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Abstract :
Rapidity distributions are presented for events containing either a Z boson
or a photon with a single jet in proton-proton collisions produced at the CERN
LHC. The data, collected with the CMS detector at sqrt(s) = 7 TeV, correspond
to an integrated luminosity of 5.0 inverse femtobarns. The individual rapidity
distributions of the boson and the jet are consistent within 5% with
expectations from perturbative QCD. However, QCD predictions for the sum and
the difference in rapidities of the two final-state objects show discrepancies
with CMS data. In particular, next-to-leading-order QCD calculations, and two
common Monte Carlo event generators using different methods to match
matrix-element partons with parton showers, appear inconsistent with the data
as well as with each other.
