Strange quark dynamics on hot dense matter under the extreme condition

1
Strange quark dynamics on hot dense matter under
the extreme condition
Yu-Gang Ma (???)
(SINAP) Main collaborators Jin-Hui Chen,
Guo-Liang Ma
The 5-th International Conference on Quarks and
Nuclear Physics QNP09, IHEP_at_Beijing, September
21 26, 2009
2
Outline

• Hot dense matter under the extreme condition
• Strange -quark dynamics from ?-meson and W-
  baryon
• s-quark thermalization ? production and W/f
  (PT)
• s-quark collectivity grouping behavior of
  elliptic flow
• s-quark enhancement f-meson enhancement
• s-quark un-polarization f-meson spin
  un-alignment
• s-quark transverse momentum distribution W/f
  (PT/n)
• Constraints on the system evolution dynamics
• Summary/outlook

3
Trigger particle
Hot Dense Matter under the extreme condition
_at_RHIC (1) Away-side peak vanishes in Au-Au
central collision
4 gtpT(assoc) gt 0.15 GeV/c
STAR coll, PRL 95 (2005)152301
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Hot Dense Matter under the extreme condition
(2) Strong suppression of the High pT particles
Nuclear Modification Factor
nucleon-nucleon cross section
ltNbinarygt/sinelpp
AA
If R 1 here, nothing new going on
5
Why f-meson ?
Hot Dense Matter
1 A. Shor, Phys. Rev. Lett. 54 (1985) 1122 2
J. Adams et al., Phys. Lett. B 612 (2005) 181
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The STAR experiment

• Event-mixing method used to estimate
  combinatorial background from uncorrelated KK-
  pairs
• Final subtracted minv distribution fitted with
  Breit-Wigner straight line.

7
?-meson production at RHIC
ltpTgt ?-meson decoupled early
UrQMD

• Evolution in the centrality dependence
• Clear change in spectral shape
• -- Exponential (thermal) for central collisions
• -- Power law type ( hard process) at high pT in
• peripheral collisions

STAR Col. Phys. Lett. B 612, (2005) 181,
Phys. Rev. Lett. 99, (2007) 112301
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f-meson RCP
RCP

• mid-central collisions
• RCP of f meson is more consistent with that of K0
  rather than L, supporting the baryon/meson
  grouping behavior.
• The observable favors the prediction based on
  quark Coal/Recom model (s-sbar?phi).
• peripheral collisions
• The binary scaled f production is very similar to
  that in pp and dAu collisions where strangeness
  production may be canonically suppressed.
• Therefore a baryon-meson scaling behavior of RCP
  is not expected.

SINAP LBL et al. (for STAR), PRL 99 (2007)112301
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Thermalization fs are mostly from bulk
thermal s quarks
SINAP LBL et al. (for STAR), PRL 99
(2007)112301
10
Collectivity of quarks Partonic Collectivity of
multi-strange particles
STAR data (S. Shi et al) PHENIX p and p
nucl-ex/0604011v1 NCQ inspired fit X. Dong et
al. Phy. Let. B 597 (2004) 328
Partonic transport model (AMPT Model)
calculations 1. NCQ scaling works well for
phi/Omega strange quark collectivity 2.
Larger v2 reveals in comparison with AMPT default
and RQMD case. Partonic interaction is essential
to reproduce larger v2 as the data!


J. H. Chen, YGM et al., PRC74, 064902(2006) J.
X. Zuo, J.Y.Chen, X. Cai, YGM, F. Liu et al.,
EPJC 55,463(2008)
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Strangeness enhancement

• We do observe strangeness enhancement yield
  relative to pp
• BUT ?-meson enhancement
• -- Enhancement between net Strangeness 1 (L, K)
  and 2 (X) particles
• -- 200 GeV data gt 62.4 GeV
• The above observations clearly suggest that, at
  these collision energies, the source of
  enhancement of strange hadrons is related to the
  formation of a dense partonic medium in high
• energy nucleusnucleus collisions and cannot be
  alone due to canonical suppression of their
  production
• in smaller systems.

SINAP LBL et al. (for STAR), PLB 673 (2009)183
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Global orbital angular momentum
Huge orbital angular momentum of the collisions
system may lead to global quark polarization of
the system
Z.T. Liang (Shandong), X.N. Wang et al., PRL
94, 102301(2005) PLB 629, 20 (2005)
arXiv0710.2943nucl-th.
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What happen in Experiment?
Lambda un-polarization PLlt0.02 Voloshin et al
(STAR Col.) PRC 76, 024915 (2007)
J.H. Chen (SINAP), Z. Tang (USTC), I.
Selyuzhenkov (STAR), PRC77, 061902(R) (2008)
Un-polarization signal of s-quark might imply
that the system created at RHIC is isotropic to
the extent that, locally, there is no longer a
preferred direction. It favors the QGP scenario.
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Strange quark PT distributions at Hadronization
SINAP, PRC 78 (2008)034907
Can we extract the strange quark pT distribution
from multi-strange hadron data? If baryons at
pT are mostly formed from coalescence of partons
at pT/3 and mesons at pT are mostly formed from
coalescence of partons at pT/2, then we could
extract quark PT information

• and f particles have no decay feed-down
  contribution!
• These particles will freeze-out earlier from the
  system and
• have small hadronic rescattering cross sections.

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Strange and light quark distribution
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s/d quark ratio from primordial hyperon

• s/d ratio from hyperon X0(1530)
  feed-down1 46-14

1 R. Witt, J. Phys. G 34, S921 (2007)
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s/d ratio compared with Reco. model calculation
? Good agreement with the data? Large exp.
uncertainty

• Quark Reco. model predicted a consistent shape
  between s/d ratio and the hyperon ratio.

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Fit parameter of constituent quark mass
Can we put constrains on the constitute quark
mass parameter ?
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Constraints on the system evolution dynamics

• Theoretical model for particle production at
  RHIC typically involve initial conditions,
  partonic evolutions, hadronization and hadronic
  evolutions.
• Theoretical uncertainties due to
  hadronization scheme and hadronic evolution are
  major issues for quantitative description of
  properties of QCD medium created at RHIC.
• eg., the hadronic evolution process have
  been added to the hydrodynamic models as an
  afterburner and have been shown to significantly
  alter the spectra shapes of ordinary hadrons1.
  1 T. Hirano et al., Phys. Rev.
  C 77, 044909 (2008)

Can our derived quark distributions, representing
a cumulative effect from initial conditions
through partonic evolution, be used to determine
the final-state hadron momentum distribution?
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Dynamical model calculation (1)

• A Multi-Phase Transport model1
• Initial condition HIJING
• Partonic evolution ZPC
• Hadronization coalescence
• Hadronic evolution ART

1 Z.W. Lin et al., Phys. Rev. C 72, 064901
(2005)
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Dynamical model calculation (2)

• Modified version
• Tuned the initial parton pT distribution
  inherited from HIJING string melting empirically,
  (vT0,Tth0)
• Requirement the tuned distributions after
  parton cascade match our derived s/d quark dis
• Coalescence scheme two nearest (in coordinate
  space) quarks ? meson while three nearest quarks
  ? baryon.

?An essential ingredient in Reco./Coa. model
calculation the distribution of effective
constituent quarks that readily turn into hadron.
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Summary

• N(f)/N(K) vs. Npart rules out the KK-
  coalescence as a dominant channel for f
  production at RHIC
• N(W)/N(f) vs. pT favors the model prediction
  that fs are made via thermalied s-quarks
  coalescence at RHIC
• N(W)/N(f) and N(X)/N(f) vs. pT/nq indicate the
  s-quark and d-quark have a similar KET
  distribution partons have undergone a partonic
  evolution possibly described by hydrodynamics
  the distribution of effective constituent quarks
  can reproduce the reasonable hyperon Pt
  distribution.
• v2(f) vs. pT concludes that the partonic
  collectivity has been formed at RHIC
• Un-polarization signal of s-quark might imply
  that the system created at RHIC is isotropic to
  the extent that, locally, there is no longer a
  preferred direction. Again, favors the QGP
  scenario.

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All 120 TOF trays are installed at STAR and data
will be taken in next RHIC runs
PID information for gt 95 of kaons and protons
in the STAR acceptance Clean e ID down to 0.2
GeV/c
STAR-China Collaboration plan 120 trays of MRPC
modules which leverage MRPC development at
CERN (Crispin Williams et al)
Development of HPTDC Chip STAR-MRPC TOFs are
contributed from the China-STAR group Fully
complete in time for run 10 (fall 2009)? Phi
reconstruction from ee-

• ?/K separation to 1.6 GeV/c
• 0.7 for TPC alone
• (?K)/p to p 3 GeV/c
• 1.2 for TPC alone
• Clean electron ID down
• to 0.2 GeV

TOFTPC one kaon from f identified by TPC, the
other by TOF TPCTPC the 2 kaons from f
identified using only TPC
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RHIC low energy scan the breaking of NCQ scaling
of elliptic flow?
J. Tian, J. H. Chen, Y. G. Ma et. al., Phys. Rev.
C 79, 067901 (2009)

• Violation of the NCQ scaling for the
  identified-particle elliptic flow may indicate
  the hadronic dominant phase is coming.

Y.G.Ma
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Di-hadron correlation in the AMPT model
Black trigged by ? orO Blue trigged by any
hadron
YGM, JPG 32(2006)S373, SQM06

• Away side Phi/Omega-trigged correlation
  functions are narrower than the hadrons-trigged
  correlation function
• it is consistent with the scenario of earlier
  freeze-out of phi/omega production

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• Many Thanks for STAR
• collaborators, especially for
• Jinhui Chen, Guoliang Ma, Xiangzhou Cai,
• Huanzhong Huang, Nu Xu et al.

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Creation of the Hot Dense Matter under the
extreme condition at RHIC heavy ion collisions
Away-side peak vanishes in Au-Au central
collision_at_200GeV/c ? dense matter
Strong suppression of the High Pt meson ?Hot
dense matter
RHIC creates hot and dense matter, parton loss
energy when traverse the medium.
RHIC white paper Nucl. Phys. A 757