First Observation of the Decay B+c→J/ψπ+π−π+

Abstract

The decay B + c → J / ψ π + π − π + is observed for the first time, using 0.8 fb − 1 of p p collisions at √ s = 7 TeV collected by the LHCb experiment. The ratio of branching fractions B ( B + c → J / ψ π + π − π + ) / B ( B + c → J / ψ π + ) is measured to be 2.41 ± 0.30 ± 0.33 , where the first uncertainty is statistical and the second is systematic. The result is in agreement with theoretical predictions.