Observation of an Excited Bc⁺ state

Using p p collision data corresponding to an integrated luminosity of 8.5     fb − 1 recorded by the LHCb experiment at center-of-mass energies of √ s = 7 , 8, and 13 TeV, the observation of an excited B + c state in the B + c π + π − invariant-mass spectrum is reported. The observed peak has a mass of 6841.2 ± 0.6 ( stat ) ± 0.1 ( syst ) ± 0.8 ( B + c )     MeV / c 2 , where the last uncertainty is due to the limited knowledge of the B + c mass. It is consistent with expectations of the B ∗ c ( 2 3 S 1 ) + state reconstructed without the low-energy photon from the B ∗ c ( 1 3 S 1 ) + → B + c γ decay following B ∗ c ( 2 3 S 1 ) + → B ∗ c ( 1 3 S 1 ) + π + π − . A second state is seen with a global (local) statistical significance of 2.2 σ ( 3.2 σ ) and a mass of 6872.1 ± 1.3 ( stat ) ± 0.1 ( syst ) ± 0.8 ( B + c )     MeV / c 2 , and is consistent with the B c ( 2 1 S 0 ) + state. These mass measurements are the most precise to date

Observation of an Excited B-c(+) State

Using $pp$ collision data corresponding to an integrated luminosity of $8.5\,\mathrm{fb}^{-1}$ recorded by the LHCb experiment at centre-of-mass energies of $\sqrt{s} = 7$, $8$ and $13\mathrm{\,Te\kern -0.1em V}$, the observation of an excited $B_c^+$ state in the $B_c^+\pi^+\pi^-$ invariant-mass spectrum is reported. The observed peak has a mass of $6841.2 \pm 0.6 {\,\rm (stat)\,} \pm 0.1 {\,\rm (syst)\,} \pm 0.8\,(B_c^+) \mathrm{\,MeV}/c^2$, where the last uncertainty is due to the limited knowledge of the $B_c^+$ mass. It is consistent with expectations of the $B_c^{*}(2^{3}S_{1})^+$ state reconstructed without the low-energy photon from the $B_c^{*}(1^{3}S_{1})^+ \to B_c^+ \gamma$ decay following $B_c^{*}(2^{3}S_{1})^+ \to B_c^{*}(1^{3}S_{1})^+ \pi^+ \pi^-$. A second state is seen with a global (local) statistical significance of $2.2\,\sigma$ ($3.2\,\sigma$) and a mass of $6872.1 \pm 1.3 {\,\rm (stat)\,} \pm 0.1 {\,\rm (syst)\,} \pm 0.8\,(B_c^+) \mathrm{\,MeV}/c^2$, and is consistent with the $B_c(2^{1}S_{0})^+$ state. These mass measurements are the most precise to date.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2019-007.htm

Observation of an Excited B_c^+ State

Using pp collision data corresponding to an integrated luminosity of 8.5  fb^-1 recorded by the LHCb experiment at center-of-mass energies of sqrt[s]=7, 8, and 13 TeV, the observation of an excited B_c^+ state in the B_c^+π^+π^- invariant-mass spectrum is reported. The observed peak has a mass of 6841.2±0.6(stat)±0.1(syst)±0.8(B_c^+)  MeV/c^2, where the last uncertainty is due to the limited knowledge of the B_c^+ mass. It is consistent with expectations of the B_c^*(2^3S_1)^+ state reconstructed without the low-energy photon from the B_c^*(1^3S_1)^+→B_c^+γ decay following B_c^*(2^3S_1)^+→B_c^*(1^3S_1)^+π^+π^-. A second state is seen with a global (local) statistical significance of 2.2σ (3.2σ) and a mass of 6872.1±1.3(stat)±0.1(syst)±0.8(B_c^+)  MeV/c^2, and is consistent with the B_c(2^1S_0)^+ state. These mass measurements are the most precise to date