Measurement of the $\tau$ lepton mass with the Belle II experiment

Abstract We present a measurement of the $\tau$-lepton mass using a sample of about 175 million $e^+e^- \to \tau^+\tau^-$ events collected with the Belle II detector at the SuperKEKB $e^+e^-$ collider at a center-of-mass energy of $10.579\,\mathrm{Ge\kern -0.1em V}$. This sample corresponds to an integrated luminosity of $190\,\mathrm{fb^{-1}}$. We use the kinematic edge of the $\tau $ pseudomass distribution in the decay ${\tau^-\to\pi^-\pi^+\pi^-\nu_\tau}$ and measure the $\tau$ mass to be $1777.09 \pm 0.08 \pm 0.11 \,\mathrm{Me\kern -0.1em V\!/c^2}$, where the first uncertainty is statistical and the second systematic. This result is the most precise to date.
Tags
Working group Tau
Principal authors @  Eduard Cruz Burelo, Michel Hernandez Villanueva, Navid Rad, Armine Rostomyan, Radek Zlebcik
Reference Phys.Rev.D 108, 032006 (2023), DOI: 10.1103/PhysRevD.108.032006
Document BELLE2-PUB-PH-2023-021
Links arXiv:2305.19116, Inspire, PRD
Bibtex 
@article{Belle-II:2023izd,
    author = "Adachi, I. and others",
    collaboration = "Belle-II",
    title = "{Measurement of the {\ensuremath{\tau}}-lepton mass with the Belle II experiment}",
    eprint = "2305.19116",
    archivePrefix = "arXiv",
    primaryClass = "hep-ex",
    reportNumber = "Belle II Preprint 2023-008, KEK Preprint 2023-6",
    doi = "10.1103/PhysRevD.108.032006",
    journal = "Phys. Rev. D",
    volume = "108",
    number = "3",
    pages = "032006",
    year = "2023"
}