Energy loss of fast quarks in nuclei.
We report an analysis of the nuclear dependence of the yield of Drell-Yan dimuons from the 800 GeV/c proton bombardment of 2H, C, Ca, Fe, and W targets. Employing a new formulation of the Drell-Yan process in the rest frame of the nucleus, this analysis examines the effect of initial-state energy loss and shadowing on the nuclear-dependence ratios versus the incident proton's momentum fraction and dimuon effective mass. The resulting energy loss per unit path length is -dE/dz = 2.32+/-0.52+/-0.5 GeV/fm. This is the first observation of a nonzero energy loss of partons traveling in a nuclear environment.
Johnson
M B
MB
Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Kopeliovich
B Z
BZ
Potashnikova
I K
IK
McGaughey
P L
PL
Moss
J M
JM
Peng
J C
JC
Garvey
G T
GT
Leitch
M J
MJ
Adams
M R
MR
Alde
D M
DM
Baer
H W
HW
Barlett
M L
ML
Brown
C N
CN
Cooper
W E
WE
Carey
T A
TA
Danner
G
G
Hoffmann
G W
GW
Hsiung
Y B
YB
Kaplan
D M
DM
Klein
A
A
Lee
C
C
Lillberg
J W
JW
McCarthy
R L
RL
Mishra
C S
CS
Wang
M J
MJ