The study of a wide peaking structure in the (Formula Presented) mass spectrum is reported using a data sample of proton-proton collisions collected by the LHCb detector at center-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb-1. The observed structure is consistent with the lowest excited P-wave B+c states and exhibits a statistical significance exceeding 7 standard deviations relative to the background-only hypothesis. A two-peak model serves as an effective description of the data, with various theory-constrained models further explored to provide physical interpretation. Based on the predictions for the Bc(1P)+ spectrum, the relative production cross section of the overall Bc(1P)+ states with respect to the (Formula Presented) ground state with the transverse momentum pT and rapidity y of (Formula Presented) mesons in the regions pT < 20 GeV/c and 2.0 < y < 4.5 at (Formula Presented) is measured to be 0.20 \pm 0.03 \pm 0.02 \pm 0.03, where the uncertainty terms represent statistical, systematic, and uncertainties related to the choice of theoretical models, respectively. The results provide a test of theoretical models and deepen our understanding of quantum chromodynamics.

Study of Bc(1P)+ states in the (Formula Presented) mass spectrum

Kleijne N.
Membro del Collaboration Group
;
Morello M. J.
Membro del Collaboration Group
;
Passaro D.
Membro del Collaboration Group
;
Pica L.
Membro del Collaboration Group
;
Riccardi D.
Membro del Collaboration Group
;
Xu A.
Membro del Collaboration Group
;
2025

Abstract

The study of a wide peaking structure in the (Formula Presented) mass spectrum is reported using a data sample of proton-proton collisions collected by the LHCb detector at center-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb-1. The observed structure is consistent with the lowest excited P-wave B+c states and exhibits a statistical significance exceeding 7 standard deviations relative to the background-only hypothesis. A two-peak model serves as an effective description of the data, with various theory-constrained models further explored to provide physical interpretation. Based on the predictions for the Bc(1P)+ spectrum, the relative production cross section of the overall Bc(1P)+ states with respect to the (Formula Presented) ground state with the transverse momentum pT and rapidity y of (Formula Presented) mesons in the regions pT < 20 GeV/c and 2.0 < y < 4.5 at (Formula Presented) is measured to be 0.20 \pm 0.03 \pm 0.02 \pm 0.03, where the uncertainty terms represent statistical, systematic, and uncertainties related to the choice of theoretical models, respectively. The results provide a test of theoretical models and deepen our understanding of quantum chromodynamics.
2025
Settore FIS/01 - Fisica Sperimentale
Settore PHYS-01/A - Fisica sperimentale delle interazioni fondamentali e applicazioni
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11384/167783
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