Observation of the B c + → J / ψ π + π 0 $$ {B}_c^{+}\to J/\psi {\pi}^{+}{\pi}^0 $$ decay

Abstract

Abstract The first observation of the B c + → J / ψ π + π 0 $$ {B}_c^{+}\to J/\psi {\pi}^{+}{\pi}^0 $$ decay is reported with high significance using proton-proton collision data, corresponding to an integrated luminosity of 9 fb −1, collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13 TeV. The ratio of its branching fraction relative to the B c + → J / ψ π + $$ {B}_c^{+}\to J/\psi {\pi}^{+} $$ channel is measured to be B B c + → J / ψ π + π 0 B B c + → J / ψ π + = 2.80 ± 0.15 ± 0.11 ± 0.16 , $$ \frac{{\mathcal{B}}_{B_c^{+}\to J/\psi {\pi}^{+}{\pi}^0}}{{\mathcal{B}}_{B_c^{+}\to J/\psi {\pi}^{+}}}=2.80\pm 0.15\pm 0.11\pm 0.16, $$ where the first uncertainty is statistical, the second systematic and the third related to imprecise knowledge of the branching fractions for B + → J/ψK *+ and B c + → J / ψ π + $$ {B}_c^{+}\to J/\psi {\pi}^{+} $$ decays, which are used to determine the π 0 detection efficiency. The π + π 0 mass spectrum is found to be consistent with the dominance of an intermediate ρ + contribution in accordance with a model based on QCD factorisation.

Keywords

• B Physics
• Hadron-Hadron Scattering
• QCD
• Spectroscopy