It is shown that the nuclear modification factor can be smaller that unity
for jet production at small x and at large transverse momentum without any
violation of the factorization theorem and the initial state effects is able to
explain the nuclear modification factor of the order of the one measured by
ATLAS. In other word, initial state effects are able to describe the jet
quenching for the gluon jet production.Comment: 6 pp. and 8 figures in .eps file