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A bstract Using the data samples of 102 million Υ(1 S ) and 158 million Υ(2 S ) events collected by the Belle detector, we search for a pentaquark state in the pJ/ψ final state from Υ(1 , 2 S ) inclusive decays. Here, the charge-conjugate is included. We observe clear pJ/ψ production in Υ(1 , 2 S ) decays and measure the branching fractions to be and . We also measure the cross section of inclusive pJ/ψ production in e + e − annihilation to be σ ( e + e − → pJ/ψ + anything ) = [108 ± 11( stat. ) ± 6( syst. )] fb at GeV using an 89 . 5 fb − 1 continuum data sample. There is no significant P c (4312) + , P c (4440) + or P c (4457) + signal found in the pJ/ψ final states in Υ(1 , 2 S ) inclusive decays. We determine the upper limits of to be at the 10 − 6 level.

A bstract We present the first measurement of the branching fraction of the singly Cabibbo-suppressed (SCS) decay Λ c + → pη ′ with η ′ → ηπ + π − , using a data sample corresponding to an integrated luminosity of 981 fb − 1 , collected by the Belle detector at the KEKB e + e − asymmetric-energy collider. A significant Λ c + → pη ′ signal is observed for the first time with a signal significance of 5.4 σ . The relative branching fraction with respect to the normalization mode Λ c + → pK − π + is measured to be B Λ c + → pη ′ B Λ c + → pK − π + = 7.54 ± 1.32 ± 0.73 × 10 − 3 , where the uncertainties are statistical and systematic, respectively. Using the world-average value of B Λ c + → pK − π + = (6 . 28 ± 0 . 32) × 10 − 2 , we obtain B Λ c + → pη ′ = 4.73 ± 0.82 ± 0.46 ± 0.24 × 10 − 4 , where the uncertainties are statistical, systematic, and from B Λ c + → pK − π + , respectively.

A bstract We present a search for the lepton-flavor-violating decays B s 0 → ℓ ∓ τ ± , where ℓ = e, μ , using the full data sample of 121 fb − 1 collected at the Υ(5 S ) resonance with the Belle detector at the KEKB asymmetric-energy e + e − collider. We use B s 0 B ¯ s 0 events in which one B s 0 meson is reconstructed in a semileptonic decay mode and the other in the signal mode. We find no evidence for B s 0 → ℓ ∓ τ ± decays and set upper limits on their branching fractions at 90% confidence level as B ( B s 0 → e ∓ τ ± ) < 14 × 10 − 4 and B ( B s 0 → μ ∓ τ ± ) < 7 . 3 × 10 − 4 . Our result represents the first upper limit on the B s 0 → e ∓ τ ± decay rate.

A bstract We measure the cross section of e + e − → η c J/ψ at the Υ( nS )( n = 1–5) on-resonance and 10.52 GeV off-resonance energy points using the full data sample collected by the Belle detector with an integrated luminosity of 955 fb − 1 . We also search for double charmonium production in e + e − → η c J/ψ via initial state radiation near the η c J/ψ threshold. No evident signal of the double charmonium state is found, but evidence for the e + e − → η c J/ψ process is found with a statistical significance greater than 3 . 3 σ near the η c J/ψ threshold. The average cross section near the threshold is measured and upper limits of cross sections are set for other regions.

We report a search for a heavy neutral lepton (HNL) that mixes predominantly with \\(\\nu_\\tau\\). The search utilizes data collected with the Belle detector at the KEKB asymmetric energy \\(e^+ e^-\\) collider. The data sample was collected at and just below the center-of-mass energies of the \\(\\Upsilon(4S)\\) and \\(\\Upsilon(5S)\\) resonances and has an integrated luminosity of \\(915~\\textrm{fb}^{-1}\\), corresponding to \\((836\\pm 12)\\times 10^6\\) \\(e^+e^\\to\\tau^+\\tau^-\\) events. We search for production of the HNL (denoted \\(N\\)) in the decay \\(\\tau^-\\to \\pi^- N\\) followed by its decay via \\(N \\to \\mu^+\\mu^- \\nu_\\tau\\). The search focuses on the parameter-space region in which the HNL is long lived, so that the \\(\\mu^+\\mu^-\\) originate from a common vertex that is significantly displaced from the collision point of the KEKB beams. Consistent with the expected background yield, one event is observed in the data sample after application of all the event-selection criteria. We report limits on the mixing parameter of the HNL with the \\(\\tau\\) neutrino as a function of the HNL mass.

Using a data sample of 980 fb-1 collected with the Belle detector at the KEKB asymmetric-energy e+e- collider, we study for the first time the singly Cabibbo-suppressed decays Ω0c → Ξ¯π+ and Ω¯K+ and the doubly Cabibbo-suppressed decay Ω0c → Ξ¯ K+. Evidence for an Ω0c signal in the Ω0c → Ξ¯π+ mode is reported with a significance of 4.5σ including systematic uncertainties.

Charged lepton flavor violation is forbidden in the Standard Model but possible in several new physics scenarios. In many of these models, the radiative decays τ± → ℓ±γ (ℓ = e, μ) are predicted to have a sizeable probability, making them particularly interesting channels to search at various experiments. An updated search via τ± → ℓ±γ using full data of the Belle experiment, corresponding to an integrated luminosity of 988 fb–1, is reported for charged lepton flavor violation. No significant excess over background predictions from the Standard Model is observed, and the upper limits on the branching fractions, B(τ± → μ±γ) ≤ 4.2 × 10–8 and B(τ± → e±γ) ≤ 5.6 × 10–8, are set at 90% confidence level.

We report the first measurement of the exclusive cross sections e+e- → $B\\overline{B}$, e+e- → $B{\\overline{B}}^{\\ast }$, and e+e- → ${B}^{\\ast }{\\overline{B}}^{\\ast }$ in the energy range from 10.63 GeV to 11.02 GeV. The B mesons are fully reconstructed in a large number of hadronic final states and the three channels are identified using a beam-constrained-mass variable. The shapes of the exclusive cross sections show oscillatory behavior with several maxima and minima. The results are obtained using data collected by the Belle experiment at the KEKB asymmetric-energy e+e- collider.

We present the first model-independent measurement of the CKM unitarity triangle angle Φ3 using B±→ D( \\( {K}_{\\mathrm{S}}^0 \\) π+π–π0) K± decays, where D indicates either a D0 or \\( \\overline{D} \\) 0 meson. Measurements of the strong-phase difference of the D → \\( {K}_{\\mathrm{S}}^0 \\) π+π–π0 amplitude obtained from CLEO-c data are used as input. This analysis is based on the full Belle data set of $772 × 10^6 B$ \\( \\overline{B} \\) events collected at the Υ(4S) resonance. We obtain Φ3 = ( \\( {5.7}_{-8.8}^{+10.2} \\) ±3.5±5.7)° and the suppressed amplitude ratio rB = 0.323±0.147±0.023±0.051. Here the first uncertainty is statistical, the second is the experimental systematic, and the third is due to the precision of the strong-phase parameters measured from CLEO-c data. The 95% confidence interval on Φ3 is (–29.7, 109.5)°, which is consistent with the current world average.

The search for flavour-changing neutral current effects in \\(B\\)-meson decays is a powerful probe of physics beyond the Standard Model. Deviations from SM behaviour are often quantified by extracting the preferred values of the Wilson coefficients of an operator product expansion. We use the FlavBit module of the GAMBIT package to perform a simultaneous global fit of the Wilson coefficients \\(C_7\\), \\(C_9\\), and \\(C_{10}\\) using a combination of all current data on \\(b \\to s \\mu^+ \\mu^-\\) transitions. We further extend previous analyses by accounting for the correlated theoretical uncertainties at each point in the Wilson coefficient parameter space, rather than deriving the uncertainties from a Standard Model calculation. We find that the best fit deviates from the SM value with a significance of 6.6\\(\\sigma\\). The largest deviation is associated with a vector coupling of muons to \\(b\\) and \\(s\\) quarks.