Y.G.Ma Strangeness Quark Matter (2006), UCLA, March 24-31 1 φ -meson production and partonic collectivity at RHIC Outline Motivation of studying φ-meson

Y.G.Ma Strangeness Quark Matter (2006), UCLA, March 24-31 1

φ-meson production and partonic collectivity at RHIC

OutlineMotivation of studying φ-mesonφ production and elliptic flow from RHICElliptic flow of φ and Ω in AMPTφ/ Ω -trigged di-hadron correlation in AMPTSummary and conclusionOutlook

Yu-Gang Ma

Shanghai Institute of Applied Physics (SINAP), CHINA

Thanks to: X.Z. Cai, J.H. Chen, G.L. Ma, S. Zhang, C. Zhong, J.X. Zuo (SINAP) S. Blyth, N. Xu (LBL), J. G. Ma, H.Z. Huang (UCLA), H.B. Zhang et al.


Flow of strange hadrons

(GeV)

freeze-out of strange hadrons- at higher temperature Tfo - with lower collective velocity T

small cross section of strange hadrons with non-strange hadronssensitivity to the early, partonic stage


Importance of

is a true signal from the early stage of the collision! measurements of will conclude:

Matter status of the system at an early stage partonic vs. hadronic?

origin of observed scaling at intermediate pT mass vs. particle type?

•Rescattering models (RQMD& UrQMD) which predict 2/3 phi come from kaon coalescence shows the increasing behaviors of N(phi)/N(k) and <Pt> from peripheral to central collision.

•Data effectively ruled out that Kaon coalescence as a dominant channel for production at these energies.

STAR: Phys. Rev. C65, 041901(R) (2002)Phys. Lett. B612, 181 (2005)


Production of @ STAR


Freeze-out earlier before radial flow is completely

built up?


Ratios of to π- or K-

1. Phi yields increase faster than pi- in higher sqrt(Snn) onset of strange quark degree of the freedom?

AA>pp: partonic environment favors phi production?2. No strong centrality dependence of phi/K- in Au-Au collisions; RQMD predicts increasing phi/k- vs Npart, and much smaller than the data, Partonic interactions must play improtant role in phi production!


Discrepancy between STAR and PHENIX?

X.Cai QM05, D.Pal QM05S. Blyth, JH Chen et al.

STAR Preliminary


1.The integral yield from STAR is a factor of 100% higher than the PHENIX’s?

Discrepancy between STAR and PHENIX?

J.Rafelski etc. PRC 72 024905

2.No! (Rafelski)


ee vs. KK mass line-shapes

( ee) = 8.9 ± 12.3 MeV/c2

A. Kozlov

dn/dy for ee tends to be larger than for KK

( KK) = 4.22 ± 0.09+0.506 MeV/c2

m( KK) =1.02891 ± 0.00003(stat) ± 0.00085 (syst) GeV/c2

V.Greene, QM05


RCP and RAA

X. Cai, QM05S. Blyth,SQM06

D.Pal QM05

RCP or RAA of φ definitely follows the mesons The observed grouping behavior of RCP /RAA is a kind of meson/baryon effect but not mass effect

STAR Preliminary by J. H. Chen & S. Blyth et al.


STAR Preliminary

Early time informationv2 vs. pT

The φ experiences significant elliptic flow!

Early time information:● For p

T<2 GeV/c, φ flows as much as

other ID'd particles, consistent with hydro. mass-ordering

● For pT>2 GeV/c, φ v

2 is more

consistent with K0S than Λ (favors

NCQ=2)● Consistent with v

2 of other multi-

strange hadrons (Ξ, Ω) i.e. s-quarks flow!

Particle production mechanisms:● Further evidence of species-type

dependence of v2 at intermediate p

T

(described by recombination/ coalescence models)

S. Blyth, J. H. Chen et al., STAR analysis


AMPT model

(1) Default AMPT (2) Melt AMPT

A Multi-Phase Transport model, Ko & Lin et al.


Reconstructed φin AMPT

1.The mass width of Breit-Wigner shape has been set as 4.43MeV

T.Sjostrand,arXiv:hep-ph/95083912.Raw-yield per (pT,φ-ψ2) has been extracted by event-mixing method

3.v2obs ~ { }2 21 2 ( ) cos[2( )]TNorm v p φ ψ× + × −


v2 vs pTD.Pal QM05(PHENIX)

1.Hydrodynamic behavior in AMPT (pT<1.5GeV/c), stronger v2 vs. data, 10mb partonic interaction cross section.

2.Consistent with experimental result (pT>1.5GeV/c).

JH Chen& S. Blyth, STRA preliminary; AMPT: JH Chen et al., Nucl-th/0504055


Centrality dependence of v2 Re-scattering effect in AMPT

Significant v2 has been observed in different centralities

1.Hardon-cascade can be turn on/off to investigate the re-scattering effect.2.Re-scattering effect is small: the pressure becomes more isotropic in later hadronic matter. φ interacts weaker in the hadronic matter.


ABOUT OMEGA V2 in AMPT

1.NCQ scaling looks work even for Omega within error bar. stronger v2 of strange quark: phi & omega.2. Larger v2 reveals in comparison with AMPT default and RQMD case. Partonic effect needs to produce the large v2 as the data! J. Zuo et al., preliminary AMPT results

RQMD: Y. Lu et al., nucl-th/0602009


Soft Associated particles on Away side (thermalization)Soft Associated particles on Away side (thermalization)

near sidenear side

away side

thermalization???thermalization???

<pT > from away jets

<pT> from medium decay

SOFTENED

SOFTENED

What happens to a hard probe that traverses a colored medium?

soften + broaden =?= thermalizationthermalization

BROADENEDBROADENED


correlations from AMPTcorrelations from AMPT ((3<pT

trigger<6GeV/c , 0.15<pTassoc<3GeV/c)

(1) ▲melting AMPT (with later hadron rescattering )

(2) ● melting AMPT (without later hadron rescattering)

(3)◆ Default AMPT (with hadron rescattering)

(4) ★ Default AMPT (without hadron rescattering)

(5) ■ Star preliminary Data

0-5% (4-6)*(0.15-4) GeV/c factor=1.58

-1 0 1 2 3 4 5

0

1

2

3

4

5

6

7

8

AMPT 0-10%,(3-6) x (0.15-3)GeV/c melting version (with hadron cascade) melting version (without hadron cascade) default version (with hadron cascade) default version (without hadron cascade) Star Data 0-5% (4-6) x (0.15-4)GeV/c factor=1.58

1/Ntrig

dN/d

φ

φ(rad)

Au+Au @200GeV/c (0-10%)

G.L. Ma, S. Zhang, YGM et al., nucl-th/0601012


Di-hadron correlation: Black: trigged by Black: trigged by or orΩΩ; ; Blue: Blue: trigged by any hadrontrigged by any hadron

Away side: Phi-trigged correlation narrower than any-hadron trigged correlation consistent with the scenario of earlier freeze-out of phi production?

A good probe to explore strange partonic stage?

Preliminary AMPT results


Special identified associated particle

0 200 400 600 800 1000 12000.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

π K p Λ

bayon/mesonnear: 0.241away: 0.283

Au+Au 200GeV (0-10%)Melt AMPT after hadron cascadespecial associated particle

(2.5-4)X(1-3.0) GeV/cnear sideaway side

associated N

h

m0 (MeV)0 1 2 3

0.0

0.2

0.4

0.6

0.8

1.0

1.2

(2.5-4.0)X(1.0-3.0) GeV/c Melt AMPT 0-10%after hadron cascadespecial associated particle

πkaonprotonΛ

1/Ntrig

dNhadron

/dφ

φ(Rad)

Preliminary AMPT results

Consistent with the hydro mass ordering of v2 for soft particles:Azimuthal distribution -> azimuthal correlation;

Phi/omega trigged correl will be added

YGMa, WQShen, PRC51(1995)3256

2 = 1/2v22


Nucleonic number scaling of V2 in low energy ! (Kr+Ni peripheral, IQMD)

It is interesting to check p, d, t, alpha v2,v4 @ RHIC!

T.Z. Yan, YGM et al, Nucleonic number scaling of V2!


Summary and conclusion

Strong suppression of high Pt power-law tail ofφ has been observed in central collisions from RHIC, the spectra can be fitted well by exponential form ( thermalization). Observed grouping of RCP/RAA at RHIC is a kind of particle type effect but not mass effect. Strange quark DOF ~ u,d quarks Elliptic flow of φ and Ω from AMPT with string melting scenario is consistent with the STAR-Preliminary result: φ and Ω follows NCQ scaling as other hadrons, which indicates the partonic collectivity has been formed at RHIC. Significant φ v2 has been observed in different centralities. Only hadronic stage cannot produce enough large v2-> partonic interaction is needed; Hadronic re-scattering effect on v2 of φ is neglectble effect in AMPT model. AMPT simulations shows that / Ω -trigged di-hadron correlations have narrow away-side Mach-cone or single peaks than all hadron-trigged Δ correlation consistent with the earlier freeze-out of strange quarks! Experimental analysis is waiting.


outlook (1)

STAR analysis: Vector-meson (phi) spin alignment in Au+Au (global ploari

zed QGP?). Ideals: Recombination of q-qbar in polarized QGP; recombination of q(qbar)

in polarized QGP with unpolarized qbar(q); fragmentation from polarized q(qbar)

see: Liang, Wang, PRL 94(05)102301; PLB629(05)20; EXCHARM Coll, PLB 485 (00) 334


Outlook (2)

STAR analysis: /Ω -trigged hadron correlations Narrowing of Mach-like peak or away-side peak by /Ω -trigger

-1 0 1 2 3 4 5

0

1

2

3

AMPT melt before ART

trig particle is φ or Ω trig is any particle(3.0-10)X(0.15-3.0)GeV/c (3.0-6.0)X(0.15-3.0)GeV/c central 40-90% central 40-80%

1/Ntrig

/dN d

φ

φ(rad)

-1 0 1 2 3 4 5

0

1

2

3

4

5

6

AMPT melt before ART central 10-20%

trig particle is φ or Ω trig is any particle(3.0-10)X(0.15-3.0)GeV/c (3.0-6.0)X(0.15-3.0)GeV/c

1/Ntrig

/dN d

φ

φ(rad)

How about the data?


Outlook (3): Φ puzzle? With Full TOF

Full TOF MRPC modules construction has been approved by NSF of China. NSFC, CAS and MoST of China will jointly support the project. It will be finished in 2.5 years.

φ reconstruction with Full TOF: φ -> K+K-

Φ -> e+e-

Φ -> +-

is there a phi puzzle in RHIC energies, esp. in lower Pt region as Model shows?S. Blyth SQM06;Z. Xu, SQM06 (TOF e, )

Open symbols: Φ -> +-Solid symbols: φ -> K+K-Pal, Ko, Lin, NPA707(02)505

NA50

NA49


Outlook (4)

K+K- azimuthal correlation (different minv) vs v2

Low pt: out of Minv region: K v2> v2 K+K- correlation > v2 ; inside Minv region: K+K-

correlation phi v2 ;Middle Pt: K+K- correlation (K v2)

v2 Is it ture in data?


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Y.G.Ma Strangeness Quark Matter (2006), UCLA, March 24-31 1 φ -meson production and partonic collectivity at RHIC Outline Motivation of studying φ-meson