Cold Nuclear Matter effects in Upsilon production in dAu collisions at RHIC

Understand

We report on our recent study of Cold Nuclear Matter effects on the Upsilon production at RHIC in dAu collisions.

• The first experimental results available on the nuclear modification factor R_dAu have rather large uncertainties.
• They nevertheless allow to bring qualitative information on the nature of the nuclear effects at play on top of the usual nuclear absorption, since the latter is expected to lie in a quite small range around a value close to ten times smaller as for charmonia.
• At backward rapidities, the behavior of R_dAu hints at the presence of a gluon EMC effect, analogous to the quark EMC effect -- but possibly stronger.