Measurement of Angular Coefficients of B[over ¯]→D^{*}ℓν[over ¯]_{ℓ}: Implications for |V_{cb}| and Tests of Lepton Flavor Universality.

We measure the complete set of angular coefficients J_{i} for exclusive B[over ¯]→D^{*}ℓν[over ¯]_{ℓ} decays (ℓ=e, μ). Our analysis uses the full 711  fb^{-1} Belle dataset with hadronic tag-side reconstruction. The results allow us to extract the form factors describing the B[over ¯]→D^{*} transition and the Cabibbo-Kobayashi-Maskawa matrix element |V_{cb}|.

Search for Rare b→dℓ^{+}ℓ^{-} Transitions at Belle.

We present the results of a search for the b→dℓ^{+}ℓ^{-} flavor-changing neutral-current rare decays B^{+,0}→(η,ω,π^{+,0},ρ^{+,0})e^{+}e^{-} and B^{+,0}→(η,ω,π^{0},ρ^{+})μ^{+}μ^{-} using a 711  fb^{-1} data sample that contains 772×10^{6}  BB[over ¯] events. The data were collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. We find no evidence for signal and set upper limits on branching fractions at the 90% confidence level in the range (3.

Measurements of the Branching Fraction, Polarization, and CP Asymmetry for the Decay B^{0}→ωω.

We present a comprehensive study of B^{0}→ωω decays using 772×10^{6}  BB[over ¯] pairs collected with the Belle detector at the KEKB e^{+}e^{-} collider. This process is a suppressed charmless decay into two vector mesons and can exhibit interesting polarization and CP violation. The decay is observed for the first time with a significance of 7.

Search for Baryon-Number-Violating Processes in B^{-} Decays to the Ξ[over ¯]_{c}^{0}Λ[over ¯]_{c}^{-} Final State.

We report the results of the first search for B^{-} decays to the Ξ[over ¯]_{c}^{0}Λ[over ¯]_{c}^{-} final state using 711  fb^{-1} of data collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. The results are interpreted in terms of both direct baryon-number-violating B^{-} decay and Ξ_{c}^{0}-Ξ[over ¯]_{c}^{0} oscillations which follow the standard model decay B^{-}→Ξ_{c}^{0}Λ[over ¯]_{c}^{-}. We observe no evidence for baryon number violation and set the 95% confidence-level upper limits on the ratio of baryon-number-violating and standard model branching fractions B(B^{-}→Ξ[over ¯]_{c}^{0}Λ[over ¯]_{c}^{-})/B(B^{-}→Ξ_{c}^{0}Λ[over ¯]_{c}^{-}) to be <2.

Observation of Strong Nuclear Suppression in Exclusive J/ψ Photoproduction in Au+Au Ultraperipheral Collisions at RHIC.

We report a measurement of exclusive J/ψ and ψ(2s) photoproduction in Au+Au ultraperipheral collisions at sqrt[s_{NN}]=200  GeV using the STAR detector. For the first time, (i) the ψ(2s) photoproduction in midrapidity at the Relativistic Heavy-Ion Collider has been experimentally measured; (ii) nuclear suppression factors are measured for both the coherent and incoherent J/ψ production. At average photon-nucleon center-of-mass energy of 25.

First Measurement of R(X_{τ/ℓ}) as an Inclusive Test of the b→cτν Anomaly.

We measure the tau-to-light-lepton ratio of inclusive B-meson branching fractions R(X_{τ/ℓ})≡B(B→Xτν)/B(B→Xℓν), where ℓ indicates an electron or muon, and thereby test the universality of charged-current weak interactions. We select events that have one fully reconstructed B meson and a charged lepton candidate from 189  fb^{-1} of electron-positron collision data collected with the Belle II detector. We find R(X_{τ/ℓ})=0.

Search for a Heavy Neutrino in τ Decays at Belle.

We report on a search for a heavy Majorana neutrino in the decays τ^{-}→π^{-}ν_{h}, ν_{h}→π^{±}ℓ^{∓}, ℓ=e, μ. The results are obtained using the full data sample of 988  fb^{-1} collected with the Belle detector at the KEKB asymmetric energy e^{+}e^{-} collider, which contains 912×10^{6}  ττ pairs. We observe no significant signal and set 95% CL upper limits on the couplings of the heavy right-handed neutrinos to the conventional standard model left-handed neutrinos in the mass range 0.

Hyperon Polarization along the Beam Direction Relative to the Second and Third Harmonic Event Planes in Isobar Collisions at sqrt[s_{NN}]=200 GeV.

The polarization of Λ and Λ[over ¯] hyperons along the beam direction has been measured relative to the second and third harmonic event planes in isobar Ru+Ru and Zr+Zr collisions at sqrt[s_{NN}]=200  GeV. This is the first experimental evidence of the hyperon polarization by the triangular flow originating from the initial density fluctuations. The amplitudes of the sine modulation for the second and third harmonic results are comparable in magnitude, increase from central to peripheral collisions, and show a mild p_{T} dependence.

Tests of Light-Lepton Universality in Angular Asymmetries of B^{0}→D^{*-}ℓν Decays.

We present the first comprehensive tests of the universality of the light leptons in the angular distributions of semileptonic B^{0}-meson decays to charged spin-1 charmed mesons. We measure five angular-asymmetry observables as functions of the decay recoil that are sensitive to lepton-universality-violating contributions. We use events where one neutral B is fully reconstructed in ϒ(4S)→BB[over ¯] decays in data corresponding to 189  fb^{-1} integrated luminosity from electron-positron collisions collected with the Belle II detector.

Precise Measurement of the D_{s}^{+} Lifetime at Belle II.

We measure the lifetime of the D_{s}^{+} meson using a data sample of 207  fb^{-1} collected by the Belle II experiment running at the SuperKEKB asymmetric-energy e^{+}e^{-} collider. The lifetime is determined by fitting the decay-time distribution of a sample of 116×10^{3} D_{s}^{+}→ϕπ^{+} decays. Our result is τ_{D_{s}^{+}}=(499.

Search for a τ^{+}τ^{-} Resonance in e^{+}e^{-}→μ^{+}μ^{-}τ^{+}τ^{-} Events with the Belle II Experiment.

We report the first search for a nonstandard-model resonance decaying into τ pairs in e^{+}e^{-}→μ^{+}μ^{-}τ^{+}τ^{-} events in the 3.6-10  GeV/c^{2} mass range. We use a 62.

Measurement of CP Violation in B^{0}→K_{S}^{0}π^{0} Decays at Belle II.

We report a measurement of the CP-violating parameters C and S in B^{0}→K_{S}^{0}π^{0} decays at Belle II using a sample of 387×10^{6}  BB[over ¯] events recorded in e^{+}e^{-} collisions at a center-of-mass energy corresponding to the ϒ(4S) resonance. These parameters are determined by fitting the proper decay-time distribution of a sample of 415 signal events. We obtain C=-0.

Erratum: Global Polarization of Ξ and Ω Hyperons in Au+Au Collisions at sqrt[s_{NN}]=200 GeV [Phys. Rev. Lett. 126, 162301 (2021)].

This corrects the article DOI: 10.1103/PhysRevLett.126.

Test of Light-Lepton Universality in the Rates of Inclusive Semileptonic B-Meson Decays at Belle II.

We present the first measurement of the ratio of branching fractions of inclusive semileptonic B-meson decays, R(X_{e/μ})=B(B→Xeν)/B(B→Xμν), a precision test of electron-muon universality, using data corresponding to 189  fb^{-1} from electron-positron collisions collected with the Belle II detector. In events where the partner B meson is fully reconstructed, we use fits to the lepton momentum spectra above 1.3  GeV/c to obtain R(X_{e/μ})=1.

First Measurement of the Michel Parameter ξ^{'} in the τ^{-}→μ^{-}ν[over ¯]_{μ}ν_{τ} Decay at Belle.

We report the first measurement of the Michel parameter ξ^{'} in the τ^{-}→μ^{-}ν[over ¯]_{μ}ν_{τ} decay with a new method proposed just recently. The measurement is based on the reconstruction of the τ^{-}→μ^{-}ν[over ¯]_{μ}ν_{τ} events with subsequent muon decay in flight in the Belle central drift chamber. The analyzed data sample of 988  fb^{-1} collected by the Belle detector corresponds to approximately 912×10^{6} τ^{+}τ^{-} pairs.

Search for the Lepton Flavor Violating Decays B^{+}→K^{+}τ^{±}ℓ^{∓} (ℓ=e, μ) at Belle.

We present a search for the lepton flavor violating decays B^{+}→K^{+}τ^{±}ℓ^{∓}, with ℓ=(e,μ), using the full data sample of 772×10^{6}  BB[over ¯] pairs recorded by the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. We use events in which one B meson is fully reconstructed in a hadronic decay mode. We find no evidence for B^{±}→K^{±}τℓ decays and set upper limits on their branching fractions at the 90% confidence level in the (1-3)×10^{-5} range.

Measurements of the Elliptic and Triangular Azimuthal Anisotropies in Central ^{3}He+Au, d+Au and p+Au Collisions at sqrt[s_{NN}]=200 GeV.

The elliptic (v_{2}) and triangular (v_{3}) azimuthal anisotropy coefficients in central ^{3}He+Au, d+Au, and p+Au collisions at sqrt[s_{NN}]=200  GeV are measured as a function of transverse momentum (p_{T}) at midrapidity (|η|<0.9), via the azimuthal angular correlation between two particles both at |η|<0.9.

Search for an Invisible Z^{'} in a Final State with Two Muons and Missing Energy at Belle II.

The L_{μ}-L_{τ} extension of the standard model predicts the existence of a lepton-flavor-universality-violating Z^{'} boson that couples only to the heavier lepton families. We search for such a Z^{'} through its invisible decay in the process e^{+}e^{-}→μ^{+}μ^{-}Z^{'}. We use a sample of electron-positron collisions at a center-of-mass energy of 10.

Observation of Directed Flow of Hypernuclei _{Λ}^{3}H and _{Λ}^{4}H in sqrt[s_{NN}]=3 GeV Au+Au Collisions at RHIC.

We report here the first observation of directed flow (v_{1}) of the hypernuclei _{Λ}^{3}H and _{Λ}^{4}H in mid-central Au+Au collisions at sqrt[s_{NN}]=3  GeV at RHIC. These data are taken as part of the beam energy scan program carried out by the STAR experiment. From 165×10^{6} events in 5%-40% centrality, about 8400 _{Λ}^{3}H and 5200 _{Λ}^{4}H candidates are reconstructed through two- and three-body decay channels.

Beam Energy Dependence of Triton Production and Yield Ratio (N_{t}×N_{p}/N_{d}^{2}) in Au+Au Collisions at RHIC.

We report the triton (t) production in midrapidity (|y|<0.5) Au+Au collisions at sqrt[s_{NN}]=7.7-200  GeV measured by the STAR experiment from the first phase of the beam energy scan at the Relativistic Heavy Ion Collider.

First Measurement of the B^{+}→π^{+}π^{0}π^{0} Branching Fraction and CP Asymmetry.

We study B^{+}→π^{+}π^{0}π^{0} using 711  fb^{-1} of data collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. We measure an inclusive branching fraction of (19.0±1.

Search for Lepton-Flavor-Violating τ Decays to a Lepton and an Invisible Boson at Belle II.

We search for lepton-flavor-violating τ^{-}→e^{-}α and τ^{-}→μ^{-}α decays, where α is an invisible spin-0 boson. The search uses electron-positron collisions at 10.58 GeV center-of-mass energy with an integrated luminosity of 62.

First Observation of Λπ^{+} and Λπ^{-} Signals near the K[over ¯]N(I=1) Mass Threshold in Λ_{c}^{+}→Λπ^{+}π^{+}π^{-} Decay.

Using the data sample of 980  fb^{-1} collected with the Belle detector operating at the KEKB asymmetric-energy e^{+}e^{-} collider, we present the results of an investigation of the Λπ^{+} and Λπ^{-} invariant mass distributions looking for substructure in the decay Λ_{c}^{+}→Λπ^{+}π^{+}π^{-}. We find a significant signal in each mass distribution. When interpreted as resonances, we find for the Λπ^{+} (Λπ^{-}) combination a mass of 1434.

Measurement of Sequential ϒ Suppression in Au+Au Collisions at sqrt[s_{NN}]=200 GeV with the STAR Experiment.

We report on measurements of sequential ϒ suppression in Au+Au collisions at sqrt[s_{NN}]=200  GeV with the STAR detector at the Relativistic Heavy Ion Collider (RHIC) through both the dielectron and dimuon decay channels. In the 0%-60% centrality class, the nuclear modification factors (R_{AA}), which quantify the level of yield suppression in heavy-ion collisions compared to p+p collisions, for ϒ(1S) and ϒ(2S) are 0.40±0.