Related papers: Studies on $\tau$ decays at Belle II

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.…

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 analyze the $\tau^-\to(K\pi)^-\nu_\tau$ decays within an effective field theory description of heavy new physics (NP) modifying the SM left-handed weak charged current and include refined SM input for the participant meson form factors…

$L_\mu -L_\tau$ gauge boson ($Z'$) with a mass in the MeV to GeV region can resolve not only the muon $g-2$ excess, but also the gap in the high-energy cosmic neutrino spectrum at IceCube. It was recently proposed that such a light gauge…

The BaBar collaboration has accumulated over 400 million tau-pairs which can be used to study charged leptonic and hadronic weak currents to unprecedented precision. This note presents results on lepton universality, measurements of |V_us|,…

The anomalous magnetic moment of the tau lepton, $a_{\tau}$, represents a fundamental test of the Standard Model (SM) and a high-sensitivity probe for New Physics in the third generation of leptons. Due to the tau's extremely short…

In this work, we study the lepton number violating tau decays via two intermediate on-shell Majorana neutrinos $N_j$ into two charged pions, and a charged lepton $\tau^{\pm} \to \pi^{\pm} N_j \to \pi^{\pm} \pi^{\pm} \ell^{\mp}$. We consider…

Since 1999, the B-factories collaborations BaBar and Belle have accumulated and studied large samples of tau lepton pairs. We summarize in the following the most interesting recent results.

Precision studies of flavour-changing processes involving quarks and leptons provide a number of ways to improve knowledge of the Standard Model and search for physics beyond it. There are excellent short- and mid-term prospects for…

Semileptonic exclusive tau decays in the Standard Model are reviewed. As it is well-known, they are a privileged arena to learn about low-energy hadronization. They also allow for a number of clean new physics tests, which have attracted…

We report measurements of branching fractions of $\tau$ lepton decays to final states with a $K^{0}_{S}$ meson using a 669 fb$^{-1}$ data sample accumulated with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. The…

We have searched for neutrinoless tau lepton decays into three charged leptons using an 87.1 fb^{-1} data sample collected with the Belle detector at the KEKB e^+e^- collider. Since the number of signal candidate events is compatible with…

We report a measurement of the electric dipole moment of the $\tau$ lepton ($d_\tau$) using an 833~fb$^{-1}$ data sample collected near the $\Upsilon(4S)$ resonance, with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider.…

This thesis presents a study of the decays $\tau\rightarrow e\nu\overline{\nu}$ identified after a selection of $\tau^+\tau^-$ events produced in $e^+e^-$ collisions at LEP. These collisions, predominantly mediated by a $Z^0$ boson, offer a…

This article summarizes recent developments in $B\to D^{(\ast)}\tau\nu$ decays. We explain how to extract the tau lepton's production properties from the kinematics of its decay products. The focus is on hadronic tau decays, which are most…

The Belle II experiment at the SuperKEKB energy-asymmetric $e^+e^-$ collider is an upgrade of the B factory facility at KEK in Tsukuba, Japan. The experiment began operation in 2019 and aims to record a factor of 50 times more data than its…

With the expected large increase in data sets, previously not measured decays will be studied at Belle II. We derive standard model predictions for the $B\to X_u \tau\bar\nu$ decay rate and distributions. The region in the lepton energy…

A new muon and K_Long detector based on scintillators will be used for the endcap and inner barrel regions in the Belle II experiment, currently under construction. The increased luminosity of the e+e- SuperKEKB collider entails challenging…

When looking for heavy ($\mathcal{O}$(few TeV)) New Physics, the most efficient way to benefit from both high and low-energy measurements simultaneously is the use of the Standard Model Effective Field Theory (SMEFT). In this talk I…

Large numbers of $\tau$ leptons are produced at Belle II. These could potentially decay into sterile neutrinos that, for the mass range under consideration, are typically long-lived, leading to displaced-vertex signatures. Here, we study a…