  We suggest that the combined effect of screening, gluon-induced dissociation,
collisional damping, and reduced feed-down explains most of the sequential
suppression of Upsilon(nS) states that has been observed in PbPb relative to pp
collisions at sqrt(s_NN) = 2.76 TeV. The suppression is thus a clear, albeit
indirect, indication for the presence of a QGP. The Upsilon(1S) ground state
suppression is essentially due to reduced feed-down, collisional damping and
gluodissociation, whereas screening prevails for the suppression of the excited
states.
