Nuclear modification factor for identified hadrons at forward rapidity in Au Au reactions at 200GeV

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Nuclear modification factor for identified
hadrons at forward rapidity in AuAu reactions at
200GeV

• Radoslaw Karabowicz
• for the BRAHMS Collaboration
• Marian Smoluchowski Institute of Physics,
• Jagiellonian University, Kraków, Poland

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BRAHMS experiment

• Data analyzed
• AuAu, pp at sqrt(s_NN)200GeV

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RICH Pid
m2 GeV2/c4
r cm
RICH Pid 3 sigma cut. In the overlapping
regions Pid based on statistical weighting of
Gaussian distibution in r.
p GeV/c
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y-pT map coverage
Different colors different angle and field
settings

• trigger normalization
• acceptance
• tracking efficiency
• Pid efficiency

AuAu 200 AGeV pions
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pT spectra
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RCP in AuAu _at_ 200 AGeV
(d2NAuAu/dpTdy)/ltNcollgt0-10
RCP
(d2NAuAu/dpTdy)/ltNcollgt40-50
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RAA in AuAu _at_ 200 AGeV
1 d2NAuAu/dpTdy
RAA
ltNcollgt d2Nppinel/dpTdy
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Increase of ratios with decreasing
centrality Pions and kaons ratios flat Protons
show Cronin peak at pt2
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RAA comparison with RCP
RCP and RAA are consistent for pions and kaons
For protons RCP shows suppression, while RAA
shows enhancement
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RAA at y0 and y3.1
RAA for pions at forward rapidities agrees with
RAA at midrapidity
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RCP at y0 and y3.1
RCP for pions at forward rapidities copies the
behaviour of RCP at midrapidity
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RCP at y0 and y3.0
For protons however data at forward rapidity show
significant suppression in RCP
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RdAu compared with RAA
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SUMMARY

• identified particle yields has been measured by
  BRAHMS at forward rapidity for AuAu and pp
  collisions
• RAA shows significant suppression for pions and
  kaons, but for protons it shows enhancement
• RCP and RAA are consistent for pions and kaons,
  but deviate for protons
• no difference in pion RAA between midrapidity
  (PHENIX p0) and forward rapidity (BRAHMS pp-/2)
  consistent with surface jet-emission
• baryons RCP shows suppression at forward
  rapidities in contrast with midrapidity
• pions RAA shows stronger suppression as compared
  to RdAu

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The BRAHMS Collaboration
I.Arsene11, I.G. Bearden6, D. Beavis1,
S.Bekele10, C. Besliu9, B. Budick5, H. Bøggild6 ,
C. Chasman1, C. H. Christensen6, P.
Christiansen6, R.Clarke9, R.Debbe1, J. J.
Gaardhøje6, K. Hagel7, H. Ito1, A. Jipa9, J. I.
Jordre9, F. Jundt2, E.B.Johnson10, J.I.Jordre8,
C.Jørgensen6, R. Karabowicz3, E. J. Kim10,
T.M.Larsen6, J. H. Lee1, Y. K.Lee4, S.Lindal11,
G. Løvhøjden2, Z. Majka3, M. Murray10, J.
Natowitz7, B.S.Nielsen6, D.Ouerdane6,
R.Planeta3, F. Rami2, C.Ristea6, O.Ristea9, D.
Röhrich8, B. H. Samset11, S. J. Sanders10,
R.A.Sheetz1, P. Staszel3, T.S. Tveter11,
F.Videbæk1, R. Wada7, H.Yang8, Z. Yin8, and I.
S. Zgura9 1Brookhaven National Laboratory, USA,
2IReS and Université Louis Pasteur, Strasbourg,
France 3Jagiellonian University, Cracow, Poland,
4Johns Hopkins University, Baltimore, USA, 5New
York University, USA 6Niels Bohr Institute,
University of Copenhagen, Denmark 7Texas AM
University, College Station. USA, 8University of
Bergen, Norway 9University of Bucharest,
Romania, 10University of Kansas, Lawrence,USA
11 University of Oslo Norway 48 physicists
from 11 institutions
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