production and suppression in heavy ion collisions at star
DESCRIPTION
Production and Suppression in Heavy Ion Collisions at STAR. February 5, 2013. Anthony Kesich University of California, Davis STAR Collaboration. Outline. Motivation for measuring Upsilons The S olenoidal T racker A t R HIC and its triggers production cross section in p+p - PowerPoint PPT PresentationTRANSCRIPT
Production and Suppression in Heavy Ion Collisions at STAR
Anthony KesichUniversity of California, Davis
STAR Collaboration
February 5, 2013
2
Outline
• Motivation for measuring Upsilons• The Solenoidal Tracker At RHIC and its
triggers• production cross section in p+p• production in d+Au• Nuclear Modification Factor in Au+Au• Suppression Models• Conclusions
February 5, 2013 WWND 2013 - A. Kesich
WWND 2013 - A. Kesich 3
Goal: Quarkonia states in A+ACharmonia: J/Ψ, Ψ’, χc Bottomonia: (1S), (2S), (3S),χB Key Idea: Quarkonia Melt in the plasma
• Color screening of static potential between heavy quarks• Suppression of states is determined by TC and their binding energy• Lattice QCD: Evaluation of spectral functions Tmelting• Originaly proposed by Matsui & Satz (1986)
When do states melt?
February 5, 2013
H. Satz, HP06
A .M
ocsy
, Sum
mer
Qua
rkon
ium
Wor
ksho
p, B
NL,
201
1
WWND 2013 - A. Kesich 4
Quarkonia at RHIC
• A cleaner probe compared to J/Ψ • co-mover absorption → negligible• recombination → negligible
• σcc = ~800 µb• σbb= ~ 2µb
• Challenge: low rate, rare probe– Large acceptance detector– Efficient trigger
February 5, 2013
Why do at RHIC instead of J/Ψ?
R. R
app
et a
l., a
rXiv
:080
7.24
70 [h
ep-p
h]Da
ta fr
om: H
. Per
eira
Da
Cost
a [P
HEN
IX C
olla
bora
tion]
, Nuc
l. Ph
ys. A
774
(200
6) 7
47.
Regeneration of J/ψ!
WWND 2013 - A. Kesich 5
STAR
EM Calorimeter
•|η| < 1•Full φ coverage•Electron ID via E/p•Event Triggering
Time Projection Chamber
•|η| < 1•Full φ coverage•Tracking and EID via Ionization
February 5, 2013
WWND 2013 - A. Kesich 6
Triggering on decays
February 5, 2013
Level 0 Trigger (p+p,d+Au,Au+Au):•Hardware-based•Fires on at least one high tower
Level 2 Trigger (p+p,d+Au):•Software-based•Calculates:• Cluster energies• Opening angle• Mass
High rejection rate allowed us to sample entire luminosity
WWND 2013 - A. Kesich 7
in p+p 200 GeV
February 5, 2013
N(total)= 145±26(stat.)
STAR Preliminary
Phys
. Rev
. D 8
2 (2
010)
120
04
2009, ∫L dt = 19.7 pb-1 2006, ∫L dt = 7.9 pb-1
Statistical error reduced bya factor of 2!
WWND 2013 - A. Kesich 8
in p+p 200 GeV, Comparisons
February 5, 2013
STAR √s=200 GeV p+p ++→e+e- cross section consistent with pQCD and world data trend
STAR Preliminary
CEM
: R. V
ogt,
Phys
. Rep
. 462
125,
200
8CS
M: J
.P. L
ansb
erg
and
S. B
rods
ky, P
RD 8
1, 0
5150
2, 2
010
WWND 2013 - A. Kesich 9
in d+Au 200 GeV
February 5, 2013
∫L dt = 32.6 nb-1
N = 79 ± 17 (stat.) ± 13 (syst.)
Signal has ~8σ significancepT reaches ~8 GeV/c
STAR Preliminary
Efficiency/calibrations under study
WWND 2013 - A. Kesich 10
in Au+Au 200 GeV
February 5, 2013
Raw yield of e+e- with |y|<0.5 = 197 ± 36∫L dt ≈ 1400 µb-1
WWND 2013 - A. Kesich 11
in Au+Au 200 GeV, Centrality
February 5, 2013
Peripheral Central
STAR Preliminary
STAR Preliminary
STAR Preliminary
WWND 2013 - A. Kesich 12
in Au+Au 200 GeV, RAA
February 5, 2013M
odel
s fro
m M
. Stri
ckla
nd a
nd D
. Baz
ow,
arXi
v:11
12.2
761v
4A.
Em
erick
et a
l., E
ur. P
hys.
J. A4
8 (2
012)
72
•Strickland uses a dynamic model with fireball expansion and feed-down• Results are consistent with complete 2S and 3S suppression in
this model• Model is assumes a T0 in the range of 428-442 MeV and 1/4π<
η/S < 3/4π•Emerick & Rapp band covers two scenarios:• Binding energy of the Upsilon decreases with T (Weak Binding)• Suppression is due to gluo-dissociation of Upsilon (Strong
Binding)
WWND 2013 - A. Kesich 13
Outlook
February 5, 2013
Au+Au @ 200 GeV, 2011• Same setup as in 2010• Double the total luminosity
• Approximately 2.8 nb-1
p+p @ 500 GeV, 2011• High energy doubles Upsilon cross section• Excited-to-ground state ratio• PT spectrum• Approximately 22 pb-1 of data
WWND 2013 - A. Kesich 14
Outlook
February 5, 2013
New muon detectors will open up a second, cleaner channelfor Upsilon detection. About 60% of it is currently installed.Important due to increased material in the detector from new vertexer
Statistical Error Projection for Muon Detectors
WWND 2013 - A. Kesich 15
Conclusions
• Measured production in p+p, d+Au, and Au+Au collisions at 200 GeV
• Au+Au results consistent with 2S and 3S suppression
• Increased Au+Au statistics from run 11 will further decrease RAA uncertainties
• New muon channel will enhance and compliment our electron measurementsFebruary 5, 2013
WWND 2013 - A. Kesich 16February 5, 2013
Thank you