International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 12004/8/9-14, CCAST, Beijing
Some Physics Proposal from Barrel STAR-TOF
Yu-Gang Ma
Shanghai Institute of Applied Physics,Chinese Academy of Sciences
(For Chinese STAR-TOF Collaboration)University of Sciences and Technology of China (USTC)
Tsinghua University Shanghai INstitute of Applied Physics (SINAP)
Central China Normal University (CCNU)Institute of Modern Physics (IMP)
Institute of High Energy Physics (IHEP)
International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 22004/8/9-14, CCAST, Beijing
outline
Physics Highlights from 1/120 Barrel TOFWhat can we expect for full STAR-TOF
some simulations for Full TOFPartonic collective dynamicsOpen charm productionResonance physicsSearch for Multi-strange Baryons
Summary
International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 32004/8/9-14, CCAST, Beijing
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International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 42004/8/9-14, CCAST, Beijing
New technology (MRPC, first developed by CERN ALICE) for TOF:
• measurements, cheap, reliable• pion/Kaon separation is extended from 0.6GeV/cto more than 1.6GeV/c• proton/Kaon/pionseparation is extended from 1.1GeV/c to 3GeV/c•Thus cover wider range of (p,K,p) pT (pT spectra, pbar/p)
But only one tray used ( it is only 1/120 coverage of the Barrel TOF(– 0.5<eta<0.)
pK
π
π/K π/Kπ/K/p π/K/p
International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 52004/8/9-14, CCAST, Beijing
Physics Highlights of onePhysics Highlights of one--tray TOF:tray TOF:
1. 1. HadronHadron SpectraSpectra
International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 62004/8/9-14, CCAST, Beijing
Traditional Cronin Effect is not the whole story at RHIC
STAR d+Au from TOFr analysis (USTC+BNL+RICE)
Results on KS, Λ and φ will reach higher pT(SINAP+UCLA)
International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 72004/8/9-14, CCAST, Beijing
For details: see Lijuan Ruan’s Talk in Friday
International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 82004/8/9-14, CCAST, Beijing
Physics Highlights of onePhysics Highlights of one--tray TOF:tray TOF:
2. Heavy Flavor2. Heavy Flavor
International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 92004/8/9-14, CCAST, Beijing
Electron Identification
After PID (cuts in beta), electronsare clearly separated from other particles
Only using TPC dE/dx ID, the electron band crosses with others, which makes the electron ID complicated.
X. Dong, Z.B. Xu, LJ Ruan, J Wu et al
International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 102004/8/9-14, CCAST, Beijing
Bottom:Ratios of the inclusive electrons over the total back-grounds.signal excesses are visible with pT > 1 GeV/c.
The total photonic backgrounds are shown as solid lines.Dashed lines depict the various contributing sources. The fractions were derived from simulations.
International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 112004/8/9-14, CCAST, Beijing
Physics results II: Direct/semilepton Spectra
Combined fit forD0 and electrons
PYTHIA: MSEL = 1, CTEQ5M1
Good agreement between D0 and electrons spectra!
d+Au and p+p do not show significant nuclear effect
L. Ruan QM04X. Dong BNL Seminar For details: see Tai An’s Talk
International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 122004/8/9-14, CCAST, Beijing
With the full With the full coverage of TOFcoverage of TOF
International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 132004/8/9-14, CCAST, Beijing
STAR TPC + TOF (MC)STAR TPC + TOF (MC)
Central (top 10%) collisions
acceptance with TPC:π: ~ 60%K: ~ 60%p: ~ 50%
acceptance with TPC+TOF:> 95% for all particles
S/N for φ reconstruction willincrease by a factor of 5-10⇒ v2 measurement possible
Z. Liu, F. Liu, et al.
International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 142004/8/9-14, CCAST, Beijing
STAR TPC + TOFSTAR TPC + TOF1) TOF will increase V0
reconstruction efficiency. In the case of Ω, a factor of 5 – 10 increase expected in the region pT~ 3-5 GeV/c!
2) TOF will also help future D meson reconstruction –increasing S/N ratios, same way for other resonances. (D0 → K−π+)(D0-bar → K+π−)
3) In the case for φ, a factor of 5-10 increase in S/N ratio is expected. φ=>K + + K - (49.1%)
H. Long et al.
International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 152004/8/9-14, CCAST, Beijing
STAR TPC + TOFSTAR TPC + TOFΩ v2 measurements
For integrated Ω v2 : needs ~ few 106 MiniBias events. More events without TOF ⇒ Multi-years running.
pT dependence Ω v2:for <20% around pT ~ 5 GeV/c, needs ~ few 10th 106 MiniBiasevents with TOF⇒ almost impossible without TOF
STAR 200 GeV results:T = 0.45 GeVdN/dy = 0.64, sum of Ω- and Ω+
< v2 > ~ 8%all are usable events (1.5 -3 factor)
International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 162004/8/9-14, CCAST, Beijing
TOF and Λ Hyperon
1.1 1.11 1.12 1.130
100
200
)2
inv_mass ( GeV/c
Embedded Data:Λ reconstruction with and without PID information!A Factor of 3 !!
0
100
200
300
400
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
Λ
TPC only
TPC + TOF barrel
pt (GeV/c)R
esco
nstr
ucte
d Λ
Yie
lds \T
ex2alk\2002\ST
AR
\TX
Sept02igures\lam
bda_eff.kumac//
( )Tmmf ttSB /exp −⋅∝Input spectrum:T = 350 MeV
International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 172004/8/9-14, CCAST, Beijing
A Critical Test for Recombination
Duke Group, PLB 587, 73 (2004)
Ω
φ
how about φ, Ω, D, J/Ψ v2(p⊥) ?
Need Full TOF for good efficience and statistics
jets
J/ψ, D
Ω
φ
Ξ
Λ
π, K, K*
∆, p
d, HBT
elliptic flow velliptic flow v22
radial flowradial flow ββTT
Q2
time
partonic scatterings?early thermalization?
TTCCTTchch
TTfofo
International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 182004/8/9-14, CCAST, Beijing
115M115M4>pT>6.
42M85M2>pT>4.
23M59MpT>2.
2.6M12MAll pT
With TOFWithout TOF
D0 Sensitivity in pT
V. Greco, C.M. Ko, R. Rapp, nucl-th/0312100
Heavy Quark Flow Effects?
Important Measurement: Open CharmTOF helps by a factor of ~5 (all PT)TOF + Active Pixel Sensitive: x8Other Open Charm States Possible only with TOF
Full Coverage needed
International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 192004/8/9-14, CCAST, Beijing
Time scale of resonance stateResonance K*(892) ρ(770) f0(980) φ(1020) ∆(1232) Λ(1520) Σ(1385)Decay channel K π π π π π K K ee p π p K Λ πBranching Ratio % ~100 ~100 dominant 49.2 0.3 >99 22.5 88.2Width [MeV] 50.7 150 40 to 100 4.46 ~120 15.6 35.8Life time [fm/c] 4 1.3 40 ~1.6 13 5.6
Resonance Parent PT(GeV/c) TPC+TOFK*0 0-1 2.0K*0 1-2 1.85K*0 2-3 1.74K*0 3-5 1.39______________________φ(1020) 0-2 5.0φ(1020) 2-5 3.42___________________________Λ(1520) 0-1.6 11.4
Chemical Freeze-out--- formation of hadrons
Kinetic Freeze-out--- Interaction ceases
Increasing factor for statistical significance of the signal
International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 202004/8/9-14, CCAST, Beijing
search for search for didi--omegaomegaZ.Y. Zhang et al., Phys. Rev. C 61, 065204 (2000); Phys. Rev. C66, 015205 (2002)3 body decay:
2 body decay:
A chrial SU(3) model and analyses of the symmetry properties of two-baryon systems, some features:
A deeply bound, Eb ~ 100MeV;A compact object, Rrms~0.63fm, <<Rdmay be six strange quark state rather than a di-baryon configuration
Phenomenological estimation (coalescence/statistical): yield 10-4_10--7/central Au-Au; Full barrel TOF ~ 100M central AuAu events needed.
International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 212004/8/9-14, CCAST, Beijing
Relativistic Heavy Ion Collisions & Full TOF related physics
1) Initial Condition - baryon transfer- ET production- partons dof- gluon dynamics
2) System Evolves- parton/hadron
expansion- QCD phaseQUARK-GLUON PLASMA?
3) Bulk Freeze-out- hadrons dof- interactions stop
Time
Q2: partonic collectivity? QGP?
Tools: • Transverse Flow• Elliptic Flow
Problem:• Flow is additive
Approach:• Probes “insensitive” to hadronic stage (φ,Ξ,Ω,D,J/Ψ)
S.Bass
Q3: Resonance Physics?Q4: Multi-strange baryons?
Q1: Open charm: gluon dynamics?
Also we are interested in Event-by-event fluctuation and HBT physics etc.
International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 222004/8/9-14, CCAST, Beijing
ConclusionConclusionIn order to know about the elliptic flow of φ ,Ω, D, J/Ψ, Full TOF is necessary for good efficiency and statistics.In order to improve the measurements of Open Charm, TOF helps by a factor of ~5 (all PT) and Full Coverage neededIn order to investigate the hadronic evolution dynamics, TOF increases important factor for statistical significance of the resonance production.TOF will significantly enhance the hyperondetection efficiency. RHIC provides a unique environment for possible production of multiply strange di-baryons.
International CCAST Summer School and Workshop on QCD & RHIC Physics Yu-Gang MA 232004/8/9-14, CCAST, Beijing
The EndThe End
Thank you!Thank you!
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