We present a measurement of angular observables and a test of lepton flavor universality in the $B\to K^{*}{\ell }^{+}{\ell }^{-}$ decay, where $\ell$ is either $e$ or $\mu$. The analysis is performed on a data sample corresponding to an integrated luminosity of $711{\mathrm{fb}}^{-1}$ containing $772\times 10^6$ $B\overline{B}$ pairs, collected at the $\mathrm{\Upsilon }(4S)$ resonance with the Belle detector at the asymmetric-energy $e^{+}{e}^{-}$ collider KEKB. The result is consistent with standard model (SM) expectations, where the largest discrepancy from a SM prediction is observed in the muon modes with a local significance of $2.6\sigma$.

With the full data sample of $772\times {10}^{6}B\overline{B}$ pairs recorded by the Belle detector at the KEKB electron-positron collider, the decay $\overline{B}\to D^{*}{\tau }^{-}{\overline{\nu }}_{\tau }$ is studied with the hadronic $\tau$ decays ${\tau }^{-}\to {\pi }^{-}{\nu }_{\tau }$ and ${\tau }^{-}\to {\rho }^{-}{\nu }_{\tau }$. The $\tau$ polarization $P_{\tau }(D^{*})$ in two-body hadronic $\tau$ decays is measured, as well as the ratio of the branching fractions $R(D^{*})=\mathcal{B}(\overline{B}\to D^{*}{\tau }^{-}{\overline{\nu }}_{\tau })/\mathcal{B}(\overline{B}\to D^{*}{\ell }^{-}{\overline{\nu }}_{\ell })$, where ${\ell }^{-}$ denotes an electron or a muon. Our results, $P_{\tau }(D^{*})=-0.38\pm 0.51{(\text{stat})}_{-0.16}^{+0.21}(\text{syst})$ and $R(D^{*})=0.270\pm 0.035{(\text{stat})}_{-0.025}^{+0.028}(\text{syst})$, are consistent with the theoretical predictions of the standard model. The polarization values of $P_{\tau }(D^{*})>+0.5$ are excluded at the 90% confidence level.

The K¯N system at threshold is a sensitive testing ground for low energy QCD, especially for the explicit chiral symmetry breaking. Therefore, we have measured the K-series X-rays of kaonic hydrogen atoms at the DAΦNE electron–positron collider of Laboratori Nazionali di Frascati, and have determined the most precise values of the strong-interaction energy-level shift and width of the 1s atomic state. As X-ray detectors, we used large-area silicon drift detectors having excellent energy and timing resolution, which were developed especially for the SIDDHARTA experiment. The shift and width were determined to be ϵ1s=−283±36(stat)±6(syst) eV and Γ1s=541±89(stat)±22(syst) eV, respectively. The new values will provide vital constraints on the theoretical description of the low-energy K¯N interaction

Delayed annihilation of antiprotons stopped in liquid helium has been observed, revealing that about 3.6% of stopped antiprotons are trapped in long-lived metastable states. No delayed component was found either in liquid nitrogen or in liquid argon. The observed time distribution of delayed annihilation shows fast-decaying components followed by a major part with a decay time constant of 3 μsec.

Measurements of anisotropic flow coefficients ($v_n$) and their cross-correlations using two- and multiparticle cumulant methods are reported in collisions of $pp$ at $\sqrt{s}=13\mathrm{TeV}$, $p\text{−}\mathrm{Pb}$ at a center-of-mass energy per nucleon pair $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$, Xe-Xe at $\sqrt{s_{\mathrm{NN}}}=5.44\mathrm{TeV}$, and Pb-Pb at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$ recorded with the ALICE detector. The multiplicity dependence of $v_n$ is studied in a very wide range from 20 to 3000 particles produced in the midrapidity region $|\eta |<0.8$ for the transverse momentum range $0.2<p_T<3.0\mathrm{GeV}/c$. An ordering of the coefficients $v_2>v_3>v_4$ is found in $pp$ and $p\text{−}\mathrm{Pb}$ collisions, similar to that seen in large collision systems, while a weak $v_2$ multiplicity dependence is observed relative to nucleus-nucleus collisions in the same multiplicity range. Using a novel subevent method, $v_2$ measured with four-particle cumulants is found to be compatible with that from six-particle cumulants in $pp$ and $p\text{−}\mathrm{Pb}$ collisions. The magnitude of the correlation between $v_n^2$ and $v_m^2$, evaluated with the symmetric cumulants $\mathrm{SC}(m,n)$ is observed to be positive at all multiplicities for $v_2$ and $v_4$, while for $v_2$ and $v_3$ it is negative and changes sign for multiplicities below 100, which may indicate a different $v_n$ fluctuation pattern in this multiplicity range. The observed long-range multiparticle azimuthal correlations in high multiplicity $pp$ and $p\text{−}\mathrm{Pb}$ collisions can neither be described by pythia 8 nor by impact-parameter-Glasma, music, and ultrarelativistic quantum molecular dynamics model calculations, and hence, provide new insights into the understanding of collective effects in small collision systems.