Branching fraction ratios between the decays Bs0->J/Psi eta' are measured using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb-1. The measured ratios of these branching fractions are (Formula presented.) where the uncertainties are statistical, systematic and related to the precision of the eta(') branching fractions, respectively. They are used to constrain the eta/eta' mixing angle, phi_P, and to probe the presence of a possible glueball component in the eta' meson, described by the gluonic mixing angle psi_G. The obtained results are (Formula presented.) where the uncertainties are statistically dominated. While the value of phi_P is compatible with existing experimental determinations and theoretical calculations, the angle phi_G differs from zero by more than four standard deviations, which points to a substantial glueball component in the η′ meson and/or unexpectedly large contributions from gluon-mediated processes in these decays. The absolute branching fractions are also measured relative to that of the well-established Bs0->J/Psi phi decay, which serves as the normalisation channel. These results supersede the previous LHCb measurements and are the most precise to date.
Improved measurement of eta/eta' mixing in Bs0->J/Psi eta' decays
Celestino I.Membro del Collaboration Group
;Cordova G.Membro del Collaboration Group
;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
Branching fraction ratios between the decays Bs0->J/Psi eta' are measured using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb-1. The measured ratios of these branching fractions are (Formula presented.) where the uncertainties are statistical, systematic and related to the precision of the eta(') branching fractions, respectively. They are used to constrain the eta/eta' mixing angle, phi_P, and to probe the presence of a possible glueball component in the eta' meson, described by the gluonic mixing angle psi_G. The obtained results are (Formula presented.) where the uncertainties are statistically dominated. While the value of phi_P is compatible with existing experimental determinations and theoretical calculations, the angle phi_G differs from zero by more than four standard deviations, which points to a substantial glueball component in the η′ meson and/or unexpectedly large contributions from gluon-mediated processes in these decays. The absolute branching fractions are also measured relative to that of the well-established Bs0->J/Psi phi decay, which serves as the normalisation channel. These results supersede the previous LHCb measurements and are the most precise to date.| File | Dimensione | Formato | |
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JHEP10(2025)113.pdf
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