Preprint
Long-lived Axion-Like Particles from Tau Decays
ArXiv.org
Cornell University
07/21/2025
DOI: 10.48550/arxiv.2507.15271
Abstract
Axion-like particles (ALPs) are well-motivated examples of light, weakly coupled particles in theories beyond the Standard Model. In this work, we study long-lived ALPs coupled exclusively to
leptons in the mass range between 2me and mτ − me. For anarchic flavor structure the leptophilic ALP production in tau decays or from ALP-tau bremsstrahlung is enhanced thanks to derivative couplings of the ALP and can surpass production from electron and muon channels, especially for ALPs heavier than mμ. Using past data from high-energy fixed-target experiments such as CHARM and BEBC we place new constraints on the ALP decay constant fa, reaching scales as high as O(108) GeV in lepton-flavor-violating channels and fa ∼ O(102) GeV in lepton-flavor-conserving ones. We also present projections for the event-rate sensitivity of current and future detectors to ALPs produced at the Fermilab Main Injector, the CERN SPS, and in the forward direction of the LHC. We show that SHiP will be sensitive to fa values that are over an order of magnitude above the existing constraints.
Details
- Title: Subtitle
- Long-lived Axion-Like Particles from Tau Decays
- Creators
- Yohei EmaPatrick J FoxMatheus HostertTony MenzoMaxim PospelovAnupam RayJure Zupan
- Resource Type
- Preprint
- Publication Details
- ArXiv.org
- DOI
- 10.48550/arxiv.2507.15271
- ISSN
- 2331-8422
- Publisher
- Cornell University; Ithaca, New York
- Language
- English
- Date posted
- 07/21/2025
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984946622602771
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