2021/08/25 by Kingman Cheung, A. Soffer, Abner Soffer +3
Chemistry · Physics and Astronomy · #Axion #Branching fraction #Chemistry #Combinatorics #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Dark matter #Electron #Flavor #Graph #Lepton #Monte Carlo method #Neutrino Physics Research #Nuclear physics #Particle physics #Particle physics theoretical and experimental studies #Physics #Statistics #Vertex (graph theory) #hep-ex #hep-ph
paper · pdf · doi:10.1007/jhep11(2021)218
v1, 27 pages, 9 figures, 3 tables; v2, minor changes, mainly updated beam-dump and lepton-flavor-universality constraints, accepted for publication in JHEP
openalex publication_date 2021/11/01 · arxiv created 2021/11/19 · arxiv updated 2021/12/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
A bstract We study charged lepton flavor violation associated with a light leptophilic axion-like particle (ALP), X , at the B -factory experiment Belle II. We focus on production of the ALP in the tau decays τ → Xl with l = e, μ , followed by its decay via X → l − l + . The ALP can be either promptly decaying or long-lived. We perform Monte-Carlo simulations, recasting a prompt search at Belle for lepton-flavor-violating τ decays, and propose a displaced-vertex (DV) search. For both types of searches, we derive the Belle II sensitivity reaches in both the product of branching fractions and the ALP coupling constants, as functions of the ALP mass and lifetime. The results show that the DV search exceeds the sensitivity reach of the prompt search to the relevant branching fractions by up to about a factor of 40 in the long decay length regime.