Related papers: Prospects for $\tau$ Lepton Physics at Belle II

Charged lepton flavor violation is forbidden in the Standard Model but possible in several new physics scenarios. In many of these models, the radiative decays $\tau^{\pm}\rightarrow\ell^{\pm}\gamma$ ($\ell=e,\mu$) are predicted to have a…

Belle~II has unique sensitivity for a broad class of models postulating the existence of dark matter particles with masses in the MeV--GeV range. We present recent world-leading results from Belle~II searches for several non-SM particles.…

Currently the heavy flavour factory KEKB located at the KEK accelerator centre in Tsukuba, Japan, is being upgraded to the Super KEKB factory, aiming for a substantially higher luminosity of 8x10^35 cm^-2 s^-1. This by a factor of 40…

The Belle II detector at the SuperKEKB accelerator observed the first collisions in April this year. Until mid-summer, the first commissioning run uses a reduced version of the full vertex detector. Nevertheless, this phase is an excellent…

An absolute measurement of the $\Lambda^{+}_c$ lifetime is reported using $\Lambda_c^+\rightarrow pK^-\pi^+$ decays in events reconstructed from data collected by the Belle II experiment at the SuperKEKB asymmetric-energy electron-positron…

Within an effective-field-theory framework, we present a model-independent analysis of the potential of discovering new physics by searching for lepton flavour violation in heavy quarkonium decays and, more in general, we study the…

Beyond Standard Model scenarios addressing the flavor puzzle and the hierarchy problem generally predict dominant new physics couplings with fermions of the third generation. In this Letter, we explore the collider and astrophysical…

The Belle II experiment, operating at the asymmetric SuperKEKB $e^+e^-$ collider, is preparing an upgrade of its vertex detector to cope with an increased luminosity of $6 \times 10^{35}$ cm$^{-2}$s$^{-1}$. The upgraded vertex detector…

The future FCC-ee collider is designed to deliver $\mathrm{e^+e^-}$ collisions to study with ultimate precision the Z, W, and Higgs bosons, and the top quark. In a high-statistics scan around the Z pole, $1.3\times 10^{11}$ events…

The HyperCP experiment reported the observation of three events for the $\Sigma^+ \rightarrow p \mu^+\mu^-$ decay. The dimuon masses of the observed events are clustered within the detector resolution of 1 MeV/$c^2$. These decays might be…

The Belle~II experiment is designed to search for physics beyond the Standard Model by investigating rare decays at the SuperKEKB \(e^{+}e^{-}\) collider. Owing to the significant beam background at high luminosity, the data acquisition…

We report on a search for a resonance $X$ decaying to a pair of muons in $e^{+}e^{-}\rightarrow \mu^+ \mu^- X$ events in the 0.212-9.000 GeV/$c^{2}$ mass range, using 178 fb$^{-1}$ of data collected by the BelleII experiment at the…

Decays of $B$ mesons involving the transition of a $b$ quark into an $s$ quark are good probes of physics beyond the standard model. Such decays are studied at the Belle II experiment, a detector located along the SuperKEKB…

We have searched for the lepton-flavor-violating decays tau- -> ell-K0s and ell-K0sK0s (ell = e or mu), using a data sample of 671 fb^-1 collected with the Belle detector at the KEKB asymmetric-energy e^+e^- collider. No evidence for a…

We present a search for the lepton-flavor-violating decays $B^{0} \to \tau^\pm \ell^\mp$, where $\ell=(e,\,\mu)$, using the full data sample of $772 \times 10^6$ $B \overline{B}$ pairs recorded by the Belle detector at the KEKB…

We utilize a sample of 34.6 fb$^{-1}$, collected by the Belle II experiment at the SuperKEKB asymmetric energy $e^+e^-$ collider, to search for the $B^+ \to \phi K^+$, $B^+ \to \phi K^{*+}$, $B^0 \to \phi K^0_S$, and $B^0 \to \phi K^{*0}$…

Beyond $B$ physics, charm and $\tau$ physics constitute a central part of the Belle and Belle II physics programs. Here, we present recent results on charm baryon decays, including first measurements and observations of several previously…

The analyses of states with double $cs$ content and the search for exotics have recently gained much attention. The Belle experiment collected roughly 1 ab$^{-1}$ integrated luminosity data. While Belle II data-taking is in progress, we…

The Belle II physics potential for hadron spectroscopy, inputs to g-2, fragmentation functions, proton form factors, measurements of $\alpha_s$ and hadronic $\tau$ decays is outlined.

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 $\tau \to X l$ with $l=e,\mu$, followed…