forward and high pt physics at rhic with brahms
DESCRIPTION
Forward and high pt physics at RHIC with BRAHMS. Stopping in Au+Au at √s=200, 62.4 GeV Rapidity dependence of high pt suppression of hadrons at √s=200 GeV Au+Au and d+Au at η =0 Au+Au at η =2.2, 3.2 d+Au at η = 0 to 3.2 (CGC?) - PowerPoint PPT PresentationTRANSCRIPT
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 1
Forward and high pt physics at RHIC with BRAHMS
Stopping in Au+Au at √s=200, 62.4 GeV
Rapidity dependence of high pt suppression of hadrons at √s=200 GeV
Au+Au and d+Au at η=0 Au+Au at η=2.2, 3.2 d+Au at η= 0 to 3.2 (CGC?)
Energy dependence of high pt suppression of hadrons at √s=62.4 GeV
in Au+Au at η= 0, 1
Flavor dependence in Au+Au and d+Au
Rapidity dependence of particle production in p+p collisions
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 2
The BRAHMS experiment
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 3
Excellent Hadron Identification by TOF and RICH
m2=p2( t2 / L2 -1)
D
p
KD
FS 4 deg
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 4
Transparency and beam energy loss at RHIC
BRAHMS PRL 93 (2004) 102301
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 5
Net Protons at 62.4 GeV
BRAHMS preliminary
0-5%
y
dN(p-pbar)/dy
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 6
Rapidity and energy loss at RHIC
Rapidity loss saturates!
But Energy loss increases strongly
dE(baryon)=75GeV
ΔE(tot)=26TeV
Out of available
35 TeV
Relative rapidity loss :
35% < y/yb < 44%
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 7
Total relativistic energy
Produced particles
in -3<y<+3
carry about
9 TeV of total energy
E = mt cosh(y)
mt=(pt2+m2)1/2
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 8
pt21
RAA
0
The smoking gun of QGP? Jet Quenching, high pt suppression.
ddp/d/N
ddp/NdR
TNN2NN
inelbin
T2
AA
Soft Hard (jets)
BRAHMS: PRL 91 (2003) 072305
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 9
Test: Absence of suppression at midrapidity in d+Au?
q
q
AuD
PRL 91 (2003) 072305
1/5
Absence of high pt suppression at midrapidity rules out initial
state effects .
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 10
What does theory have to say?
HIJING: pQCD (hard) + strings (soft),shadowing, very schematic jet quenching (1992)
Vitev-Gyulassy: pQCD (hard), no softCronin kT broadening, shadowing and (GLV) jet quenching
Cassing et al: pQCD (hard) + strings (soft)kT broadening, shadowing and energy loss (pre-hadronic and hadronic)
Hirano-Nara: pQCD (hard) + hydro (soft)Cronin kT broadening, shadowing and (GLV) jet quenching
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 11
High pt suppression persists at forward rapidity
Large high pt suppression also at forward rapidity.
Longitudinally extended medium, boost invariance, CGC or …?
Not quantitatively understood.
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 12
Energy loss by stimulated gluon emission in QGP ?
q
q
q
q
QCD: <E> g ln(1/L) dz
<L2>
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 13
RAuAu for hadrons at η=3.2 (4degrees)RHIC run IV
BRAHMS: preliminary
RCP indicates strong high pt suppression at very forward rapidities in
Au+Au
RCP= RdAu (0-20%) / (60-80%)
RdAu (30-50%) / (60-80%)
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 14
RAuAu @ 62.4 GeVη=0 and η=0.95
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 15
No sudden transition…..
√Snn (GeV)
?
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 16
Color Glass CondensateThe fundamental state of the colliding nuclei?
X= p(parton) /p(nucleon)
AuD
Measure at large y on D side:
Probes small x in Au
detector
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 17
Color Glass Condensate in d+Au collisions?
BRAHMS accepted PRL nucl-ex / 0403005
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 18
Centrality dependence … in d+Au
RCP= RdAu (0-20%) / (60-80%)
RdAu (30-50%) / (60-80%)
Most central to peripheral ratio is most enhanced at midrapidity and most suppressed at forward rapidity
This centrality inversion is consistent with the CGC model.
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 19
’High pt’ spectra are different for baryons and mesons in Au+Au
Very different from p+p and e++e-
Hadronic flow or partonic mechanism?
Qualitative agreement with parton recombination models, but need results from run IV for higher pt
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 20
How does it look in d+Au ? Identified hadrons at 4 degrees (η=3.2)
π
K
p
PID with RICH
At eta= 3.2
P-bar : 10%
Π- : 80%
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 21
RdAu at η=3.2(min.bias) Baryon meson difference in d+Au
Strong Difference between
mesons (pions) and Baryons
(anti-p) persists at forward rapidity
in d+Au collisions
BRAHMS preliminary
Flow?
Isospin?
Need to understand
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 22
The hadron spectrum for d+Au at η=3.2
But many protons at forward rapidity
Excess of h+ over h-
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 23
Difference understandable from relative abundances
h+ = 0.8h-( 1 + p/+ + K/+)
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 24
p+p at 200GeVParticle ratios vs rapidity
PYTHIA misses 200GeV protons
BRAHMS, nucl-ex/0409002, Submitted to Phys. Lett. B (2004)
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 25
Proton/pion in p+p at η=3.2vs. Pythia (vs. 6.303)
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 26
Summary
Large high pt suppression at midrapidity in Au+Au. Gluon radiation energy loss?
No suppression in d+Au => no initial state effects. Large effect (factor 5).
Strong high pt suppression in Au+Au persists at forward rapidities- need quantitative understanding.
Reduced high pt suppression in Au+Au at 62.4 GeV
Decrease in R(dAU) from η=0 to η=3.2 and centrality dependence inversion. Consistency with CGC picture.
Baryon/mesons difference sseen at midrapidty in Au+Au is also present in d+Au at forward rapidity.
Pythia does not reproduce protons in p+p.
=== > BRAHMS whitepaper on RHIC discoveries: Nucl-ex/0410020, subm. Nucl. Phys. A
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 27
Extra material
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 28
Is a unified picture emerging?
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 29
New Physics?
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 30
I.G. Bearden7, D. Beavis1, C. Besliu10, Y. Blyakhman6, J. Bondorf7, J.Brzychczyk4, B. Budick6, H. Bøggild7, C. Chasman1, C. H. Christensen7, P. Christiansen7, J.Cibor4, R.Debbe1, J. J. Gaardhøje7, M. Germinario7, K. Grotowski4, K. Hagel8, O.
Hansen7, A. Holm7, A.K. Holme12, H. Ito1, E. Jacobsen7, A. Jipa10, J. I. Jordre9, F. Jundt2, E. Johnson11, C. E. Jørgensen7,T. Keutgen9, E. J. Kim11, T. Kozik3, T.M.Larsen12, J. H. Lee1, Y. K.Lee5, G. Løvhøjden12, Z. Majka3, A. Makeev8, B. McBreen1, M. Murray11, J. Natowitz8, B.S.Nielsen7, K. Olchanski1, D. Ouerdane7, R.Planeta4, F. Rami2, D. Roehrich9, B. H.
Samset12, S. J. Sanders11, D. Sandberg7,I. S. Sgura10, R.A.Sheetz1, Z.Sosin3, P. Staszel7,3, T.S. Tveter12, F.Videbæk1, R. Wada8 and A.Wieloch3.
1Brookhaven National Laboratory, USA 2IReS and Université Louis Pasteur, Strasbourg, France
3Jagiellonian University, Cracow, Poland 4Institute of Nuclear Physics, Cracow, Poland 5Johns Hopkins University, Baltimore, USA
6New York University, USA 7Niels Bohr Institute, Blegdamsvej 17, University of Copenhagen, Denmark 8Texas A&M University, College Station. USA
9University of Bergen, Norway 10University of Bucharest, Romania
11University of Kansas, Lawrence,USA 12 University of Oslo Norway
BRAHMS Intl. collaboration
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 31
At lower energy the opposite is seen :High pt enhancement
CERN- SPS
(snn=17 GeV)
High p_t enhancement seen when compared to p+p scaled by N_binary.
Cronin effect:
quark mult scattering
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 32
p+p reference at 62.4 GeV: a problem
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 33
Transverse spin asymmetry for pions using polarized p+p collisions
STAR PRL 92,06230(2004)D.L.Adams (E704) Phys.Lett B264,462(1991);
Phys.ReV D53, 4747 (1996). FNAL704
AANN = (s+ - s-) / (s+ + s-) = (s+ - s-) / (s+ + s-)
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 34
First results at high XF
<ε >~ -0.035 AN = -0.08 +- 0.005 +- [0.015]
0.17 < xF < 0.32
< ε >~ +0.022 AN = +0.05 +- 0.005 +- [0.015]
0.17 < xF < 0.32
BRAHMS preliminary
AANN = = εε /P P=0.40 - 0.45 /P P=0.40 - 0.45
εε = (N+ /L+ - N-/L-) / (N+ /L+ + N-/L-) = (N+ /L+ - N-/L-) / (N+ /L+ + N-/L-)
= (N+ - L*N-) / (N+ + L*N-) with L = L+ / L-= (N+ - L*N-) / (N+ + L*N-) with L = L+ / L-
π+
November 8 2004
Ericeira Jens Jørgen Gaardhøje, Niels Bohr Institute 35
BRAHMS whitepaperon RHIC discoveries
Conclusion: …There is no doubt that the experiments at RHIC have revealeda plethora of new phenomena that for the most part have come as asurprise. In this sense it is clear that the matter that iscreated at RHIC differs from anything that has been seen before.What name to give it must await our deeper understanding of thismatter.
Nucl-ex/0410020, subm. Nucl. Phys. A