Related papers: Dark Sector Physics at the Belle II Experiment

We report on measurements of branching fractions ($\mathcal{B}$) and CP-violating charge asymmetries ($\mathcal{A}_{\rm CP}$) of multibody charmless $B$ decays reconstructed by the Belle II experiment at the SuperKEKB electron-positron…

$K^0_SK^0_S$ production in two-photon collisions has been studied using a 397.6 fb$^{-1}$ data sample collected with the Belle detector at the KEKB $e^+e^-$ collider. For the first time the cross sections are measured in the two-photon…

High-luminosity e+ e- colliders at the GeV scale (flavor factories) have been recently recognized to be an ideal environment to search for a light weakly coupled vector boson U (dark photon) emerging in several new physics models able to…

SuperB is a next generation asymmetric e+e- flavor factory with a baseline luminosity of 10^36 cm^-2 s^-1, 50-100 times the peak luminosity of the existing B-factories. The physics motivation is presented and the complementarity with the…

We present a measurement of the branching fraction and longitudinal polarization of $B^0 \to \rho^+ \rho^-$ decays. SuperKEKB electron-positron collision data corresponding to 189~fb$^{-1}$ of integrated luminosity and containing $198…

In this proceeding, we report the recent measurements of the CKM angle \phi_1(\beta) using large data samples collected by the Belle and BaBar experiments. The experiments have collected more than 1 billion B anti-B pairs of data sample at…

We report on the design, operation, and performance of a novel proximity-focusing Ring Imaging Cherenkov (RICH) detector equipped with a multilayer focusing aerogel radiator, developed for the forward region of the Belle II spectrometer at…

The Belle and Belle II experiments have collected an 1.6 ab$^{-1}$ sample of $e^+e^-$ collision data at center-of-mass energies near the $\Upsilon(nS)$ resonances. In particular, the Belle II experiment collected a 19.2 fb$^{-1}$ sample of…

We summarize recent results on an array of CP violation measurements performed by the Belle experiment using the data collected near the Y(4S) and Y(5S) resonances at the KEKB asymmetric-energy e+e- collider.

We present recent measurements of semileptonic $B$-meson decays using a data sample collected at the $\Upsilon(4S)$ resonance by the Belle II experiment corresponding to an integrated luminosity of $189\,\mathrm{fb}^{-1}$. We determine the…

An excess in the branching fraction for $B^+ \to K^+ \nu\nu$ recently measured at Belle II may be a hint of new physics. We perform thorough likelihood analyses for different new physics scenarios such as $B \to KX$ with a new invisible…

We report a measurement of the $e^+e^- \to \pi^+\pi^-\pi^0$ cross section in the energy range from 0.62 to 3.50 GeV using an initial-state radiation technique. We use an $e^+e^-$ data sample corresponding to 191 $\text{fb}^{-1}$ of…

We present measurements of the branching fractions of eight $\overline B{}^0\to D^{(*)+} K^- K^{(*)0}_{(S)}$, $B^{-}\to D^{(*)0} K^- K^{(*)0}_{(S)}$ decay channels. The results are based on data from SuperKEKB electron-positron collisions…

The LHCb (Large Hadron Collider beauty) experiment at CERN aims at achieving a significantly higher luminosity than originally planned by means of two major upgrades: the Upgrade I that took place during the Long Shutdown 2 (LS2) and the…

We report the recent results related to $\pi-K$ interactions based on the data collected by the Belle experiment at the KEKB collider. This includes the branching fraction and $CP$ asymmetry measurements of $B^+\to K^+K^-\pi^+$ decay,…

We propose a new search for light scalar singlets in rare meson decays. For tiny interactions, the scalar is long-lived at detector scales and decays into displaced pairs of leptons or light mesons. We show that Belle II has a remarkable…

Dark photons with kinetic mixing are compelling mediators for the interactions between dark matter and Standard Model particles. While most experimental searches focus on fully visible or fully invisible decays of dark photons, we explore…

We report recent results on the charmonium and charmoniumlike states based on a large data sample recorded at the $\Upsilon(4S)$ and $\Upsilon(5S)$ resonances with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider.

Current searches for a dark photon in the mass range below 1 GeV require an electron-positron collider with a luminosity at the level of at least $10^{34}$ cm$^{-2}$s$^{-1}$. The challenge is that, at such low energies, the collider…

The LHCb detector at the LHC has shown a very successful initial operation and it is expected that the experiment will accumulate an integrated luminosity in proton-proton collisions of around 1 fb-1 in 2011. The data already collected are…