Searching for a leptophobic B boson through η → π⁰γγ and ηʹ → π⁰γγ decays

¹ Grup de Física Teòrica, Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain
² Institut de Física d’Altes Energies (IFAE) and The Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra (Barcelona), Spain
³ Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA

^* e-mail: rescriba@ifae.es
^** e-mail: sergig@lanl.gov
^*** e-mail: eroyo@ifae.es

Published online: 22 December 2022

Abstract

The sensitivity of the decays η → π⁰γγ and ηʹ → π⁰γγ to a leptophobic B boson in the sub-GeV mass range is summarised in this work. By adding an explicit B-boson resonance exchange to the dominant Standard Model contribution from vector meson exchanges, and employing experimental measurements of the associated branching ratios, the current constraints on the B-boson mass m_B and coupling to Standard Model particles α_B are significantly improved. From these constraints and the analysis of the available experimental γγ invariant mass distribution of η → π⁰γγ, we conclude that a B-boson signature in the resonant mass range m_π⁰ ≲ m_B ≲ m_η is strongly suppressed and would be very difficult to experimentally identified. The η΄ → π⁰γγ decay is not as powerful as the η → π⁰γγ at constraining B-boson parameters below m_η but allow exploring larger B-boson masses. Yet, the task of identifying a B-boson with m_B ∼ m_ω would be very challenging.