experiments for direct photon search A dedicated experiments for direct photon search in relativistic heavy Ion collisions. in relativistic heavy Ion collisions.
((PRL 85 (2000) 3595)PRL 85 (2000) 3595)ssNNNN=17.3GeV=17.3GeV
Data can be either explained by kT-smearing or Data can be either explained by kT-smearing or higher initial temperaturehigher initial temperatureAny data did not see pT>4GeV, where pQCD phAny data did not see pT>4GeV, where pQCD photons dominateotons dominateNo information on kT does not allow us to resolvNo information on kT does not allow us to resolve the issue.e the issue.Recent data points at ~100MeV available from WRecent data points at ~100MeV available from WA98. A98. By analysis of correlation strength in interferometBy analysis of correlation strength in interferometry,ry,
PRL93(2004)022301PRL93(2004)022301WA98 data and theoretical interpretationPRC69(2004)014903
Good thing about photons!
•Compton scattering of quarks and gluons: q(q)gq(q)•Annihilation of quarks: qqg•NLO: Bremsstrahlung, NNLO: Fragment…
No strong interaction once produced! Best probe bringing thermodynamical Information out of the system (Initial temperature, degree of freedom, time profile, etc.)
What we learn from system and energy dependence of photon production?
•Photon: hard + soft + hard-soft interplay•Results from different systems disentangle photon sources•Results from different energies give different signal to background ratios
Leading order (LO)
Next to Leading order (NLO)
Au+Au sNN=200GeV•Brand New high pT direct photon spectra up to 18GeV/c
•NLO pQCD calculation works relatively well.•Intermediate pT region show is of interest (5-10GeV/c)
•For pT<3GeV/c, thermal photon contribution looks dominant
•Jet-Photon conversion can describe the data for pT>3GeV/c
•Uncertainty of p+p and d+Au result can overcome these contributions
•Upcoming data disentangles the fraction of soft and hard component
•AuAu 62GeV•CuCu 200, 64GeV Initial hard scatte
ring: p+p 200GeV
•Calculable by NLO pQCD (pT>5GeV/c)
•Comparison with p+p 200GeV collisions data
•Calculation agrees data within error
Estimate of background photons from sources listed above is also essential
The baseline in this collision energy
Good thing about CERN:less Jet production cross-section-> less pi0 background
PHENIX Data! : d+A 200GeV
•Expect kT broadening as is seen in E706
•Probably, some hint is here
•Still in work to reduce systematic error
A compilation on photons, PRC 69(2004)014903
1.Jet-Photon conversion due to secondary scattering of hard-scattered parton (4<pT<7GeV/c)1. A prediction says almost same amount as pQCD contributi
on is expected2.Thermal photon production in QGP(1<pT<3GeV)
1. ~10% of ’s from hadron decays3.Hadron-gas interaction (pT<1GeV/c)
1. () (), K* KPRC 72(2005)014906
nucl-th/0507018
)0(Im23
Mfpd
dRE em
Bem
)0(Im324
MfMpd
dRem
Bemee
fB: Bose dist. em: photon self energy
photons
dileptons
Possible contribution in heavy ion collisions (Au+Au, CuCu)
Different Ncoll andNpart dependence!
NLO pQCD: L.E.Gordon and W. Vogelsang, PRD48(1993)3136
pQCD is LO!
Low to Mid-pT region data (/0 double ratio)
p+p Data to fit function used for making RAA
Latest direct photon spectra
RAA’s
/0 double ratio
