Observation of associated production of a Z boson with a D meson in the forward region

Abstract

A search for associated production of a Z boson with an open charm meson is presented using a data sample, corresponding to an integrated luminosity of 1.0 fb−1 of proton-proton collisions at a centre-of-mass energy of 7TeV, collected by the LHCb experiment. Seven candidate events for associated production of a Z boson with a D0 meson and four candidate events for a Z boson with a D+ meson are observed with a combined significance of 5.1 standard deviations. The production cross-sections in the forward region are measured to be

$ \begin{array}{*{20}{c}} {{\upsigma_{{\mathrm{Z}\to {\upmu^{+}}}}}{{{_{{{\upmu^{-}}}}}}_{{,{{\mathrm{D}}^0}}}}=2.50\pm 1.12\pm 0.22\ \mathrm{pb}} \\ {{\upsigma_{{\mathrm{Z}\to {\upmu^{+}}}}}{{{_{{{\upmu^{-}}}}}}_{{,{{\mathrm{D}}^{+}}}}}=0.44\pm 0.23\pm 0.03\ \mathrm{pb},} \\ \end{array} $

where the first uncertainty is statistical and the second systematic.

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