Novel method for identifying the heaviest QED atom

2023/04/29 by Jing-Hang Fu, Sen Jia, Xing-Yu Zhou +4 · 1 voice · 3 citations
Physics and Astronomy · #Dark Matter and Cosmic Phenomena #Neutrino Physics Research #Particle physics theoretical and experimental studies #hep-ex #hep-ph

paper · pdf · doi:10.1016/j.scib.2024.04.003

openalex publication_date 2024/04/05 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

The bound state of a τ⁺τ^- pair by the electromagnetic force is the heaviest and smallest QED atom. Since the discovery of the two lightest QED atoms more than 60 years ago, no evidence for the third one has been found. We demonstrate that the J_τ (τ⁺τ^- atom with J^PC=1^--) resonance signal can be observed with a significance larger than 5σ including both statistical and systematic uncertainties, via the process e⁺e^-→ X⁺ Y^- \slashedE (X, Y=e, μ, π, K, or ρ, and \slashedE is the missing energy) with 1.5~\rm ab^-1 data taken around the τ pair production threshold. The τ lepton mass can be measured in a precision of 2 keV with the same data sample. This is within one year's running time of the proposed super tau-charm factory or super charm-tau factory.

Citations

• The precision Monte Carlo event generator for two-fermion final states in collisions
• Discovering true tauonium via two-photon fusion at e⁺e^- and hadron colliders

Cited by

• Automated event generation for S-wave quarkonium and leptonium production in NRQCD and NRQED
• On Recent measurements of Toponium Threshold Enhancement in Entire-Function-Regulated Nonlocal Quantum Field Theory
• Probing Yoctosecond Quantum Dynamics in Toponium Formation at Colliders

Discussions

• Lepton pairs, often a particle and its antiparticle, form QED atoms. The heaviest is Tauonium, with a radius of 30.4 fm or 1741x smaller than a hydrogen atom. Future colliders are needed to find it as [bsky, 12 points, 0 comments]

Related

• Observation of τ lepton pair production in ultraperipheral nucleus-nucleus collisions with the CMS experiment and the first limits on (g-2)_τ at the LHC
• Discovering true tauonium via two-photon fusion at e⁺e^- and hadron colliders
• Light Quark Masses from Exclusive Tau Decays: An Experimental Proposal
• Probing the electromagnetic dipole moment of the τ lepton in the e⁺e^- → γ^*/Z → τ⁺ τ^- reaction
• Measurement of the mass of the τ-lepton and an upper limit on the mass difference between τ⁺ and τ^-