The first observation of a new meson state decaying into Bc+ and a photon is presented using a dataset of pp collisions at a center-of-mass energy root s = 13 TeV collected by the ATLAS detector at the Large Hadron Collider, corresponding to an integrated luminosity of 140 fb-1. The Bc+ mesons are reconstructed from a three-muon final state from Bc+ -> J/psi (mu+ mu-) mu+ nu_mu X decays, along with photons reconstructed via conversions to electron-positron pairs in the detector material. The new state is observed with a significance that exceeds 8 standard deviations. The mass difference between the new meson state and the ground-state Bc+ meson is measured to be 64.5 +- 1.4(stat) +1.0-1.4 (syst) MeV. This corresponds to a mass for the observed state of 6339.0 +- 1.4(stat) +1.0-1.4(syst) +- 0.3(m_Bc+) MeV, where the last uncertainty is due to the precision of the best knowledge of the Bc+ meson mass. The low mass difference value matches the theory expectations for the lowest vector state of the bbar c system, the Bc*+ meson.

Aad, G., Aakvaag, E., Abbott, B., Abdelhameed, S., Abeling, K., Abicht, N. ., et al. (2026). Observation of a Bc*+ Meson with the ATLAS Detector. PHYSICAL REVIEW LETTERS, 137(14) [10.1103/vrxp-zkbs].

Observation of a Bc*+ Meson with the ATLAS Detector

Aielli, G.;Camarri, P.;Cerrito, L.;De Sanctis, U.;Di Ciaccio, A.;
2026-01-01

Abstract

The first observation of a new meson state decaying into Bc+ and a photon is presented using a dataset of pp collisions at a center-of-mass energy root s = 13 TeV collected by the ATLAS detector at the Large Hadron Collider, corresponding to an integrated luminosity of 140 fb-1. The Bc+ mesons are reconstructed from a three-muon final state from Bc+ -> J/psi (mu+ mu-) mu+ nu_mu X decays, along with photons reconstructed via conversions to electron-positron pairs in the detector material. The new state is observed with a significance that exceeds 8 standard deviations. The mass difference between the new meson state and the ground-state Bc+ meson is measured to be 64.5 +- 1.4(stat) +1.0-1.4 (syst) MeV. This corresponds to a mass for the observed state of 6339.0 +- 1.4(stat) +1.0-1.4(syst) +- 0.3(m_Bc+) MeV, where the last uncertainty is due to the precision of the best knowledge of the Bc+ meson mass. The low mass difference value matches the theory expectations for the lowest vector state of the bbar c system, the Bc*+ meson.
2026
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Rilevanza internazionale
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Esperti anonimi
Settore PHYS-01/A - Fisica sperimentale delle interazioni fondamentali e applicazioni
English
Con Impact Factor ISI
Aad, G., Aakvaag, E., Abbott, B., Abdelhameed, S., Abeling, K., Abicht, N. ., et al. (2026). Observation of a Bc*+ Meson with the ATLAS Detector. PHYSICAL REVIEW LETTERS, 137(14) [10.1103/vrxp-zkbs].
Aad, G; Aakvaag, E; Abbott, B; Abdelhameed, S; Abeling, K; Abicht, N ; Abidi, S ; Aboelela, M; Aboulhorma, A; Abramowicz, H; Acharya, B ; Ackermann, A...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/474545
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