Yuriy Riabov QM2006 Shanghai Nov.19, 2006 1 Measurement of the leptonic and hadronic decays of and...

Yuriy Riabov QM2006 Shanghai Nov.19, 2006

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Measurement of the leptonic and Measurement of the leptonic and hadronic decays of hadronic decays of and and ωω mesons at RHIC by PHENIXmesons at RHIC by PHENIX

Yuriy Riabov Yuriy Riabov

for the Collaborationfor the Collaboration


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PHENIX capability to measure ω &

Experimental conditions

Results: Spectra Integrated Yields Particle Ratios & RAB

Mass Peak Shape

Summary

OutlineOutline


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PHENIX ExperimentPHENIX Experiment

K+

K-

PHENIX acceptance : -0.35 < < 0.35

2 x 90o for two arms

BBC (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 10-

4 e+e- BR = 7.18 0.12 10-

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


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e+

e-

,ω











TOF dτ < 100 ns


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

4 e+e- BR = 7.18 0.12 10-

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


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0

ω











TOF dτ < 100 ns


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

4 e+e- BR = 7.18 0.12 10-

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


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0

ω

+

-











TOF dτ < 100 ns


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

4 e+e- BR = 7.18 0.12 10-

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


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

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

e+e- d+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


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

0+- 0 p+p √s =200 GeV 0 Au+Au √sNN=200 GeV

ω e+e- d+Au √sNN=200 GeV ω e+e- Au+Au √sNN=200 GeV

ω ω

had

ron

ic

lep

ton

ic

PHENIX has first measurement of ω in p+p, d+Au & Au+AuMeasurement of ωe+e- is as complicated as for in the same mode

η

ω


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p+p Au+Aud+Au - meson spectra- meson spectra

d+Au √sNN=200 GeV Au+Au √sNN=62 GeV √sNN=200 GeV

d+Au √sNN=200 GeVAu+Au √sNN=200 GeV

had

ron

ic

lep

ton

ic

PHENIX has a complete set of measurement of K+K- in TOF region First results on e+e- lack statistics.


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ωω - meson spectra - meson spectrap+p Au+Aud+Au

0+- (0) p+p √s =200 GeV d+Au √sNN =200 GeV 0 Au+Au √sNN=200 GeV

ω e+e- Au+Au √sNN=200 GeVρ,ω, e+e- p+p √s=200 GeV

had

ron

ic

lep

ton

ic

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

PHENIX Preliminary

nucl-ex/0611031


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- meson yield and temperature- meson yield and temperatureh

adro

ni

cle

pto

ni

c

T approximately the same at√sNN=62, 200 GeV and is constant with Npart

Yield grows both with √sNN and centrality


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ωω//00 ratioratioh

adro

ni

cPHENIX Run3

PHENIX Run5

ω results in Run3&5 are consistentω/π0 ratio is flat above pT = 2.5 GeV/cboth in p+p and d+Au and close to the ratio at lower √s PYTHIA predicts slightly higher value

/0 in p+p Run3 @ √s = 200 GeV = 0.85 ± 0.05(stat) ± 0.09(syst) final

/0 in p+p Run5 @ √s = 200 GeV = 0.81 ± 0.02(stat) ± 0.07(syst) preliminary

/0 in d+Au Run3 @ √sNN = 200 GeV = 0.94 ± 0.08(stat) ± 0.12(syst) final

nucl-ex/0611031


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Nuclear Modification FactorNuclear Modification Factor

ω

RA

A

Rc

pRωdA √sNN = 200 GeV (final)

MB: 1.03 ± 0.11 ± 0.09

(0%-20%): 0.87±0.18 ± 0.08

RωAA √sNN = 200 GeV (prelim)

Peripheral: 1.11 ± 0.27

MB & 0%-20%: 0.37 ± 0.12

RdA for all light mesons are around 1RAA for ω & at high pT is below one, same as other mesons

Au+Aud+Au

nucl-ex/0611031


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p+p Au+Aud+AuMass peak shapeMass peak shape

ωSTAR: PRL 92, 092301 (2004)

All measurements at low pT show agreement with PDG.ω measurements show no evidence of mass modification at high pT

nucl-ex/0611031


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HBD for PHENIXHBD for PHENIX

e+

e-

,ω

e+e- BR = 2.97 0.04 10-4 e+e- BR = 7.18 0.12 10-5

Measurements in di-electron channels are complicated because of the combinatorial background coming from 0 decays. The HBD detector installed in PHENIX in Run 7 vetoes electrons which have close partner to reduce the background. We expect to suppress background level by a factor of ~ 100


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PHENIX measured ω & production in hadronic channels. Both mesons behave consistently with other mesons in different collision systems at different energies.

Preliminary results exist on ω & meson production in e+e- decay channel. Current situation needs improvement on the background conditions and more data.

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

Next major step is to take high statistics and high purity dilepton measurement in d+A and A+A.

SummarySummary


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ωω 00 invariant mass spectra invariant mass spectrae+p e+C

0 e+p Ee =2.8 GeV e+C Ee =2.8 GeV

Peaks at low masses in the channel may be in part , explained by correlated background from eta, pi0 Ks …

CB

EL

SA

/T

AP

S

|p|< 500 MeV/c |p|< 500 MeV/c

Pre

lim

ina

ry s

ho

wn

by

V.

Me

tag

on

No

v.1

6,

20

06

P

len

ary

ref.

to

D.

Trn

ka

(G

ieß

en

) p

riv

. c

om

.c

PH

EN

IX

0 p+p √s =200 GeV

M.Lutz Nucl. Phys. A706 431 (2002)

0 peak

Other peaks seen in p+p… Au+Au

Correlated background reproduced from the data

Part, not all of it!!!


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& K& K√sNN


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MinBias, dAu, 200 GeV

PHENIX preliminary1/2

mT d

N/d

mTd

y (G

eV

/c2)-

2

dAuKK

dAuee

MT(GeV/c2)


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KK in pp collisions: Comparison with STAR


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Comparison of ->KK data

Results are self consistent in PHENIX

The gap between PHENIX and STAR exist in different energies and systems

Yuriy Riabov QM2006 Shanghai Nov.19, 2006 1 Measurement of the leptonic and hadronic decays of and...

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