  A study of color coherence effects in pp collisions at a center-of-mass
energy of 7 TeV is presented. The data used in the analysis were collected in
2010 with the CMS detector at the LHC and correspond to an integrated
luminosity of 36 inverse picobarns. Events are selected that contain at least
three jets and where the two jets with the largest transverse momentum exhibit
a back-to-back topology. The measured angular correlation between the second-
and third-leading jet is shown to be sensitive to color coherence effects, and
is compared to the predictions of Monte Carlo models with various
implementations of color coherence. None of the models describe the data
satisfactorily.
