Recent results from RHIC experiments -- QGP search and the spin program --

1
Recent results from RHIC experiments-- QGP
search and the spin program --

• ????
• ??-BNL??????

2
Outlook
3
RHIC????

• QGP??
• PHENIX, STAR, PHOBOS, BRAHMS
• Spin asymmetry
• PHENIX, STAR, pp2pp
• pp ???????
• pp2pp

4
Relativistic Heavy Ion Collider

• ??3.83 km, 2??????????????????
• ??100 GeV ???250 GeV ??????
• 2003??? 100 GeV ???????
• 5??????? PHENIX/STAR/PHOBOS/BRAHMS/pp2pp

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QGP ??

• ?????????????
• ??/??????????????????
• ???QCD???????????
• ????, ????, ??????????

• ????????????
• 1970?????????
• Bevalac (LBNL), SIS(GSI), AGS(BNL), SPS(CERN)
• ????BNL???? Relativistic Heavy Icon Collider
  (RHIC) ????????

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QGP??????

• ????????????
• QGP?????
• ???????
• ??????????/QGP????
• ????????????????????????????
• ??
• ???????/QGP?????????
• ????
• ????? ???????, QGP????????
• ????????? ?????????
• ????
• ??????
• ??, ????, ????
• ????????????
• ?????????????

7
??????????

• ????????
• ?????? (v2)
• ?????????(?sNN120GeV)???????????v2
• ????????????????????
• ?????
• ?? Tch170MeV
• QGP????Chemical freeze-out???
• ????????????????
• ??????
• ???????????????????
• ??????????????????
• ??????????pp?????
• high pT?????????
• dAu??????????
• Back-to-Back Jet ???
• Jet????????pp,dAu,AuAu??????
• AuAu??????????????
• High pT??????????????????????

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????????????

• ??????/???????????
• ????????
• ?????????????????????????????????????????????????
  ????????
• ?????
• ????/????????????
• ???????????????

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????????????(Low pT)

• ?????????????????
• ????(??????????)
• ????
• radial flow
• ????
• radial flow ? anisotropic flow

In Perfect Hydrodynamical source, v2 is
proportional to e
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????????????(high pT)

• High pT ???????????????????????
• ??????????????????????
• ???????????????????????(??????)???v2???
• ??? M. Gyullasy, I.Vitev, X.N.Wong,
  PRL86(2001)2537

??????????
??????????

• ???????????????????????????????????????????
• ????????????????

• ????????????????????????????????????
• ???????????????

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??????? v2 (low pT) vs. ?????

• 130GeV AuAu ??
• v2???
• ????????????
• ???????????????????????
• ???????????????????????

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v2????????? (low pT)

• ??????????????
• RHIC????????v2??????
• ?????????????????????????

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???????????v2 ? pT ???

• pTlt2GeV/c ?????????????????
• High pT????????v2??????

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High pT ?? v2

• pT8GeV/c???????v2
• ????pT??v2???????
• ???????????
• v2??????????
• ??????????

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?????????????????

• ?????????????????
• J. Rafelski, Phys. Lett. B190 (1987) 167

• ???????????????????????
• ????????
• ???????????
• Tch, mB, ms
• gs
• gs1 ? ????????????????????

Lattice QCD predictions
central collisions
SPS
Baryon Chemical Potential mB GeV
parton-hadron phase boundary
Neutron star
ltEgt/ltNgt1GeV, J.Cleymans and K.Redlich, PRC60
(1999) 054908
From M.K.s talk in the first joint meeting of
JPS and DNP, Hawaii, 2001 SQM2003
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RHIC????????????????????
17
????????

• ???????????????4??????? (Tch, mB, ms and
  gs)????????!

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pT Distributions (pTlt2GeV/c)

• Bevalac??SPS???????????????
• ????????pT ?????? pp ????????????????????
• ???????????
• ????????
• ????????
• ?????????????????????
• ???????????

NA44 PRL78 (1997) 2080
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Tth?flow?????????
200 GeV AuAu
130 GeV AuAu
Blastwave model fit for STAR data From QM2002,
M.K.s poster
p-
K-
K
Data O. Barannikova/F. Wang QM2002 Talk
STAR preliminary
Centrality 0-5 5-10 10-20 20-30 30-40 40-50
50-60 60-70 70-80
pT GeV/c
Blastwave model fit for STAR data From QM2002,
M.K.s poster
STAR nucl-ex/0306029
pT GeV/c
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??????????

• Thermal (Kinetic) freeze-out ???AGS???????????????
  ???????
• Flow ????RHIC??????????????

PHENIX
STAR
21
???????????????????????

• RHIC???????

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????????????????????

• ??????????High pT???????????
• ??????
• ?????
• pp??????

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??????? RAA

• ???????????
• RAA lt 1 at low pT (???????????)
• RAA 1 at high pT (???????????????)
• ?? (??????, ???Cronin??)
• RAA lt 1 (gt 1) at high pT

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Physical Review Letters???

• Physical Review Letters, Vol.91, 072302-072305
• Latest results of the PHENIX, PHOBOS, BRAHMS
  STAR Collaborations from 200-GeV per nucleon
  gold-gold and deuteron-gold nuclear collisions.
  In the Au-Au data, high-transverse-momentum
  particles are suppressed (red data in PHOBOS
  BRAHMS) and there is only one peak in the
  pair-correlation plot (STAR) both results are as
  expected if a quark-gluon plasma forms. A QGP is
  not expected in d-Au collisions and this data
  show no high-pT suppression (PHENIX) and two
  peaks.

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AuAu/pp ? dAu/pp

• AuAu?????? high pT?????????????????????????????
  ????

26
???????? ??

• ?????????????????????????????????????????????????
  ?

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QGP????????????????

• ????????
• ?????? (v2)
• ?????????(?sNN120GeV)???????????v2
• ????????????????????
• ?????
• ?? Tch170MeV
• QGP????Chemical freeze-out???
• ????????????????
• ??????
• ???????????????????
• ??????????????????
• ??????????pp?????
• high pT?????????
• dAu??????????
• Back-to-Back Jet ???
• Jet????????pp,dAu,AuAu??????
• AuAu??????????????
• High pT??????????????????????

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?????????

• dN/dh, dET/dh
• ??????????
• ???????????????
• ???????????????
• ltpTgt, Isospin
• ???????
• p/K/p?????????????????
• ???????
• ???????
• ?????????????????????????????
• ?????
• ??????????????????????
• ????
• ????
• J/?, ?
• ??????????????(?)

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RHIC?????????????????????
30
?????

• ?????????????

Proton Spin
Gluon Spin
Orbital Motion

• ??????????? ???????????????????????
• ????
• ??
• ??

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RHIC???????

• ??pp??????????????????????????
• Spin Structure of the Nucleon
• Proton Spin Sum Rule
• Transversity Distributions
• Spin Dependence of Fundamental Interactions
• Parity Violating Interaction
• T Violation ? CP Violation ( CPT 1 )
• Spin Dependence of Fragmentation
• e.g. Lambda fragmentation function
• Spin Dependence in pp elastic scattering

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?????????????????RHIC
33
?????????

• ??????????
• ??????????????????????
• ????????????????????
• ?????????
• ?????????

IP4 and IP10
STAR and IP12
PHENIX and PP2PP
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???????? (PHENIX)
Extension 180nb-1/wk, Polarization between 0.25
and 0.3. Extended periods with polarization
above 0.35 earlier in the run. Goal
500nb-1/week at P0.4
2 IRs
STAR rotators
pp2pp
ZDC
Begin of Physics
BBC
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Factorization and Universality
Hard Scattering Process

• Factorization ensures that parton distribution
  function at
• DIS
  and pp are the same objects

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?????????
signature
Processes
High-pT prompt ?
Gluon Compton

Charmonium
ee-, ??-
Open Heavy Quark Light Flavor
ee-, ??- ,e?,e, ?,, Jet(Charged Hadrons, p0)

High-pT ? , e, ee-, ??-
W Z boson,Drell-Yan)
W
p-p?????????????????????????
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??????????
Relative Luminosity
Beam polarization (Blue, Yellow) Spin dependence
of process of interest Luminosity
parallel - anti-parallel

• Run3??????
• ?????????? p0 ALL (???????????)
• ??????????? 26
• N, N- p0??
• ?????????????? ?R2.5?10-4(??????)

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Relative Luminosity

• Special scalers used
• Counts live trigger in each bunch crossing
• 4 inputs for syst. error study
  Beam Beam Counter and Zero Degree
  Calorimeter used different kinematical region,
  different physics signals
• Systematic error study through comparison of
  counts from different detectors
• look at ratio of 2 detector scalers
  crossing-by-crossing
• a(i) NA(i)/NB(i)
• Ratio should be the same for all crossings
  (constant) if
• NA(i) L eA and NB(i) L eB
• B is always the counts from the Beam-Beam Counter
  (BBCLL1), A is one of the other scalers.
• Fit this by the expected pattern
• a(i) C1ALLP1(i)P2(i)
• C, ALL are the fitting parameters.
• c2 is a very important check of systematic errors

ALL vs fill
30
?2/NDF vs ?(ALL)
20
10
Not so good, but
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Relative Luminosity (contd)
Vertex(????)?????????????????????????
After vertex correction
ALL vs fill
ZZDC/ZBBC vs z-vertex width
?
?2/NDF vs ?(ALL)
3
2
1
Now ?2/NDF?1
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Relative Luminosity Run3????

• ?R2.5?10-4???(???????)??
• Pessimistic estimation limited by ZDC statistics
  (30 times less than BBC statistics used in
  Relative Luminosity measurements)
• ???????????? p0 ALL ?????0.2??
• ??????????? 26
• ALL of BBC relative to ZDC consistent with 0
  (lt0.2)
• Strong indication that both ALLs are zero (very
  different kinematical regions, different physics
  signals)

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??????????

• High pT ??????????????????
• ?????? ?? 1.4 GeV/c
• ???????????? 110
• ????????????? 42.7M (0.215 pb-1)
• ?????????? ?ltPbPygt26
• ???????????
• ??????? ?0 ????? ? low pT?????
• High pT ????????????????

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Photon trigger efficiency for ?0

• Pi0 efficiency plateaus for pTgt4 GeV/c
• Limitted efficiency at pTlt4 GeV/c
• 1-2 GeV/c 6
• 2-3 GeV/c 60
• 3-4 GeV/c 90
• 4-5 GeV/c 95
• Monte Carlo reproduces Data well

Data MC
?0 pT (GeV/c)
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??0 p0 reconstruction
pT 1.5-2.0 GeV/c
mass GeV/c2
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?0 ?????
Run-2 results
submitted to PRL, hep-ex/0304038

• Results consistent with pQCD calculation
• Favours a larger gluon-to-pion FF (KKP)
• Important confirmation of of theoretical
  foundations for spin program
• Run3 results reproduces Run2 results
• Confirms the Run-3 data reliability and
  consistency
• Run3 data reaches even higher pTs results will
  be finalized soon

9.6 normalization error not shown
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?0 ??????????

• Results obtained for four pT bins from 1 to 5
  GeV/c
• p0 peak width varies from 12 to 9.5 MeV/c2 from
  lowest to highest pT bins
• Background contribution under p0 peak for ?25
  MeV/c2 mass cut varies from 45 to 5 from the
  lowest to highest pt bins

2-3 GeV/c B.G.17
1-2 GeV/c Background 45
3-4 GeV/c B.G.7
4-5 GeV/c B.G.5
46
?0 ???????
N?0 ?25 MeV/c2 around ?0 peak (and also ?15 and
?35 MeV/c2 for cross checks) Nbck1 Two 50
MeV/c2 wide areas adjacent to ?0 peak Nbck2
250 MeV/c2 wide area between ?0 and ? peaks
N?0 and Nbck accumulated statistics
pT GeV/c N?0 15 MeV/c2 N?0 25 MeV/c2 N?0 35 MeV/c2 Nbck1 Nbck2
1-2 1278k 1777k 2129k 1470k 3478k
2-3 874k 1059k 1146k 335k 989k
3-4 176k 201k 208k 27k 83k
4-5 34k 38k 39k 3.9k 12k
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?0 ALL???
???????fill???????ALL
1-2 GeV/c ALL -2.81.2 ?2/ndf 64/48 2-3
GeV/c ALL -2.21.5 ?2/ndf 34/48 3-4
GeV/c ALL -0.23.3 ?2/ndf 49/48 4-5
GeV/c ALL -2.37.4 ?2/ndf 39/48
1-2 GeV/c
2-3 GeV/c
4-5 GeV/c
3-4 GeV/c
48
?0 ALL
?0bck 15 MeV/c2
?0bck 25 MeV/c2
?0bck 35 MeV/c2
Bck1
Bck2
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200 GeV pp ???? ?0 ALL
pT GeV/c (rbck) (Background subtracted)
1-2 -0.028?0.012 (45) -0.006?0.014 -0.046?0.025
2-3 -0.022?0.015 (17) -0.035?0.027 -0.019?0.019
3-4 -0.002?0.033 (7) 0.094?0.092 -0.009?0.036
4-5 -0.023?0.074 (5) 0.38?0.24 -0.045?0.079

• Polarization scaling error ?P 30
• is not included
• Enters to ALL quadratically
• Analyzing power
• AN(100 GeV) AN(22GeV) is assumed
• ?P30 combined stat. and syst. error
• for AN(22GeV) (AGS E950)

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???

• QGP??
• ????????
• ??????????????????
• ?????????????????????????????????????
• ??????????????
• ???????
• ??
• ????
• J/?, ?
• ???????????????????????????
• ?????
• ????????????pp???????????
• ??????????????????????????????
• ??????
• ???????????
• ???????????????????

51
backup
52
Ideal Hadron Gas Model
Refs. J.Rafelski PLB(1991)333 J.Sollfrank et al.
PRC59(1999)1637
Hadron resonance ideal gas
Particle density of each particle
Qi 1 for u and d, -1 for u and d si 1 for s,
-1 for s gi spin-isospin freedom mi particle
mass
Tch Chemical freeze-out temperature mq
light-quark chemical potential ms strangeness
chemical potential gs strangeness saturation
factor
All resonances and unstable particles are decayed
Comparable particle ratios to experimental data
53
Ideal Hadron Gas Model (cont.)

• Hadron resonance ideal gas
• including higher mass resonances(?1.7GeV)
• For mid-rapidity, no requirement of
• Strangeness neutrality
• Charge/Isospin conservation

?, ?, ?, ?, ?, ?, f0(980) , a0 (980), h1(1170),
b1 (1235), a1 (1260), f2(1270), f1 (1285),
?(1295), ?(1300), a2(1320), f0(1370), ?(1440),
?(1420), f1 (1420), ?(1450), f0 (1500), f1
(1510), f2(1525), ?(1600), ?2(1670), ?(1680),
?3(1690), fJ(1710), ?(1700) p, n, N(1440),
N(1520), N(1535), N(1650), N(1675), N(1680),
N(1700) ?(1232), ?(1600), ?(1620), ?(1700) K,
K, K1(1270), K1(1400), K(1410), K0(1430),
K2(1430), K(1680) ?, ?(1450), ?(1520),
?(1600), ?(1670), ?(1690) ?, ?(1385), ?(1660),
?(1670) ?, ?(1530), ?(1690) ?
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Brahms dAu and AuAu
55
star, 200, dAu
PRL91(2003)072304
56
Transversity
Helicity flip amplitude Chiral odd function
not accessible in inclusive DIS
Naively for non-relativistic
quarks
Relativity breaks rotation symmetry. Soffers
bound Need not to be small!
Possibly Gluon (spin1) cannot flip proton
(spin1/2) helicity does not mix with
gluons under evolution Non-relativistic
Relativistic First Lattice QCD
result
S. Aoki, M. Doui, T. Hatsuda and Y. Kuramashi
Phys.Rev. D56 (1997)433 More recently S.
Capitani et.al. Nucl. Phys. B (Proc. Suppl.) 79
(1999) 548
57
Transversity Measurements at Polarized pp
polarized DIS ee-
pp BNL - Star/Phoenix/Phobos
ep DESY-Hermes CERN-Compass (BNL eRHIC,
DESY Tesla-N)
ee CERN-Delphi, KEK Belle, etc
58
HERMES result on azimuthal asymmetry
l
p
Non-zero transverse polarization!
Results shows that both Collins Function
and Transversity are non zero, and rather large