Related papers: The Belle II Physics Book

This paper reports a study of $B \to K^{*}\gamma$ decays using $62.8\pm 0.6$ fb$^{-1}$ of data collected during 2019--2020 by the Belle II experiment at the SuperKEKB $e^{+}e^{-}$ asymmetric-energy collider, corresponding to $(68.2 \pm 0.8)…

B-factories provide a unique environment to test the standard model in search for new physics. The Belle and Belle II experiments succeeded each other at KEK, in Tsukuba, Japan. During its lifetime, Belle collected $1{\,ab}^{-1}$ of data;…

The Belle II experiment is presently in phase-2 operation at the SuperKEKB electron-positron collider in KEK (Tsukuba, Japan). The detector is an upgrade of the Belle experiment at the KEKB collider and it is optimized for the study of rare…

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…

Belle II has recently reported the new measurement ${\cal B}(B^+\to K^+\nu\bar\nu)=(2.3\pm0.7)\times 10^{-5}$ \cite{Belle-II:2023esi} which is two times larger than their previous result (although consistent within errors) and about…

Upgrading the SuperKEKB electron-positron collider with polarized electron beams opens a new program of precision physics at a center-of-mass energy of 10.58 GeV. This white paper describes the physics potential of this `Chiral Belle'…

We report on recent results obtained by the Belle II experiment related to searches for beyond-the-standard-model physics. The $B$ meson decay data sample used corresponds to an integrated luminosity of $L = 189$ fb$^{-1}$. In recent years,…

We report a search for lepton-flavor-violating decays $\tau^- \to \ell^- \phi$ ($\ell^- =e^-,\mu^-$) at the Belle II experiment, using a sample of electron-positron data produced at the SuperKEKB collider in 2019-2021 and corresponding to…

The Belle II experiment will measure the rare decays $B\to K\nu\nu$ and $B\to K^* \nu\nu$ with increased sensitivity which can hence be expected to serve as a very efficient probe of new physics. We calculate the relevant branching ratios…

This article reports the first operation of a double-sided CMOS pixelated ladder in a collider experiment, namely in the inner tracker volume of the Belle II experiment during the Phase 2 run of the SuperKEKB collider. Design and…

We report the recent measurements performed using the data sample collected from 2019 to 2022 by the Belle~II experiment~\cite{Belle2:TDR} at $\Upsilon(4S)$ resonance, corresponding to an integrated luminosity of $362~\mathrm{fb}^{-1}$. We…

We present measurements of $B \to K{}^{*}(892)\gamma$ decays using $365\,{\rm fb}^{-1}$ of data collected from 2019 to 2022 by the Belle~II experiment at the SuperKEKB asymmetric-energy $e^+e^-$ collider. The data sample contains $(387 \pm…

In 2019 the Belle II experiment started data taking at the asymmetric SuperKEKB collider (KEK, Japan) operating at the Y(4S) resonance. Belle II will search for new physics beyond the Standard Model by collecting an integrated luminosity of…

The Belle experiment at the KEKB electron-positron collider is expected to have collected close to one billion $\Upsilon$(4S) events by the time it comes to an end in 2009. An upgrade to KEKB has been proposed. It is designed for an order…

We report a measurement of the $D^0$ and $D^+$ lifetimes using $D^0\to K^-\pi^+$ and $D^+\to K^-\pi^+\pi^+$ decays reconstructed in $e^+e^-\to c\bar{c}$ data recorded by the Belle II experiment at the SuperKEKB asymmetric-energy $e^+e^-$…

Using the Belle detector we study the characteristics of beam collisions at the KEKB 3.5 GeV $e^+$ on 8 GeV $e^-$ asymmetric energy collider. We investigate the collision timing {\tip} and its $z$-coordinate along the beam axis {\zip} as a…

We report a study of $B \to J/\psi(\ell^{+}\ell^{-})K$ decays, where $\ell$ represents an electron or a muon, using $e^{+}e^{-}$ collisions at the $\Upsilon(4S)$ resonance. The data were collected by the Belle II experiment at the SuperKEKB…

SuperKEKB is an electron-positron asymmetric-energy collider to search new physics phenomena appeared in B-meson decays. In order to accomplish this purpose, 40 times the luminosity as high as the KEKB collider is demanded. The strategy is…

With the advent of Belle II and the LHCb upgrade, the precision measurements of various B-Physics observables are on cards. This holds significant potential for delving into physics beyond the standard model of electroweak interactions.…

We report the first search for a non-standard-model resonance decaying into $\tau$ pairs in $e^{+}e^{-}\rightarrow \mu^{+}\mu^{-} \tau^+\tau^-$ events in the 3.6-10 GeV/$c^{2}$ mass range. We use a 62.8 fb$^{-1}$ sample of $e^+e^-$…