Are elliptic flow ( v2 ) measurements consistent with the formation of the Quark Gluon Plasma at RHIC ?

1
(No Transcript)
2
Compressed Baryonic Matter at the AGS
A Review !!
Roy A. Lacey (SUNY Stony Brook)
3
The AGS
4
Disclaimer

• A Diverse Range of Experimental Programs have
  been Carried out at the AGS
• AGS Expts.
• E802/866
• E810/891
• E814/877
• E864
• E895
• E917

pA, SiA, AuA 2 18 AGeV 1986 - 14.6
AGeV/c Si 1992 11.0 AGeV/c Au
5
Outline

• Motivation
• Results Implications
• Global Observables
• Rapidity Distributions Stopping
• HBT
• Flow
• Particle Production
• Summary

6
Motivation
7
Motivation High Density Nuclear Matter
Various competing forms of matter are predicted
at high Baryon density
8
Motivation

• Why Study Heavy Ion Reactions at the AGS ?

9
Global Observables
Barette et al., E877
Nc 450 for central collisions
Substantial Pseudorapidity Densities are achieved
10
Energy Density
time to thermalize the system (t0 1 fm/c)
6.5 fm
Barette et al., E877
11
Rapidity Distributions and Baryon Stopping
Holzman et. al E917
Significant Stopping is achieved in central
collisions at the AGS
12
Rapidity Distributions and Baryon Stopping
Braun-Munzinger et al.
Si Al
Au Au
J. Klay et al. E895
13
Radial Flow
Particle Spectra are compatible with significant
radial Flow.
14
HBT
QTO
QL
QTS
C2 is measured as,
Probability to detect 2 particles at p1 and p2,
In the Longitudinal CMS, where (p1p2)beam 0,
15
HBT
Stachel et al.
16
HBT Reaction plane Dependence
Rout lt Rside Initial Overlap gt
Shape at freeze-out
17
Flow
Low Energy Squeeze-out
High Energy In-plane
Pressure Gradients Drive Transverse and Elliptic
flow
18
Danielewicz et al.
V2 is sensitive to the EOS
19
Danielewicz et al.
V2 is sensitive to the Phase Transition
20
Flow
21
Good Agreement with theory, Softening of EOS
22
Differential Flow
Differential Measurements (E895)
23
d1
d2

• Differential Elliptic Flow Studies Provide
  Important Additional Insights on the EOS

24
Sahu et al.
H. Liu E895
Good Agreement with calculation which assumes p
dependent meanfield
25
Flow
Danielewicz et al.
New constraints for the EOS achieved
26
Flow of Produced Particles

• Clear Evidence for in-medium potential

27
Particle Production

• OF Particular Interest
• Enhancement in Strangeness Production
• Enhancement in the ratio Antihyperon/Antibaryon
• ? Probes for the QGP

28
Particle Production
Yields Increase from Peripheral to Central
Collisions -- Consistent With Multiple Collisions
per participant
29
Particle Production
pp
Ratio increases with beam energy possible maximum
Smooth Decrease in enhancement
30
Particle Production
Ratio Increase from Peripheral to Central
Collisions -- Reasonable agreement with model
calculations
31
Particle Production
Braun-Munzinger et al.
Remarkable Agreement with Predictions of Thermal
model
32
Stachel et al.
33
Summary

• Compressed Baryonic Matter is Produced With
  Significant Energy Density at the AGS.
• The study of this matter has provided a wealth of
  insights
• Further Studies are Required for a more complete
  understanding as well as further mapping of the
  phase diagram
• .

34
New constraints for the EOS achieved
35
Motivation Strange Particles

• K- K0 ? attractive Interaction
• K K0 ? Repulsive Interaction
• -? Consequences for Flow
• In QGP
• Production in hadronic gas
• ? pairs of strange hadrons with increased
  threshold
• ? Strangeness Enhancement

The Production and Propagation of Strange Hadrons
constitutes an Important Probe