STAR Patricia Fachini 1 Brookhaven National Laboratory Motivation Data Analysis Results Conclusions...

14
Patricia Fachini 1 STAR Patricia Fachini Brookhaven National Laboratory Motivation Data Analysis Results Conclusions Resonance Production in Au+Au and p+p Collisions at s NN =200 GeV
  • date post

    19-Dec-2015
  • Category

    Documents

  • view

    215
  • download

    2

Transcript of STAR Patricia Fachini 1 Brookhaven National Laboratory Motivation Data Analysis Results Conclusions...

Page 1: STAR Patricia Fachini 1 Brookhaven National Laboratory Motivation Data Analysis Results Conclusions Resonance Production in Au+Au and p+p Collisions at.

Patricia Fachini 1STAR

Patricia FachiniBrookhaven National

LaboratoryMotivation

Data AnalysisResults

Conclusions

Resonance Production in Au+Au and p+p Collisions at sNN=200 GeV

Page 2: STAR Patricia Fachini 1 Brookhaven National Laboratory Motivation Data Analysis Results Conclusions Resonance Production in Au+Au and p+p Collisions at.

Patricia Fachini 2STAR

Motivation - I • In-medium modification of mass and/or width Chiral Symmetry

Restoration, Collision Broadening or Phase Space?

• ρ0(770) Leptonic decay channel probes all stages of the collision. Hadronic decay channel probes only late stages of the collision

• Φ Information from early time ? • f0(980) KK molecule (bound state) insight strangeness

behavior in relativistic collisions• K*0(892) Regeneration and daughter rescattering time scale ?

ρ0 ρ0π-

π+

π+

π-

ρ0 c = 1.3 fm

ρ0

ρ0

+

+

-

-

π- π+

ρ0

-

+

Φ c = 44 fm

Page 3: STAR Patricia Fachini 1 Brookhaven National Laboratory Motivation Data Analysis Results Conclusions Resonance Production in Au+Au and p+p Collisions at.

Patricia Fachini 3STAR

Motivation - II • If resonance decays before

kinetic freeze-out not reconstructed due to rescattering of daughters

• K*0 (c = 4 fm) survival probability time between chemical and kinetic freeze-out, source size and pT of K*0

• Chemical freeze-out elastic interactions πK K*0 πK regenerate K*0(892) until kinetic freeze-out

• K*0/K may reveal time between chemical and thermal freeze-out

• Λ*/Λ, ρ0/π, f0/π ?

Chemical freeze-out

Kinetic freeze-out

K*

lost

K*

measuredπ

π

K

K*K

K*

K*

π

K

ππK*

K K K*

measured

Page 4: STAR Patricia Fachini 1 Brookhaven National Laboratory Motivation Data Analysis Results Conclusions Resonance Production in Au+Au and p+p Collisions at.

Patricia Fachini 4STAR

0(770) π+ π- B.R. ~1 c = 1.3 fm

K*0(892) π K B.R. 2/3 c = 4 fm

f0(980) π+ π- B.R. 2/3 c = 2.6 fm

Φ(1020) K+ K- B.R. 0.492 c = 44 fm

Φ(1020) e+ e- B.R. 0.000296 c = 44 fm

Λ(1520) p K B.R. 0.45 c = 12.6 fm

• |y| ≤ 0.5

• Mixed Event or Like Sign Technique

Resonance Production at RHIC

Page 5: STAR Patricia Fachini 1 Brookhaven National Laboratory Motivation Data Analysis Results Conclusions Resonance Production in Au+Au and p+p Collisions at.

Patricia Fachini 5STAR

Raw Invariant Mass Distribution from Data P. Fachini, L. Gaudichet, J. Ma, C. Maguire, H. Zhang SQM2003

Invariant Mass (GeV/c2) Invariant Mass (GeV/c2) Invariant Mass (GeV/c2) Invariant Mass (GeV/c2)

p+p

p+p Au+Au

Au+Au Au+Au

STAR Preliminary

STAR Preliminary

STAR Preliminary

PHENIX Preliminary PHENIX Preliminary

K*0

Φ

Φ

ΦK+K- Φe+e-

Statistical error only

J. Adams et al. nucl-exp/0307023

STAR

p+p 40%-80% Au+Au

J. Adams et al. nucl-exp/0307023

STAR

K*0

STAR Preliminary

|y|<0.5

sNN = 200 GeV

Au+Au

STAR Preliminary

Λ(1520)

p+p 60%-80% Au+AuSTAR Preliminary

Λ(1520)

Page 6: STAR Patricia Fachini 1 Brookhaven National Laboratory Motivation Data Analysis Results Conclusions Resonance Production in Au+Au and p+p Collisions at.

Patricia Fachini 6STAR

K*0 Mass and Width

• K*0 mass shifted in p+p and Au+Au at low pT

• K*0 width agrees with the MC (GEANT) calculation• Systematic and statistical error added in quadrature

H. Zhang, SQM2003

STAR PreliminarySTAR Preliminary

|y|<0.5

sNN = 200 GeV

Page 7: STAR Patricia Fachini 1 Brookhaven National Laboratory Motivation Data Analysis Results Conclusions Resonance Production in Au+Au and p+p Collisions at.

Patricia Fachini 7STAR

Phase Space

P. Braun-Munzinger et.al., CERES Int. Note, March 2000, unpublished; E.V. Shuryak and G.E. Brown, Nucl. Phys. A 717 (2003) 322; P.K. Kolb and M. Prakash, nucl-th/0301007; H.W. Barz et al., Phys. Lett. B 265, 219 (1991); R. Rapp, hep-ph/0305011.

ρ0

π-

π+

π-

π+

• M = Invariant Mass; pT = transverse momentum; T = Temperature

• pp particle composition reasonably reproduced by statistical model T = 160 MeV

F. Becattini, Nucl. Phys. A 702, 336 (2002); Z. Phys. C 69, 485 (1996); F. Becattini and U. Heinz, Z. Phys. C 76, 269 (1997)

• Au+Au between chemical and kinetic freeze-out resonances formed until particles too far apart resonances emitted T = 120 MeV

E.V. Shuryak and G.E. Brown, Nucl. Phys. A 717 (2003) 322

e- M2 + pT

2

TM

M2 + pT2

Phase Space =

BW(M) = Γ(M)

(M2 – M2)2 + M

2 Γ(M)2

Γ(M) = Γρ

M2 – 4mπ2

Mρ2 – 4mπ

2

32 Mρ

M

Page 8: STAR Patricia Fachini 1 Brookhaven National Laboratory Motivation Data Analysis Results Conclusions Resonance Production in Au+Au and p+p Collisions at.

Patricia Fachini 8STAR

ρ0 Mass J. Adams et al. nucl-exp/0307023

• p+p at s = 27.5 GeV M = 762.6 ± 2.6 MeV/c2

• PDG average hadroproduced ρ0

M = 769.0 ± 0.9 MeV/c2

• PDG average e+e- ρ M = 775.9 ± 0.5 MeV/c2

• ρ0 mass pt dependent and lower than previous p+p measurement in both p+p and peripheral Au+Au collisions

• ρ0 mass high multiplicity p+p lower than minimum bias p+p multiplicity dependent

• Systematic errors common and correlated between p+p and peripheral Au+Au

• ρ0 width no sensitivity for systematic study

10% of minimum bias p+p for |η|<0.5

|y|<0.5

sNN = 200 GeV

Page 9: STAR Patricia Fachini 1 Brookhaven National Laboratory Motivation Data Analysis Results Conclusions Resonance Production in Au+Au and p+p Collisions at.

Patricia Fachini 9STAR

Mass Shift…

• Dynamical Effect E.V. Shuryak and G.E. Brown, Nucl. Phys. A 717 (2003) 322; R. Rapp, hep-ph/0305011.

– ρ0 interactions at late stages of the collision• nucleons, hyperons and baryon resonances• pions, kaons and ρ0-mesons• t-channel exchanges

Distortion of the ρ0 spectral shape mass shift and/or broadening

• Interference between various π+π- scattering channels R. Longacre, nucl-exp/0305015

• Bose-Einstein correlations between ρ0 decay daughters and pions in the surrounding matter G.D. Lafferty, Z. Phys. C 60, 659 (1993); R. Rapp, hep-ph/0305011; S. Pratt et al., nucl-th/0308087.

-23 MeV/c2 shift in the ρ0 mass

-38 MeV/c2 shift in the ρ0 mass due to t-channel attraction

Page 10: STAR Patricia Fachini 1 Brookhaven National Laboratory Motivation Data Analysis Results Conclusions Resonance Production in Au+Au and p+p Collisions at.

Patricia Fachini 10STAR

Spectra

• Au+Au spectra fit to exponential in mT-m0

• p+p spectra fit to power-law contribution pQCD processes larger than soft processes ?

P. Fachini, SQM2003 J. Adams et al. nucl-exp/0307023

L. Gaudichet, SQM2003

STAR Preliminary

Λ(1520)

pp

ρ0

f0

Φ

J. Ma, SQM2003

STAR Preliminary

H. Zhang, SQM2003

K*0

STAR Preliminary

Statistical error only

STAR Preliminary

sNN = 200 GeV|y|<0.5

Page 11: STAR Patricia Fachini 1 Brookhaven National Laboratory Motivation Data Analysis Results Conclusions Resonance Production in Au+Au and p+p Collisions at.

Patricia Fachini 11STAR

• Φ/K- independent of centrality Φ not produced via kaon coalescence ?

• Cross-section regeneration or rescattering ?

M. Bleicher et al. J. Phys. G 25 (1999) 1859

Particle Ratios

STAR Preliminary

J. Adams et al. nucl-exp/0307023 H. Zhang SQM2003L. Gaudichet,

SQM2003 J. Ma SQM2003

P. Fachini SQM2003

Statistical and systematic errors added in quadrature

Page 12: STAR Patricia Fachini 1 Brookhaven National Laboratory Motivation Data Analysis Results Conclusions Resonance Production in Au+Au and p+p Collisions at.

Patricia Fachini 12STAR

• Φ and K*0 No centrality dependence• Φ Flows differently ?• K*0 Rescattering dominates at peripheral collisions and

regeneration becomes significant for central collisions ?

H. Zhang, SQM2003 J. Ma, SQM2003 H. Zhang, SQM2003 J. Ma, SQM2003

STAR Preliminary

STAR Preliminary

<pT> Charged Particle DependenceStatistical and systematic errors added in quadrature

Page 13: STAR Patricia Fachini 1 Brookhaven National Laboratory Motivation Data Analysis Results Conclusions Resonance Production in Au+Au and p+p Collisions at.

Patricia Fachini 13STAR

Thermal Models

• Short-lived resonances Kinetic freeze-out ?

Chemical freeze-out

Kinetic freeze-out

Chemical = kineticfreeze-out

mρ=700MeV

mρ=770MeV

f0

π-

ρ0

π-

K*0

K-

ΦK-

Λ(1520)Λ

Statistical and systematic errors added in quadrature

sNN = 200 GeV

Page 14: STAR Patricia Fachini 1 Brookhaven National Laboratory Motivation Data Analysis Results Conclusions Resonance Production in Au+Au and p+p Collisions at.

Patricia Fachini 14STAR

• Significant resonance production measured from hadronic interactions from RHIC data at sNN = 200 GeV

• ρ0 and K*0 mass shift observed even after phase space correction in p+p and Au+Au collisions

• Lower mass expected due to in-medium modifications, interference and Bose-Einstein correlations ?

• Φ/K- independent of centrality Φ not produced via kaon coalescence ?

• Short-lived resonances Regeneration and rescattering driven by hadronic cross sections ?

• Resonances can provide information on the collision dynamics

Conclusions