A structure is observed in the B± K∓ mass spectrum in a sample of proton–proton collisions at centre-of-mass energies of 7, 8, and 13 TeV, collected with the LHCb detector and corresponding to a total integrated luminosity of 9 fb^−1. The structure is interpreted as the result of overlapping excited B0s states. With high significance, a two-peak hypothesis provides a better description of the data than a single resonance. Under this hypothesis the masses and widths of the two states, assuming they decay directly to B± K∓, are determined to be m_1 = 6063.5 ± 1.2(stat) ± 0.8(syst) MeV, Γ_1 = 26 ± 4(stat) ± 4(syst) MeV, m_2 =6114 ± 3(stat) ± 5(syst) MeV, Γ_2 = 66 ± 18(stat) ± 21(syst) MeV. Alternative values assuming a decay through B*± K∓, with a missing photon from the B*± → B± γ decay, which are shifted by approximately 45 MeV, are also determined. The possibility of a single state decaying in both channels is also considered. The ratio of the total production cross-section times branching fraction of the new states relative to the previously observed Bs2*0 state is determined to be 0.87 ± 0.15(stat) ± 0.19(syst).

Observation of New Excited B0s States

Capriotti, L.;
2021

Abstract

A structure is observed in the B± K∓ mass spectrum in a sample of proton–proton collisions at centre-of-mass energies of 7, 8, and 13 TeV, collected with the LHCb detector and corresponding to a total integrated luminosity of 9 fb^−1. The structure is interpreted as the result of overlapping excited B0s states. With high significance, a two-peak hypothesis provides a better description of the data than a single resonance. Under this hypothesis the masses and widths of the two states, assuming they decay directly to B± K∓, are determined to be m_1 = 6063.5 ± 1.2(stat) ± 0.8(syst) MeV, Γ_1 = 26 ± 4(stat) ± 4(syst) MeV, m_2 =6114 ± 3(stat) ± 5(syst) MeV, Γ_2 = 66 ± 18(stat) ± 21(syst) MeV. Alternative values assuming a decay through B*± K∓, with a missing photon from the B*± → B± γ decay, which are shifted by approximately 45 MeV, are also determined. The possibility of a single state decaying in both channels is also considered. The ratio of the total production cross-section times branching fraction of the new states relative to the previously observed Bs2*0 state is determined to be 0.87 ± 0.15(stat) ± 0.19(syst).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/3582680
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