Signals consistent with the Bc+(2S) and Bc∗+(2S) states are observed in proton-proton collisions at s=13 TeV, in an event sample corresponding to an integrated luminosity of 143 fb-1, collected by the CMS experiment during the 2015-2018 LHC running periods. These excited bc states are observed in the Bc+π+π- invariant mass spectrum, with the ground state Bc+ reconstructed through its decay to J/ψπ+. The two states are reconstructed as two well-resolved peaks, separated in mass by 29.1±1.5(stat)±0.7(syst) MeV. The observation of two peaks, rather than one, is established with a significance exceeding five standard deviations. The mass of the Bc+(2S) meson is measured to be 6871.0±1.2(stat)±0.8(syst)±0.8(Bc+) MeV, where the last term corresponds to the uncertainty in the world-average Bc+ mass.

Sirunyan, A., Tumasyan, A., Adam, W., Ambrogi, F., Bergauer, T., Brandstetter, J., et al. (2019). Observation of Two Excited Bc+ States and Measurement of the Bc+(2S) Mass in pp Collisions at sqrt(s)=13  TeV. PHYSICAL REVIEW LETTERS, 122(13) [10.1103/PhysRevLett.122.132001].

Observation of Two Excited Bc+ States and Measurement of the Bc+(2S) Mass in pp Collisions at sqrt(s)=13  TeV

Benaglia, A.;Beschi, A.;Brivio, F.;Ciriolo, V.;Dinardo, M.  E.;Fiorendi, S.;Ghezzi, A.;Govoni, P.;Malberti, M.;Monti, F.;Moroni, L.;Ortona, G.;Paganoni, M.;Ragazzi, S.;Tabarelli de Fatis, T.;Zuolo, D.;Massironi, A.;Gerosa, R.;Lucchini, M.  T.;De Guio, F.;
2019

Abstract

Signals consistent with the Bc+(2S) and Bc∗+(2S) states are observed in proton-proton collisions at s=13 TeV, in an event sample corresponding to an integrated luminosity of 143 fb-1, collected by the CMS experiment during the 2015-2018 LHC running periods. These excited bc states are observed in the Bc+π+π- invariant mass spectrum, with the ground state Bc+ reconstructed through its decay to J/ψπ+. The two states are reconstructed as two well-resolved peaks, separated in mass by 29.1±1.5(stat)±0.7(syst) MeV. The observation of two peaks, rather than one, is established with a significance exceeding five standard deviations. The mass of the Bc+(2S) meson is measured to be 6871.0±1.2(stat)±0.8(syst)±0.8(Bc+) MeV, where the last term corresponds to the uncertainty in the world-average Bc+ mass.
Articolo in rivista - Articolo scientifico
Physics - LHC - CMS - B Physics
English
2019
122
13
none
Sirunyan, A., Tumasyan, A., Adam, W., Ambrogi, F., Bergauer, T., Brandstetter, J., et al. (2019). Observation of Two Excited Bc+ States and Measurement of the Bc+(2S) Mass in pp Collisions at sqrt(s)=13  TeV. PHYSICAL REVIEW LETTERS, 122(13) [10.1103/PhysRevLett.122.132001].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/224411
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