Related papers: Snowmass White Paper: Belle II physics reach and p…

We propose a new method to probe the magnetic and electric dipole moments of the $\tau$ lepton using precise measurements of the differential rates of radiative leptonic $\tau$ decays at high-luminosity $B$ factories. Possible deviations of…

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 $B^0 \to \phi K^{*0}$…

The Belle and Belle~II experiments have accumulated a data set of $1.2~\mathrm{ab}^{-1}$ of $e^+e^- \to B\bar{B}$ collisions at the $\Upsilon(4S)$ resonance. Owing to the clean event environment and well-constrained initial-state…

The semileptonic $B$ meson decays of the type $B \to X_u \ell \nu$ are important for measuring the magnitude of the CKM matrix element $V_{ub}$. Recent measurements of inclusive $B \to X_u e \nu_e$ and hadronically tagged $B^0 \to \pi^-…

Recently, the Belle II collaboration announced the first measurement of $\mathcal B(B^+\to K^+\nu\bar\nu)$, which is found to be about $2.7\sigma$ higher than the SM prediction. We decipher the data with two new physics scenarios: the…

This document presents a selection of QCD studies accessible to high-precision studies with hadronic final states in $e^+e^-$ collisions at Belle II. The exceptionally clean environment and the state-of-the-art capabilities of the Belle~II…

We report the recent results of a search for lepton-flavor-violating tau decays and a search for CP violation in tau to nu Ks pi using a large data sample accumulated with the Belle detector at the KEKB asymmetric-energy e^+e^- collider.…

The Belle II experiment at the Super B factory SuperKEKB, an asymmetric $e^+e^-$ collider located in Tsukuba, Japan, is tailored to perform precision B physics measurements. The centre of mass energy of the collisions is equal to the rest…

We report a measurement of the branching fraction of $B \to K^{\ast}(892)\ell^+\ell^-$ decays, where $\ell^+\ell^- = \mu^+\mu^-$ or $e^+e^-$, using electron-positron collisions recorded at an energy at or near the $\Upsilon(4S)$ mass and…

Semileptonic ${B}$ meson decays involving low-mass charged leptons ${e}$ or ${\mu}$ are expected to be free of non-Standard Model contributions and therefore play a critical role in determinations of ${\vert V_{ub} \vert}$ and ${\vert…

The Belle II experiment at the SuperKEKB energy-asymmetric $e^+e^-$ collider is a substantial upgrade of the B factory facility at KEK in Tsukuba, Japan. It aims to record a factor of 50 times more data than its predecessor. The experiment…

The large number of $\tau$ leptons available at the Belle II experiment makes it possible to study their properties and the extent of their compositeness. Our strategy relies on three observables defined in terms of elements of the…

We report the measurements of various hadronic $B$ decays at the Belle II experiment using a $362 fb^{-1}$ sample of electron-positron collisions collected at the $\Upsilon(4S)$ resonance. All results agree with the previous determination,…

The Belle detector at the KEKB electron-positron collider has collected almost 1 billion Y(4S) events in its decade of operation. Super-KEKB, an upgrade of KEKB is under construction, to increase the luminosity by two orders of magnitude…

The Belle II experiment is a high-energy physics experiment at the SuperKEKB electron-positron collider. Using Belle II data, high precision measurement of rare decays and CP-violation in heavy quarks and leptons can be performed to probe…

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…

We measure the photon-energy spectrum in radiative bottom-meson ($B$) decays into inclusive final states involving a strange hadron and a photon. We use SuperKEKB electron-positron collisions corresponding to $189~\mathrm{fb}^{-1}$ of…

We have searched for neutrinoless $\tau$ lepton decays into $\ell$ and $V^0$, where $\ell$ stands for an electron or muon, and $V^0$ for a vector meson ($\phi$, $\omega$, $K^{*0}$ or $\bar{K}^{*0}$), using 543 fb$^{-1}$ of data collected…

We present the first measurement of the ratio of branching fractions of inclusive semileptonic $B$-meson decays, $R(X_{e/\mu}) = \mathcal{B}(B\to X \, e \, \nu) / \mathcal{B}(B\to X \, \mu \, \nu)$, a precision test of electron-muon…

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…