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 $ σZ→μ+μ−,D0=2.50±1.12±0.22 pbσZ→μ+μ−,D+=0.44±0.23±0.03 pb, $

where the first uncertainty is statistical and the second systematic.