measurement of the light mesons with the phenix experiment at rhic

Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007 1

Measurement of the light Measurement of the light mesons with the PHENIX mesons with the PHENIX

experiment at RHICexperiment at RHIC

Victor Riabov Victor Riabov

for the Collaborationfor the Collaboration


What do we learn from light mesons (, K, , )

PHENIX experimental capabilities Analyzed decays Detectors and triggers Experimental conditions and background

Results: Spectra and cross checks Integrated yields Particle ratios Nuclear modification factors RAB

Mass Peak Shape

Summary

OutlineOutline


In p+p: Test of pQCD at large momentum transfer

(parton distribution and fragmentation functions) Strangeness content of the event (K,) Non-identical particle ratios (heavier mesons to 0) Reference for heavy ion collisions

In Heavy Ions collisions: Nuclear modification factors, high pT suppression, Cronin effect

An insight at the Chiral Symmetry Restoration (ω,) - line-shape analysis- particle yields in hadron and di-electron decay channels

MotivationMotivation


Analyzed decaysAnalyzed decays

PHENIX acceptance : -0.35 < < 0.35

2 x 90o for two armsBBC (vertex) dz = 0.5cm… 2cm

BBC (trigger) ε = 50%… 92%

DC/PC1 (tracking) dpT/pT ~ 1.0%•pT + 0.7%

EMC (calorimetric) dE/E ~ 8.1%/√E + 3.0%

EMC (t.o.f.) dτ ~ 500 ns

EMC (e/π rejection) ~10

EMC (γ-trigger) 0.4GeV… 2.5GeV

PC3 (matching) 2-4 mm

TOF dτ ~ 100 ns

RICH (e/π rejection) >1000

K+K- BR = 49.2 0.7% e+e- BR = 2.97 0.04% e+e- BR = 7.18 0.12% 0 BR = 8.90 0.25% 0+- BR = 89.1 0.7%

BR = 39.39 0.24% 0+- BR = 22.68 0.35% KS 00 BR = 30.69 0.05%K± using ToF


TriggersTriggersG

amm

aF

inal

m

eso

n

PRC75 (2007) 024909

Minimum bias

EMC-RICH electron trigger

High pT gamma trigger

Due to many particles in the final state of hadron decays even very high pT are affected by the efficiency rising region. Comparison to minimum bias trigger sample at low and intermediate pT is very important


p+p Au+Aud+Au - meson decay modes- meson decay modes

K+K- p+p √sNN=200 GeV K+K- d+Au √sNN=200 GeV K+K- Au+Au √sNN=200 GeV

e+e- Au+Au √sNN=200 GeV

had

ron

ic

lep

ton

ic

PHENIX measures clear signal of K+K- in all collision systemsMeasurement of e+e- is complicated by combinatorial background

e+e- d+Au √sNN=200 GeV

Analysis is not complete

e+e- p+p √sNN=200 GeV


- meson decay modes- meson decay modes0 Au+Au √sNN=200 GeV

ω e+e- Au+Au √sNN=200 GeV

ω

ω e+e- d+Au √sNN=200 GeV

ω

had

ron

ic

lep

ton

ic

PHENIX has measurement of ω in p+p, d+Au & Au+AuMeasurement of ωe+e- complicated by combinatorial background

0+- p+p √s =200 GeV 0 p+p √s =200 GeV

η

ω

p+p Au+Aud+Au

ω e+e- p+p √s=200 GeV



, K, Kss - meson decay modes - meson decay modes

Au+Au √sNN=200 GeV

K s

PHENIX has measurements of in p+p, d+Au & Au+AuMeasurement of Ks in Au+Au are in progress

p+p √s =200 GeV d+Au √s =200 GeV

p+p Au+Aud+Au

Ks 00 p+p √s=200 GeV



p+p Au+Aud+Au

- meson spectra- meson spectra

PHENIX has a complete set of measurement of K+K-

First results on e+e- suffer from lack of statistics e+e- analysis in p+p is in progress


ωω - meson spectra - meson spectra

0+- (0) p+p, d+Au, AuAu √sNN =200 GeV

hadronic

leptonic

PHENIX mapped out high pT ω in p+p, d+Au, produced a first result in Au+Au ω, e+e- in p+p are not ready yet, but the signal there is very clean

ω e+e- Au+Au √sNN=200 GeV

PHENIX Preliminary


Result consistency checksResult consistency checks

Agree

K

Agree

K

Similar analysis

Similar analysis

Agree

nucl-ex/0702046 (QM2006) PRC75 (2007) 024909


- meson yield and temperature- meson yield and temperature

-meson temperature ~same @√sNN=62,200 GeV & is constant with Npart

-meson yield grows both with √sNN & centrality Yield in e+e- channel seems to be higher than that in hadronic channel. More accurate measurements are required to make any conclusions


ηη,K / ,K / 00 ratioratio 2 K0

S 00

nucl-ex/0702046 (QM2006)

PRC75 (2007) 024909

/0 in p+p @√sNN = 200 GeV = 0.48 ± 0.02(stat) ± 0.02(syst) /0 in d+Au @ √sNN = 200 GeV = 0.47 ± 0.02(stat) ± 0.02(syst) /0 in Au+Au @ √sNN = 200 GeV = 0.40 ± 0.04(stat) ± 0.02(syst)Ks/0 in p+p @ √sNN = 200 GeV = 0.45 ± 0.01(stat) ± 0.05(syst)


(()) / / 00 ratioratio

nucl-ex/0611031 acc. to PRC

ω0+- ω0

nucl-ex/0702046 (QM2006)

/0 in p+p Run5 @ √s = 200 GeV = 0.81 ± 0.02(stat) ± 0.07(syst)/0 in d+Au Run3 @ √sNN = 200 GeV = 0.94 ± 0.08(stat) ± 0.12(syst)


Nuclear Modification FactorNuclear Modification FactorAu+Aud+Au

ω

RA

A

RdA for all light mesons compatible with oneRAA for ω & at high pT is below one, same as other mesons


p+p Au+Aud+Au

PHENIX Preliminary PHENIX Preliminary

Mass peak shapeMass peak shape

ω

All measurements at low pT show agreement with PDG ω provides no evidence of change in mass at high pT


PHENIX has measured , Ks, ω and - mesons in hadronic and di-electron decay channels

All mesons behave consistently with other mesons in different collision systems and at different energies.

The baseline measurements (p+p √s=200GeV) exist in hadronic channels and are being analyzed in leptonic channel using accumulated data.

Measured particle ratios at high pT are:/0 in p+p @ √s = 200 GeV = 0.81 ± 0.02(stat) ± 0.07(syst)/0 in d+Au @ √sNN = 200 GeV = 0.94 ± 0.08(stat) ± 0.12(syst)/0 in p+p @ √sNN = 200 GeV = 0.48 ± 0.02(stat) ± 0.02(syst)Ks/0 in p+p @ √sNN = 200 GeV = 0.45 ± 0.01(stat) ± 0.05(syst)

Current di-electron analysis in heavy ion collisions is in progress and needs improvement on the background conditions and more data. Next major step is to take high statistics and high purity di-lepton measurement in (d)A+A

SummarySummary


PHENIX ExperimentPHENIX Experiment

e+

e-

,ω

PHENIX acceptance : -0.35 < < 0.35

2 x 90o for two arms

K+K- BR = 49.2 0.7% e+e- BR = 2.97 0.04 10-

4 e+e- BR = 7.18 0.12 10-

5

0 BR = 8.90 0.25% 0+- BR = 89.1 0.7%


Compare of all ->KK data

Run4

measurement of the light mesons with the phenix experiment at rhic

Documents

p p snn

p p run5

gev e e p p s

progress p p s

e e br

d au au aumeasurement

e e channel

d au snn