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A<sc>bstract</sc> We perform the first search forCPviolation in$$ {D}_{(s)}^{+}\to {K}_S^0{K}^{-}{\pi}^{+}{\pi}^{+} $$ $D_{\left(s\right)}^{+}\to K_S^0{K}^{-}{\pi }^{+}{\pi }^{+}$decays. We use a combined data set from the Belle and Belle II experiments, which studye⁺e⁻collisions at center-of-mass energies at or near the Υ(4S) resonance. We use 980 fb⁻¹of data from Belle and 428 fb⁻¹of data from Belle II. We measure sixCP-violating asymmetries that are based on triple products and quadruple products of the momenta of final-state particles, and also the particles’ helicity angles. We obtain a precision at the level of 0.5% for$$ {D}^{+}\to {K}_S^0{K}^{-}{\pi}^{+}{\pi}^{+} $$ $D^{+}\to K_S^0{K}^{-}{\pi }^{+}{\pi }^{+}$decays, and better than 0.3% for$$ {D}_s^{+}\to {K}_S^0{K}^{-}{\pi}^{+}{\pi}^{+} $$ $D_s^{+}\to K_S^0{K}^{-}{\pi }^{+}{\pi }^{+}$decays. No evidence ofCPviolation is found. Our results for the triple-product asymmetries are the most precise to date for singly-Cabibbo-suppressedD⁺decays. Our results for the other asymmetries are the first such measurements performed for charm decays. 

We measure the branching fraction and $CP$-violating flavor-dependent rate asymmetry of $B^0\to {\pi }^0{\pi }^0$decays reconstructed using the Belle II detector in an electron-positron collision sample containing $387\times {10}^6\mathrm{\Upsilon }\left(4S\right)$mesons. Using an optimized event selection, we find $125\pm 20$signal decays in a fit to background-discriminating and flavor-sensitive distributions. The resulting branching fraction is $(1.25\pm 0.23)\times {10}^{-6}$and the $CP$-violating asymmetry is $0.03\pm 0.30$. Published by the American Physical Society2025 

A<sc>bstract</sc> We report measurements of the absolute branching fractions$$\mathcal{B}\left({B}_{s}^{0}\to {D}_{s}^{\pm }X\right)$$,$$\mathcal{B}\left({B}_{s}^{0}\to {D}^{0}/{\overline{D} }^{0}X\right)$$, and$$\mathcal{B}\left({B}_{s}^{0}\to {D}^{\pm }X\right)$$, where the latter is measured for the first time. The results are based on a 121.4 fb⁻¹data sample collected at the Υ(10860) resonance by the Belle detector at the KEKB asymmetric-energye⁺e⁻collider. We reconstruct one$${B}_{s}^{0}$$meson in$${e}^{+}{e}^{-}\to \Upsilon\left(10860\right)\to {B}_{s}^{*}{\overline{B} }_{s}^{*}$$events and measure yields of$${D}_{s}^{+}$$,D⁰, andD⁺mesons in the rest of the event. We obtain$$\mathcal{B}\left({B}_{s}^{0}\to {D}_{s}^{\pm }X\right)=\left(68.6\pm 7.2\pm 4.0\right)\%$$,$$\mathcal{B}\left({B}_{s}^{0}\to {D}^{0}/{\overline{D} }^{0}X\right)=\left(21.5\pm 6.1\pm 1.8\right)\%$$, and$$\mathcal{B}\left({B}_{s}^{0}\to {D}^{\pm }X\right)=\left(12.6\pm 4.6\pm 1.3\right)\%$$, where the first uncertainty is statistical and the second is systematic. Averaging with previous Belle measurements gives$$\mathcal{B}\left({B}_{s}^{0}\to {D}_{s}^{\pm }X\right)=\left(63.4\pm 4.5\pm 2.2\right)\%$$and$$\mathcal{B}\left({B}_{s}^{0}\to {D}^{0}/{\overline{D} }^{0}X\right)=\left(23.9\pm 4.1\pm 1.8\right)\%$$. For the$${B}_{s}^{0}$$production fraction at the Υ(10860), we find$${f}_{s}=\left({21.4}_{-1.7}^{+1.5}\right)\%$$. 

Abstract A series of data samples was collected with the Belle II detector at the SuperKEKB collider from March 2019 to June 2022. We determine the integrated luminosities of these data samples using three distinct methodologies involving Bhabha (), digamma (), and dimuon () events. The total integrated luminosity obtained with Bhabha, digamma, and dimuon events is (426.88 ± 0.03 ± 2.61) fb⁻¹, (429.28 ± 0.03 ± 2.62) fb⁻¹, and (423.99 ± 0.04 ± 3.83) fb⁻¹, where the first uncertainties are statistical and the second are systematic. The resulting total integrated luminosity obtained from the combination of the three methods is (427.87 ± 2.01) fb⁻¹. 

We present a measurement of the branching fraction and time-dependent charge-parity ( $CP$) decay-rate asymmetries in $B^0\to J/\psi {\pi }^0$decays. The data sample was collected with the Belle II detector at the SuperKEKB asymmetric $e^{+}{e}^{-}$collider in 2019–2022 and contains $(387\pm 6)\times {10}^{6}B\overline{B}$meson pairs from $\mathrm{\Upsilon }\left(4S\right)$decays. We reconstruct $392\pm 24$signal decays and fit the $CP$parameters from the distribution of the proper-decay-time difference of the two $B$mesons. We measure the branching fraction to be $\left({\mathcal{B}}^0\to J/\psi {\pi }^0\right)=(2.00\pm 0.12\pm 0.09)\times {10}^{-5}$and the direct and mixing-induced $CP$asymmetries to be $C_{CP}=0.13\pm 0.12\pm 0.03$and $S_{CP}=-0.88\pm 0.17\pm 0.03$, respectively, where the first uncertainties are statistical and the second are systematic. We observe mixing-induced $CP$violation with a significance of 5.0 standard deviations for the first time in this mode. Published by the American Physical Society2025 

We present a search for the baryon number $B$and lepton number $L$violating decays ${\tau }^{-}\to \mathrm{\Lambda }{\pi }^{-}$and ${\tau }^{-}\to \overline{\mathrm{\Lambda }}{\pi }^{-}$produced from the $e^{+}{e}^{-}\to {\tau }^{+}{\tau }^{-}$process, using a $364{\mathrm{fb}}^{-1}$data sample collected by the Belle II experiment at the SuperKEKB collider. No evidence of signal is found in either decay mode, which have $\left|\mathrm{\Delta }\right(B-L\left)\right|$equal to 2 and 0, respectively. Upper limits at 90% credibility level on the branching fractions of ${\tau }^{-}\to \mathrm{\Lambda }{\pi }^{-}$and ${\tau }^{-}\to \overline{\mathrm{\Lambda }}{\pi }^{-}$are determined to be $4.7\times {10}^{-8}$and $4.3\times {10}^{-8}$, respectively. Published by the American Physical Society2024 

We report measurements of time-dependent $CP$asymmetries in $B^0\to K_S^0{\pi }^0\gamma$decays based on a data sample of $(388\pm 6)\times {10}^{6}B\overline{B}$events collected at the $\mathrm{\Upsilon }\left(4S\right)$resonance with the Belle II detector. The Belle II experiment operates at the SuperKEKB asymmetric-energy $e^{+}{e}^{-}$collider. We measure decay-time distributions to determine $CP$-violating parameters $S$and $C$. We determine these parameters for two ranges of $K_S^0{\pi }^0$invariant mass: $m\left(K_S^0{\pi }^0\right)\in (0.8,1.0)\mathrm{GeV}/c^2$, which is dominated by $B^0\to K^{*0}(\to K_S^0{\pi }^0)\gamma$decays, and a complementary region $m\left(K_S^0{\pi }^0\right)\in (0.6,0.8)\cup (1.0,1.8)\mathrm{GeV}/c^2$. Our results have improved precision as compared to previous measurements and are consistent with theory predictions. Published by the American Physical Society2025 

We describe a measurement of charge-parity ( $CP$) violation asymmetries in $B^0\to {\eta }^{\prime }{K}_{\mathrm{S}}^0$decays using Belle II data. We consider ${\eta }^{\prime }\to \eta (\to \gamma \gamma ){\pi }^{+}{\pi }^{-}$and ${\eta }^{\prime }\to \rho (\to {\pi }^{+}{\pi }^{-})\gamma$decays. The data were collected at the SuperKEKB asymmetric-energy $e^{+}{e}^{-}$collider between the years 2019 and 2022, and contain $(387\pm 6)\times {10}^6$bottom-antibottom meson pairs. We reconstruct $829\pm 35$signal decays and extract the $CP$violating parameters from a fit to the distribution of the proper-decay-time difference between the two $B$mesons. The measured direct and mixing-induced $CP$asymmetries are $C_{{\eta }^{\prime }{K}_{\mathrm{S}}^0}=-0.19\pm 0.08\pm 0.03$and $S_{{\eta }^{\prime }{K}_{\mathrm{S}}^0}=+0.67\pm 0.10\pm 0.03$, respectively, where the first uncertainties are statistical and the second are systematic. These results are in agreement with current world averages and standard model predictions. Published by the American Physical Society2024 

A<sc>bstract</sc> An angular analysis ofB⁰→ K^*0e⁺e⁻decays is presented using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb⁻¹. The analysis is performed in the region of the dilepton invariant mass squared of 1.1–6.0 GeV²/c⁴. In addition, a test of lepton flavour universality is performed by comparing the obtained angular observables with those measured inB⁰→ K^*0μ⁺μ⁻decays. In general, the angular observables are found to be consistent with the Standard Model expectations as well as with global analyses of otherb → sℓ⁺ℓ⁻processes, whereℓis either a muon or an electron. No sign of lepton-flavour-violating effects is observed. 

A<sc>bstract</sc> A search for the decay$$ {B}_c^{+} $$ $B_c^{+}$→ χ_c1(3872)π⁺is reported using proton-proton collision data collected with the LHCb detector between 2011 and 2018 at centre-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb⁻¹. No significant signal is observed. Using the decay$$ {B}_c^{+} $$ $B_c^{+}$→ψ(2S)π⁺as a normalisation channel, an upper limit for the ratio of branching fractions$$ {\mathcal{R}}_{\psi (2S)}^{\chi_{c1}(3872)}=\frac{{\mathcal{B}}_{B_c^{+}\to {\chi}_{c1}(3872){\pi}^{+}}}{{\mathcal{B}}_{B_c^{+}\to \psi (2S){\pi}^{+}}}\times \frac{{\mathcal{B}}_{\chi_{c1}(3872)\to J/\psi {\pi}^{+}{\pi}^{-}}}{{\mathcal{B}}_{\psi (2S)\to J/\psi {\pi}^{+}{\pi}^{-}}}<0.05(0.06), $$ $R_{\psi \left(2S\right)}^{{\chi }_{c1}\left(3872\right)}=\frac{B_{B_c^{+}\to {\chi }_{c1}\left(3872\right){\pi }^{+}}}{B_{B_c^{+}\to \psi \left(2S\right){\pi }^{+}}}\times \frac{B_{{\chi }_{c1}\left(3872\right)\to J/\psi {\pi }^{+}{\pi }^{-}}}{B_{\psi \left(2S\right)\to J/\psi {\pi }^{+}{\pi }^{-}}}<0.05\left(0.06\right),$ is set at the 90 (95)% confidence level.