Observation of an excited $B_c^{+}$ state

Abstract

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 $13\mathrm{Te}\mathrm{V}$, 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 $6841.2\pm 0.6(\mathrm{stat})\pm 0.1(\mathrm{syst})\pm 0.8(B_c^{+})\mathrm{MeV}/c^2$, where the last uncertainty is due to the limited knowledge of the $B_c^{+}$ mass. It is consistent with expectations of the $B_c^{\ast }(2^3{S}_1{)}^{+}$ state reconstructed without the low-energy photon from the $B_c^{\ast }(1^3{S}_1{)}^{+}\to B_c^{+}\gamma$ decay following $B_c^{\ast }(2^3{S}_1{)}^{+}\to B_c^{\ast }(1^3{S}_1{)}^{+}{\pi }^{+}{\pi }^{-}$. A second state is seen with a global (local) statistical significance of $2.2\sigma$ ($3.2\sigma$) and a mass of $6872.1\pm 1.3(\mathrm{stat})\pm 0.1(\mathrm{syst})\pm 0.8(B_c^{+})\mathrm{MeV}/c^2$, and is consistent with the $B_c(2^1{S}_0{)}^{+}$ state. These mass measurements are the most precise to date.

arXiv commentAll figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2019-007.html

References in corpus (43)

• PYTHIA 6.4 Physics and Manual
• PYTHIA 6.2 Physics and Manual
• Asymptotic formulae for likelihood-based tests of new physics
• LHCb Detector Performance
• PHOTOS Monte Carlo: a precision tool for QED corrections in Z and W decays
• Properties of heavy quarkonia and B_c mesons in the relativistic quark model
• Mesons with Beauty and Charm: Spectroscopy
• Decay Chain Fitting with a Kalman Filter
• Trial factors for the look elsewhere effect in high energy physics
• Observation of the B_c Meson in p-bar p Collisions at sqrt{s} = 1.8 TeV
• Observation of B_c Mesons in p-bar p Collisions at sqrt{s} = 1.8 TeV
• Spectroscopy of B_c Mesons in the Relativized Quark Model
• $B_c$ spectroscopy
• Heavy Mesons In A Relativistic Model
• Mass distributions marginalized over per-event errors
• Precise heavy-light meson masses and hyperfine splittings from lattice QCD including charm quarks in the sea
• Observation of an Excited $B_c^{\pm }$ Meson State with the ATLAS Detector
• Prospects for the Bc Studies at LHCb
• Observation of two excited B${}_{\mathrm{c}}^{+}$ states and measurement of the B${}_{\mathrm{c}}^{+}$(2S) mass in pp collisions at $\sqrt{s}=$ 13 TeV
• Phenomenological prediction of the properties of the B_{C} system
• Measurements of $B_c^{+}$ production and mass with the $B_c^{+}\to J/\psi {\pi }^{+}$ decay
• Observation of $B_c^{+}\to J/\psi D_s^{+}$ and $B_c^{+}\to J/\psi D_s^{\ast +}$ decays
• First observation of the decay Bc+ to J/psi pi+pi-pi+
• First observation of the decay $B_c^{+}\to J/\psi K^{+}$
• Measurement of $B_c^{+}$ production in proton-proton collisions at $\sqrt{s}=8$ TeV
• $B_c$ Spectroscopy from Lattice QCD
• Measurement of b-hadron masses
• Observation of the decay Bc+ -> Bs0 pi+
• Bc spectroscopy in a quantum-chromodynamic potential model
• Observation of the decay $B_c^{+}\to \psi (2S){\pi }^{+}$
• Measurement of the $B_c^{+}$ meson lifetime using $B_c^{+}\to J/\psi {\mu }^{+}{\nu }_{\mu }X$ decays
• Measurement of the lifetime of the $B_c^{+}$ meson using the $B_c^{+}\to J/\psi {\pi }^{+}$ decay mode
• Measurement of the ratio of branching fractions $\mathcal{B}(B_c^{+}\to J/\psi K^{+})/\mathcal{B}(B_c^{+}\to J/\psi {\pi }^{+})$
• Observation of the decay $B_c\to J/\psi K^{+}{K}^{-}{\pi }^{+}$
• First observation of a baryonic $B_c^{+}$ decay
• Observation of $B_c^{+}\to D^0{K}^{+}$ decays
• Measurement of the branching fraction ratio $\mathcal{B}(B_c^{+}\to \psi (2S){\pi }^{+})/\mathcal{B}(B_c^{+}\to J/\psi {\pi }^{+})$
• BCVEGPY2.2: A Newly Upgraded Version for Hadronic Production of the Meson $B_c$ and Its Excited States
• Properties of $B_c$ meson
• Search for excited $B_c^{+}$ states
• Radiative decays of Bc mesons in a Bethe-Salpeter model
• Observation of $B_c^{+}\to J/\psi D^{(\ast )}{K}^{(\ast )}$ decays
• Evidence for the decay $B_c^{+}\to J/\psi 3{\pi }^{+}2{\pi }^{-}$

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• Heavy Flavour Physics and CP Violation at LHCb: a Ten-Year Review
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• Purely leptonic decays of the ground charged vector mesons
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• Next-to-next-to-leading order matching of beauty-charmed meson $B_c$ and $B_c^{\ast }$ decay constants
• Measurement of B${}_{\mathrm{c}}$(2S)${}^{+}$ and B${}_{\mathrm{c}}^{\ast }$(2S)${}^{+}$ cross section ratios in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Excited $B_c$ States via Continuum QCD
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• Weak nonleptonic decays of vector B-mesons
• New parametrization of the form factors in $\bar{B}\to D\ell {\bar{\nu }}_{\ell }$ decays
• Can the hyperfine mass splitting formula in heavy quarkonia be applied to the $B_c$ system?
• Finding $B_c(3S)$ States via Their Strong Decays
• Photonic production of the pair of $B_c$ mesons
• Next-to-leading order QCD corrections to the production of $B_c$ and $B_c^{\ast }$ through $W^{+}$-boson decays
• Exclusive Decays of the Doubly Heavy Baryon ${\Xi }_{bc}$
• The Decay constants of $B_c(nS)$ and $B_c^{\ast }(nS)$
• Photoproduction of the $B_c$ meson at the future $e^{+}{e}^{-}$ colliders
• Searching $B_c^{\ast }$ via conservation laws
• The Radial Excited Heavy Mesons
• Observation of orbitally excited $B_c^{+}$ states
• M1 Radiative and spin-nonflip $\pi \pi$ transitions of $B_c$ states in the Cornell potential model
• $B_c$ to $A$ Transition Form Factors and Semileptonic Decays in Self-consistent Covariant Light-front Approach
• Analysis of the bottom-charm baryon states with QCD sum rules
• Spectroscopy of heavy-heavy flavour mesons and annihilation widths of quarkonia
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• Production of $D$-wave states of $\bar{b}c$ quarkonium at the LHC
• Study of $B_c(1P{)}^{+}$ states in the $B_c^{+}\gamma$ mass spectrum
• Experimental summary: QCD session of the 54th Rencontres de Moriond (Moriond QCD 2019)
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• Heavy flavour production and spectroscopy
• Chromopolarizability of charm-beauty quarkonium from $B_c(2S)\to B_c\pi \pi$ transition
• Study of the two-body nonleptonic $B_c(2S)$ weak decays with the QCD factorization approach