1110.5047 (E. G. Ferreiro et al.)

Gluon EMC effect and fractional energy loss in Upsilon production in dAu
collisions at RHIC    [PDF]

E. G. Ferreiro, F. Fleuret, J. P. Lansberg, N. Matagne, A. Rakotozafindrabe

We argue that the Upsilon nuclear modification factor, R^Upsilon_dAu, measured at RHIC can only be reproduced once gluon EMC effect and fractional energy loss are taken into account. At backward rapidities, the visible suppression of R^Upsilon_dAu hints at the presence of a gluon EMC effect, analogous to the quark EMC effect -- but likely stronger. At forward and mid rapidities, the data can only be accounted for by a fractional energy loss, recently revived in the literature. Our conclusions do not depend on the detail of the nuclear parton distributions. Such a fractional energy loss also provides an alternative explanation to gluon saturation for the strong forward J/psi suppression in dAu collisions observed by PHENIX.

View original: http://arxiv.org/abs/1110.5047