We report the results of the first search for the decay B_s^0→π^0π^0 using 121.4 fb^-1 of data collected at the Υ(5 S) resonance with the Belle detector at the KEKB asymmetric-energy e^+e^- collider. We observe no signal and set a 90% confidence level upper limit of 7.7× 10^-6 on the B_s^0→π^0π^0 decay branching fraction.

We search for the rare decay $B^{+}\rightarrow K^{+}\nu\bar{\nu}$ in a $362\ \rm{fb}^{-1}$ sample of electron-positron collisions at the $\Upsilon(4S)$ resonance collected with the Belle II detector at the SuperKEKB collider. We use the inclusive properties of the accompanying $B$ meson in $\Upsilon(4S) \to B\kern 0.18em\overline{\kern -0.18em B}{}$ events to suppress background from other decays of the signal $B$ candidate and light-quark pair production. We validate the measurement with an auxiliary analysis based on a conventional hadronic reconstruction of the accompanying $B$ meson. For background suppression, we exploit distinct signal features using machine learning methods tuned with simulated data. The signal-reconstruction efficiency and background suppression are validated through various control channels. The branching fraction is extracted in a maximum likelihood fit. Our inclusive and hadronic analyses yield consistent results for the $B^{+}\rightarrow K^{+}\nu\bar{\nu}$ branching fraction of $\left[2.7\pm 0.5(\mathrm{stat})\pm 0.5(\mathrm{syst})\right] \times 10^{-5}$ and $\left[1.1^{+0.9}_{-0.8}(\mathrm{stat}){}^{+0.8}_{-0.5}(\mathrm{syst})\right] \times 10^{-5}$, respectively. Combining the results, we determine the branching fraction of the decay $B^{+}\rightarrow K^{+}\nu\bar{\nu}$ to be $\left[2.3 \pm 0.5(\mathrm{stat})^{+0.5}_{-0.4}(\mathrm{syst})\right]\times 10^{-5}$, providing the first evidence for this decay at $3.5$ standard deviations. The combined result is $2.7$ standard deviations above the standard model expectation.

We report the first measurement of the $Q^2$ distribution of $X(3915)$ produced by single-tag two-photon interactions. The decay mode used is $X(3915) \rightarrow J/\psi\omega$. The covered $Q^2$ region is from 1.5 (GeV/$c$)$^2$ to 10.0 (GeV/$c$)$^2$. We observe $7.9\pm 3.1({\rm stat.})\pm 1.5({\rm syst.})$ events, where we expect $4.1\pm 0.7$ events based on the $Q^2=0$ result from the no-tag two-photon process, extrapolated to higher $Q^2$ region using the $c\bar{c}$ model of Schuler, Berends, and van Gulik. The shape of the distribution is also consistent with this model; we note that statistical uncertainties are large.

We observe the process $\Upsilon(2S)\to D_s^{(*)+} D_{sJ}^{-}$ and continuum production $e^+e^- \to D_s^{(*)+} D_{sJ}^- $ at $\sqrt{s} = 10.52$ GeV (and their charge conjugates) using the data samples collected by the Belle detector at KEKB, where $D_{sJ}^-$ is $D_{s1}(2536)^-$ or $D^{*}_{s2}(2573)^-$. Both $D_{sJ}^-$ states are identified through their decay into $\bar{K}\bar{D}^{(*)}$. We measure the products of branching fractions ${\cal B}(\Upsilon(2S) \to D_{s}^{(*)+} D_{sJ}^-) {\cal B}(D_{sJ}^-\to \bar{K} \bar{D}^{(*)})$ and the Born cross sections $\sigma^{\rm Born}(e^+e^- \to D_{s}^{(*)+} D_{sJ}^-) {\cal B}(D_{sJ}^-\to \bar{K} \bar{D}^{(*)})$, and then compare the ratios $R_1 \equiv {\cal B}(\Upsilon(2S)\to D_{s}^{(*)+} D_{sJ}^-)/{\cal B}(\Upsilon(2S)\to\mu^{+}\mu^-)$ for $\Upsilon(2S)$ decays and $R_2 \equiv \sigma^{\rm Born}(e^+e^-\to D_{s}^{(*)+}D_{sJ}^-)/\sigma^{\rm Born}(e^+e^-\to \mu^{+}\mu^-)$ for continuum production. We obtain $R_1/R_2 = 9.7\pm 2.3 \pm 1.1$, $6.8 \pm 2.1 \pm 0.8$, $10.2 \pm 3.3 \pm 2.5$, and $3.4 \pm 2.1 \pm 0.5$ for the $D_s^+ D_{s1}(2536)^-$, $D_s^{*+} D_{s1}(2536)^-$, $D_s^+ D_{s2}^{*}(2573)^{-}$, and $D_s^{*+} D_{s2}^{*}(2573)^{-}$ final states in the $D_{sJ}^-\to K^{-} \bar{D}^{(*)0}$ modes, respectively. Therefore, the strong decay is expected to dominate in the $\Upsilon(2S)\to D_{s}^{(*)+}D_{sJ}^-$ processes. We also measure the ratios of branching fractions ${\cal B}(D_{s1}(2536)^-\to K_S^0 D^{*}(2010)^{-})/{\cal B}(D_{s1}(2536)^-\to K^{-} D^{*}(2007)^0) = 0.48 \pm 0.07 \pm 0.02$ and ${\cal B}(D_{s2}^{*}(2573)^- \to K_S^0 D^-)/{\cal B}(D_{s2}^{*}(2573)^- \to K^{-}D^0) = 0.49 \pm 0.10 \pm 0.02$, which are consistent with isospin symmetry. The second ratio is the first measurement of this quantity. Here, the first uncertainties are statistical and the second are systematic.

We present a study of the $X(3872)$ lineshape in the decay $B \to X(3872)K\to D^0\overline{D}{}^{*0}K$ using a data sample of $772\times 10^6$ $B\overline{B}$ pairs collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. The peak near the threshold in the $D^0\overline{D}{}^{*0}$ invariant mass spectrum is fitted using a relativistic Breit-Wigner lineshape. We determine the mass and width parameters to be $m = 3873.71 ^{+0.56}_{-0.50} ({\rm stat}) \pm0.13 ({\rm syst}) ~{\rm MeV}/c^2$ and $\Gamma_0 = 5.2 ^{+2.2}_{-1.5} ({\rm stat}) \pm 0.4 ({\rm syst})~{\rm MeV}$, respectively. The branching fraction is found to be ${\cal B} (B^+\to X(3872)K^+) \times {\cal{B}}(X(3872) \to D^0\overline{D}{}^{*0}) = (0.97 ^{+0.21}_{-0.18} ({\rm stat}) \pm 0.10 ({\rm syst})) \times 10^{-4}$. The signal from $B^0$ decays is observed for the first time with $5.2\sigma$ significance, and the ratio of branching fractions between charged and neutral $B$ decays is measured to be ${\cal B}(B^0\to X(3872)K^0)/{\cal B}(B^+ \to X(3872)K^+) = 1.34^{+0.47}_{-0.40} ({\rm stat}) ^{+0.10}_{-0.12} ({\rm syst})$. The peak is also studied using a Flatté lineshape. We determine the lower limit on the $D\overline{D}{}^{*}$ coupling constant $g$ to be $0.075$ at 95% credibility in the parameter region where the ratio of $g$ to the mass difference from the $D^0\overline{D}{}^{*0}$ threshold is equal to $-15.11~{\rm GeV}^{-1}$, as measured by LHCb.

We report measurements of the branching fraction and $\it CP$ asymmetry in $B^{0} \to \pi^{0} \pi^{0}$ decays reconstructed at Belle II in an electron-positron collision sample containing $198 \times 10^{6}$ $B\overline{B}$ pairs. We measure a branching fraction $\mathcal{B}(\Bpipi) = (1.38 \pm 0.27 \pm 0.22) \times 10^{-6}$ and a $\it CP$ asymmetry $\Acp(\Bpipi) = 0.14 \pm 0.46 \pm 0.07$, where the first uncertainty is statistical and the second is systematic.

precision sin 2 independent left-right asymmetry measurements of e + e − transitions to pairs of muons, taus, and b-quarks.

We present a study of rare decay modes $B^{+} \to D_{s}^{+}h^{0}$, $B^{+} \to D_{s}^{\ast+}h^{0}$, and $B^{+} \to D^{+}h^{0}$, where $h^{0}$ denotes the neutral mesons $\eta$ or $K^{0}$, using a data sample of $(772 \pm 10 ) \times 10^{6}$ $B\bar{B}$ events produced at the $\Upsilon(4S)$ resonance. The data were collected by the Belle detector operating at the asymmetric-energy KEKB collider. We observe no evidence for these decays, so we provide upper limits at the 90$\%$ confidence level on the branching fractions of $B^{+} \to D_{s}^{+}h^{0}$, $D_{s}^{\ast+}h^{0}$, and $D^{+}h^{0}$ decay modes. Along with rare decay modes, we report improved measurements of the color-suppressed decay branching fractions $\mathcal{B}(\bar{B}^{0} \to D^{0}\eta)$ = (26.6 $\pm$ 1.2 $\pm$ 2.1) $\times$ $10^{-5}$ and $\mathcal{B}(\bar{B}^{0} \to D^{0}\bar{K}^{0})$ = (5.6 $\pm$ 0.5 $\pm$ 0.2) $\times$ $10^{-5}$. The first and second uncertainties are statistical and systematic, respectively.

Belle II Collaboration: I. Adachi, K. Adamczyk, L. Aggarwal, H. Ahmed, H. Aihara, N. Akopov, A. Aloisio, N. Anh Ky, D. M. Asner, T. Aushev, V. Aushev, H. Bae, S. Bahinipati, P. Bambade, Sw. Banerjee, J. Baudot, M. Bauer, A. Baur, A. Beaubien, J. Becker, P. K. Behera, J. V. Bennett, E. Bernieri, F. U. Bernlochner, V. Bertacchi, M. Bertemes, E. Bertholet, M. Bessner, S. Bettarini, B. Bhuyan, F. Bianchi, T. Bilka, D. Biswas, D. Bodrov, A. Bolz, J. Borah, A. Bozek, M. Bračko, P. Branchini, T. E. Browder, A. Budano, S. Bussino, M. Campajola, L. Cao, G. Casarosa, C. Cecchi, M.-C. Chang, P. Chang, R. Cheaib, P. Cheema, V. Chekelian, C. Chen, Y. Q. Chen, B. G. Cheon, K. Chilikin, K. Chirapatpimol, H.-E. Cho, K. Cho, S.-J. Cho, S.-K. Choi, S. Choudhury, D. Cinabro, L. Corona, S. Cunliffe, S. Das, F. Dattola, E. De La Cruz-Burelo, S. A. De La Motte, G. De Nardo, M. De Nuccio, G. De Pietro, R. de Sangro, M. Destefanis, S. Dey, A. De Yta-Hernandez, R. Dhamija, A. Di Canto, F. Di Capua, J. Dingfelder, Z. Doležal, I. Domínguez Jiménez, T. V. Dong, M. Dorigo, K. Dort, D. Dossett, S. Dreyer, S. Dubey, G. Dujany, P. Ecker, M. Eliachevitch, D. Epifanov, P. Feichtinger, T. Ferber, D. Ferlewicz, T. Fillinger, C. Finck, G. Finocchiaro, A. Fodor, F. Forti, B. G. Fulsom, E. Ganiev, M. Garcia-Hernandez, V. Gaur, A. Gaz, A. Gellrich, G. Ghevondyan, R. Giordano, A. Giri, A. Glazov, B. Gobbo, R. Godang, P. Goldenzweig, S. Granderath, E. Graziani, D. Greenwald, Z. Gruberová, T. Gu, K. Gudkova, J. Guilliams, H. Haigh, T. Hara, K. Hayasaka, H. Hayashii, S. Hazra, C. Hearty, I. Heredia de la Cruz, M. Hernández Villanueva, A. Hershenhorn, T. Higuchi, E. C. Hill, M. Hohmann, C.-L. Hsu, T. Iijima, K. Inami, G. Inguglia, N. Ipsita, A. Ishikawa, S. Ito, R. Itoh, M. Iwasaki, P. Jackson, W. W. Jacobs, D. E. Jaffe, E.-J. Jang, Q. P. Ji, S. Jia, Y. Jin, K. K. Joo, H. Junkerkalefeld, H. Kakuno, A. B. Kaliyar, K. H. Kang, S. Kang, R. Karl, G. Karyan, C. Kiesling, C.-H. Kim, D. Y. Kim, K.-H. Kim, Y.-K. Kim, H. Kindo, K. Kinoshita, P. Kodyš, T. Koga, S. Kohani, K. Kojima, T. Konno, A. Korobov, S. Korpar, E. Kovalenko, R. Kowalewski, T. M. G. Kraetzschmar, P. Križan, P. Krokovny, T. Kuhr, J. Kumar, K. Kumara, T. Kunigo, A. Kuzmin, Y.-J. Kwon, S. Lacaprara, T. Lam, L. Lanceri, J. S. Lange, M. Laurenza, K. Lautenbach, R. Leboucher, F. R. Le Diberder, P. Leitl, C. Li, L. K. Li, J. Libby, K. Lieret, Z. Liptak, Q. Y. Liu, D. Liventsev, S. Longo, A. Lozar, T. Lueck, T. Luo, C. Lyu, M. Maggiora, R. Maiti, S. Maity, R. Manfredi, E. Manoni, S. Marcello, C. Marinas, L. Martel, A. Martini, T. Martinov, L. Massaccesi, M. Masuda, K. Matsuoka, D. Matvienko, S. K. Maurya, J. A. McKenna, F. Meier, M. Merola, F. Metzner, M. Milesi, C. Miller, K. Miyabayashi, R. Mizuk, G. B. Mohanty, N. Molina-Gonzalez, S. Moneta, H.-G. Moser, M. Mrvar, R. Mussa, I. Nakamura, K. R. Nakamura, M. Nakao, H. Nakayama, Y. Nakazawa, A. Narimani Charan, M. Naruki, Z. Natkaniec, A. Natochii, L. Nayak, M. Nayak, G. Nazaryan, N. K. Nisar, S. Nishida, S. Ogawa, H. Ono, Y. Onuki, P. Oskin, P. Pakhlov, G. Pakhlova, A. Paladino, A. Panta, E. Paoloni, S. Pardi, K. Parham, H. Park, S.-H. Park, B. Paschen, A. Passeri, S. Patra, S. Paul, T. K. Pedlar, I. Peruzzi, R. Peschke, R. Pestotnik, M. Piccolo, L. E. Piilonen, G. Pinna Angioni, P. L. M. Podesta-Lerma, T. Podobnik, S. Pokharel, L. Polat, C. Praz, S. Prell, E. Prencipe, M. T. Prim, H. Purwar, N. Rad, P. Rados, G. Raeuber, S. Raiz, A. Ramirez Morales, M. Reif, S. Reiter, M. Remnev, I. Ripp-Baudot, G. Rizzo, S. H. Robertson, D. Rodríguez Pérez, J. M. Roney, A. Rostomyan, N. Rout, G. Russo, D. A. Sanders, S. Sandilya, A. Sangal, L. Santelj, Y. Sato, V. Savinov, B. Scavino, J. Schueler, C. Schwanda, Y. Seino, A. Selce, K. Senyo, J. Serrano, M. E. Sevior, C. Sfienti, C. P. Shen, T. Shillington, J.-G. Shiu, A. Sibidanov, F. Simon, J. B. Singh, J. Skorupa, R. J. Sobie, A. Soffer, A. Sokolov, E. Solovieva, S. Spataro, B. Spruck, M. Starič, S. Stefkova, Z. S. Stottler, R. Stroili, J. Strube, Y. Sue, M. Sumihama, K. Sumisawa, W. Sutcliffe, S. Y. Suzuki, H. Svidras, M. Takizawa, U. Tamponi, K. Tanida, H. Tanigawa, N. Taniguchi, F. Tenchini, A. Thaller, R. Tiwary, D. Tonelli, E. Torassa, N. Toutounji, K. Trabelsi, M. Uchida, I. Ueda, Y. Uematsu, T. Uglov, K. Unger, Y. Unno, K. Uno, S. Uno, Y. Ushiroda, S. E. Vahsen, R. van Tonder, K. E. Varvell, A. Vinokurova, L. Vitale, V. Vobbilisetti, H. M. Wakeling, E. Wang, M.-Z. Wang, X. L. Wang, A. Warburton, M. Watanabe, S. Watanuki, M. Welsch, C. Wessel, X. P. Xu, B. D. Yabsley, S. Yamada, W. Yan, S. B. Yang, H. Ye, J. H. Yin, Y. M. Yook, K. Yoshihara, C. Z. Yuan, Y. Yusa, L. Zani, Y. Zhang, V. Zhilich, Q. D. Zhou, X. Y. Zhou, V. I. Zhukova, R. Žlebčík

We present the first search for the weak radiative decays $\Lambda_c^+ \to \Sigma^+ \gamma$ and $\Xi_c^0 \to \Xi^0 \gamma$ using a data sample of 980~fb$^{-1}$ collected by the Belle detector operating at the KEKB asymmetric-energy $e^+e^-$ collider. There are no evident $\Lambda_c^+ \to \Sigma^+ \gamma$ or $\Xi_c^0 \to \Xi^0 \gamma$ signals. Taking the decays $\Lambda_c^+ \to p K^- \pi^+$ and $\Xi_c^0 \to \Xi^- \pi^+$ as normalization channels, the upper limits at 90\% credibility level on the ratios of branching fractions ${\cal B}(\Lambda_c^+ \to \Sigma^+ \gamma)/{\cal B}(\Lambda_c^+ \to p K^{-} \pi^+)<4.0 \times 10^{-3}$ and ${\cal B}(\Xi_c^0 \to \Xi^0 \gamma)/{\cal B}(\Xi_c^0 \to \Xi^- \pi^+)<1.2 \times 10^{-2}$ are determined. We obtain the upper limits at 90\% credibility level on the absolute branching fractions ${\cal B}(\Lambda_c^+ \to \Sigma^+ \gamma)<2.6 \times 10^{-4}$ and ${\cal B}(\Xi_c^0 \to \Xi^0 \gamma)<1.8 \times 10^{-4}$.

A dark leptophilic scalar $(\phi_L)$ is a hypothetical particle from the dark sector, that couples only to leptons rather than quarks. In the \mev to the \gev range, such particles are weakly constrained by direct detection experiments. We report on a search for $\phi_L$ in $e^+e^- \to \tau^+ \tau^- \phi_L, ~\phi_L \to \ell^+ \ell^- ~(\ell = e, \mu)$ process using 626 fb$^{-1}$ of data collected by the Belle experiment near the $\Upsilon(4S)$ resonance. We validate the backgrounds with multiple control regions in data, using a novel multiclass multivariate event classifier. In absence of signal in the $\phi_L$ mass range $0.04~Gev \leq m_{\phi_{L}} \leq 6.5~Gev$, we quote frequentist limits on the coupling between $\phi_L$ and leptons, where nuisance parameters describing the systematic variations are obtained from data. Our bounds, obtained in a blinded approach, are comparable to the Bayesian limits obtained by the BABAR experiment, and exclude the parameter space below $4~GeV$ favored by measurement of the anomalous magnetic moment of the muon.

K.-N. Chu , Y.-R. Lin , M.-Z. Wang , I. Adachi , K. Adamczyk , H. Aihara , S. Al Said , D. M. Asner , H. Atmacan , V. Aulchenko , T. Aushev , R. Ayad , V. Babu , Sw. Banerjee , P. Behera , K. Belous , J. Bennett , M. Bessner , V. Bhardwaj , B. Bhuyan , T. Bilka , D. Biswas , D. Bodrov , G. Bonvicini , J. Borah , A. Bozek , M. Bračko , P. Branchini , T. E. Browder , A. Budano , M. Campajola , D. Červenkov , M.-C. Chang , P. Chang , A. Chen , B. G. Cheon , K. Chilikin , H. E. Cho , K. Cho , S.-J. Cho , S.-K. Choi , Y. Choi , S. Choudhury , D. Cinabro , G. De Nardo , G. De Pietro , R. Dhamija , F. Di Capua , J. Dingfelder , Z. Doležal , T. V. Dong , D. Epifanov , T. Ferber , D. Ferlewicz , B. G. Fulsom , V. Gaur , A. Garmash , A. Giri , P. Goldenzweig , B. Golob , E. Graziani , T. Gu , K. Gudkova , C. Hadjivasiliou , S. Halder , X. Han , K. Hayasaka , H. Hayashii , W.-S. Hou , C.-L. Hsu , K. Huang , T. Iijima , K. Inami , N. Ipsita , A. Ishikawa , R. Itoh , M. Iwasaki , W. W. Jacobs , E.-J. Jang , Y. Jin , K. K. Joo , D. Kalita , A. B. Kaliyar , T. Kawasaki , C. Kiesling , C. H. Kim , D. Y. Kim , K.-H. Kim , Y.-K. Kim , P. Kodyš , T. Konno , A. Korobov , S. Korpar , E. Kovalenko , P. Križan , P. Krokovny , T. Kuhr , R. Kumar , K. Kumara , A. Kuzmin , Y.-J. Kwon , Y.-T. Lai , T. Lam , J. S. Lange , S. C. Lee , C. H. Li , J. Li , L. K. Li , S. X. Li , Y. Li , Y. B. Li , L. Li Gioi , J. Libby , K. Lieret , D. Liventsev , T. Luo , M. Masuda , T. Matsuda , D. Matvienko , S. K. Maurya , F. Meier , M. Merola , F. Metzner , K. Miyabayashi , R. Mizuk , G. B. Mohanty , I. Nakamura , M. Nakao , Z. Natkaniec , A. Natochii , L. Nayak , N. K. Nisar , S. Nishida , Y. Onuki , P. Oskin , P. Pakhlov , G. Pakhlova , S. Pardi , H. Park , J. Park , A. Passeri , S. Paul , T. K. Pedlar , R. Pestotnik , L. E. Piilonen , T. Podobnik , E. Prencipe , M. T. Prim , A. Rostomyan , N. Rout , G. Russo , S. Sandilya , L. Santelj , V. Savinov , G. Schnell , C. Schwanda , Y. Seino , K. Senyo , M. E. Sevior , W. Shan , M. Shapkin , C. Sharma , C. P. Shen , J.-G. Shiu , B. Shwartz , F. Simon , A. Sokolov , E. Solovieva , M. Starič , Z. S. Stottler , J. F. Strube , M. Sumihama , K. Sumisawa , T. Sumiyoshi , M. Takizawa , U. Tamponi , K. Tanida , F. Tenchini , K. Trabelsi , M. Uchida , T. Uglov , Y. Unno , S. Uno , P. Urquijo , Y. Usov , S. E. Vahsen , R. van Tonder , G. Varner , K. E. Varvell , A. Vinokurova , A. Vossen , S. Watanuki , E. Won , X. Xu , B. D. Yabsley , W. Yan , S. B. Yang , J. Yelton , J. H. Yin , C. Z. Yuan , L. Yuan , Y. Yusa , Z. P. Zhang , V. Zhilich , and V. Zhukova (The Belle Collaboration)

T. Czank, ∗ I. Jaegle, 85, † A. Ishikawa, 15 I. Adachi, 15 K. Adamczyk, H. Aihara, D. M. Asner, T. Aushev, R. Ayad, V. Babu, S. Bahinipati, P. Behera, J. Bennett, F. Bernlochner, M. Bessner, V. Bhardwaj, B. Bhuyan, T. Bilka, J. Biswal, A. Bobrov, 67 G. Bonvicini, A. Bozek, M. Bračko, T. E. Browder, M. Campajola, 58 L. Cao, D. Červenkov, M.-C. Chang, A. Chen, B. G. Cheon, K. Chilikin, H. E. Cho, K. Cho, Y. Choi, S. Choudhury, D. Cinabro, S. Das, N. Dash, G. De Nardo, 58 R. Dhamija, F. Di Capua, 58 Z. Doležal, T. V. Dong, S. Eidelman, 67, 45 T. Ferber, D. Ferlewicz, B. G. Fulsom, R. Garg, V. Gaur, A. Garmash, 67 A. Giri, P. Goldenzweig, B. Golob, 36 O. Grzymkowska, Y. Guan, K. Gudkova, 67 C. Hadjivasiliou, O. Hartbrich, K. Hayasaka, H. Hayashii, M. T. Hedges, M. Hernandez Villanueva, T. Higuchi, W.-S. Hou, C.-L. Hsu, T. Iijima, 56 K. Inami, G. Inguglia, R. Itoh, 15 M. Iwasaki, Y. Iwasaki, W. W. Jacobs, E.-J. Jang, S. Jia, Y. Jin, C. W. Joo, K. K. Joo, K. H. Kang, G. Karyan, T. Kawasaki, H. Kichimi, C. Kiesling, B. H. Kim, C. H. Kim, D. Y. Kim, K.-H. Kim, S. H. Kim, Y.-K. Kim, P. Kodyš, I. Komarov, T. Konno, A. Korobov, 67 S. Korpar, E. Kovalenko, 67 P. Križan, 36 R. Kroeger, P. Krokovny, 67 T. Kuhr, M. Kumar, K. Kumara, Y.-J. Kwon, Y.-T. Lai, J. S. Lange, I. S. Lee, S. C. Lee, Y. B. Li, L. Li Gioi, J. Libby, K. Lieret, D. Liventsev, 19 T. Luo, C. MacQueen, M. Masuda, 73 T. Matsuda, D. Matvienko, 67, 45 M. Merola, 58 F. Metzner, K. Miyabayashi, R. Mizuk, 21 G. B. Mohanty, S. Mohanty, 91 T. Mori, M. Mrvar, R. Mussa, M. Nakao, 15 Z. Natkaniec, A. Natochii, L. Nayak, M. Niiyama, N. K. Nisar, S. Nishida, 15 H. Ono, 65 Y. Onuki, P. Pakhlov, 55 G. Pakhlova, 45 T. Pang, S. Pardi, H. Park, S.-H. Park, S. Patra, S. Paul, 51 T. K. Pedlar, R. Pestotnik, L. E. Piilonen, T. Podobnik, 36 V. Popov, E. Prencipe, M. T. Prim, M. Röhrken, A. Rostomyan, N. Rout, G. Russo, D. Sahoo, S. Sandilya, A. Sangal, L. Santelj, 36 T. Sanuki, V. Savinov, G. Schnell, 23 J. Schueler, C. Schwanda, Y. Seino, K. Senyo, M. E. Sevior, M. Shapkin, C. Sharma, V. Shebalin, C. P. Shen, J.-G. Shiu, B. Shwartz, 67 A. Sokolov, E. Solovieva, S. Stanič, M. Starič, Z. S. Stottler, M. Sumihama, T. Sumiyoshi, W. Sutcliffe, M. Takizawa, 20, 74 K. Tanida, Y. Tao, F. Tenchini, K. Trabelsi, M. Uchida, S. Uehara, 15 T. Uglov, 21 K. Uno, S. Uno, 15 P. Urquijo, R. Van Tonder, G. Varner, A. Vossen, C. H. Wang, E. Wang, M.-Z. Wang, P. Wang, S. Watanuki, E. Won, X. Xu, B. D. Yabsley, H. Yamamoto, W. Yan, S. B. Yang, H. Ye, J. Yelton, J. H. Yin, Y. Yusa, Z. P. Zhang, V. Zhilich, 67 V. Zhukova, and V. Zhulanov 67

We present the first observation of the Ω 0 c → Ω − µ + ν µ decay and present measurements of the branching fraction ratios of the Ω 0 c → Ω − ℓ + ν ℓ decays compared to the reference mode Ω 0 c → Ω − π + , ( ℓ = e or µ ). This analysis is based on 89.5 fb − 1 , 711 fb − 1 , and 121.1 fb − 1 data samples collected with the Belle detector at the KEKB asymmetric-energy e + e − collider at the center-of-mass energies of 10.52 GeV, 10.58 GeV, and 10.86 GeV, respectively. The Ω 0 c signal yields are extracted by fitting M Ω ℓ and M Ω π spectra. The branching fraction ratios B (Ω 0 c → Ω − e + ν e ) / B (Ω 0 c → Ω − π + ) and B (Ω 0 c → Ω − µ + ν µ ) / B (Ω 0 c → Ω − π + ) are measured to be 1 . 98 ± 0 . 13 (stat . ) ± 0 . 08 (syst . ) and 1 . 94 ± 0 . 18 (stat . ) ± 0 . 10 (syst . ), respectively. The ratio of B (Ω 0 c → Ω − e + ν e ) / B (Ω 0 c → Ω − µ + ν µ ) is measured to be 1 . 02 ± 0 . 10 (stat . ) ± 0 . 02 (syst . ), which is consistent with the expectation of lepton flavor universality.

E. Kovalenko , A. Garmash, P. Krokovny, I. Adachi, H. Aihara, D. M. Asner, V. Aulchenko, T. Aushev, R. Ayad, V. Babu, S. Bahinipati, P. Behera, J. Bennett, M. Bessner, T. Bilka, J. Biswal, A. Bobrov, A. Bondar, G. Bonvicini, A. Bozek, M. Bračko, T. E. Browder, M. Campajola, L. Cao, D. Červenkov, M.-C. Chang, B. G. Cheon, K. Chilikin, H. E. Cho, K. Cho, S.-J. Cho, S.-K. Choi, Y. Choi, S. Choudhury, D. Cinabro, S. Cunliffe, S. Das, G. De Nardo, F. Di Capua, Z. Doležal, T. V. Dong, S. Eidelman, D. Epifanov, T. Ferber, A. Frey, B. G. Fulsom, R. Garg, V. Gaur, N. Gabyshev, A. Giri, P. Goldenzweig, D. Greenwald, K. Gudkova, C. Hadjivasiliou, T. Hara, K. Hayasaka, W.-S. Hou, C.-L. Hsu, T. Iijima, K. Inami, A. Ishikawa, R. Itoh, M. Iwasaki, W.W. Jacobs, Y. Jin, K. K. Joo, G. Karyan, H. Kichimi, C. Kiesling, C. H. Kim, D. Y. Kim, K.-H. Kim, S. H. Kim, Y.-K. Kim, K. Kinoshita, P. Kodyš, T. Konno, A. Korobov, S. Korpar, P. Križan, R. Kroeger, T. Kuhr, M. Kumar, R. Kumar, K. Kumara, A. Kuzmin, Y.-J. Kwon, K. Lalwani, J. S. Lange, S. C. Lee, Y. B. Li, L. Li Gioi, J. Libby, K. Lieret, D. Liventsev, C. MacQueen, M. Masuda, T. Matsuda, D. Matvienko, M. Merola, F. Metzner, K. Miyabayashi, R. Mizuk, G. B. Mohanty, M. Nakao, A. Natochii, L. Nayak, M. Niiyama, N. K. Nisar, S. Nishida, K. Ogawa, S. Ogawa, H. Ono, P. Oskin, P. Pakhlov, G. Pakhlova, S. Pardi, H. Park, S.-H. Park, S. Patra, S. Paul, T. K. Pedlar, R. Pestotnik, L. E. Piilonen, T. Podobnik, E. Prencipe, M. T. Prim, A. Rabusov, M. Röhrken, A. Rostomyan, N. Rout, G. Russo, D. Sahoo, Y. Sakai, S. Sandilya, A. Sangal, T. Sanuki, V. Savinov, G. Schnell, C. Schwanda, Y. Seino, K. Senyo, M. E. Sevior, C. Sharma, J.-G. Shiu, B. Shwartz, A. Sokolov, E. Solovieva, M. Starič, Z. S. Stottler, M. Sumihama, T. Sumiyoshi, W. Sutcliffe, M. Takizawa, U. Tamponi, K. Tanida, F. Tenchini, K. Trabelsi, M. Uchida, T. Uglov, Y. Unno, K. Uno, S. Uno, P. Urquijo, Y. Usov, R. Van Tonder, G. Varner, A. Vinokurova, E. Waheed, C. H. Wang, M.-Z. Wang, P. Wang, M. Watanabe, O. Werbycka, E. Won, W. Yan, S. B. Yang, H. Ye, J. H. Yin, Y. Yusa, Z. P. Zhang, V. Zhilich, and V. Zhukova

Using a data sample of 980 fb − 1 collected with the Belle detector operating at the KEKB asymmetric-energy e þ e − collider, we present evidence for the Ω ð 2012 Þ − in the resonant substructure of Ω 0 c → π þ ð ¯ K Ξ Þ − ( ð ¯ K Ξ Þ − ¼ K − Ξ 0 þ ¯ K 0 Ξ − ) decays. The significance of the Ω ð 2012 Þ − signal is 4 . 2 σ after considering the systematic uncertainties. The ratio of the branching fraction of Ω 0 c → π þ Ω ð 2012 Þ − → π þ ð ¯ K Ξ Þ − relative to that of Ω 0 c → π þ Ω − is calculated to be 0 . 220 (cid:2) 0 . 059 ð stat : Þ (cid:2) 0 . 035 ð syst : Þ . The individual ratios of the branching fractions of the two isospin modes are also determined and found to be B ð Ω 0 c → π þ Ω ð 2012 Þ − Þ × = K 6 (cid:2) 3 . ð stat : 1 . 8 % and B Ω → Ω ð 2012 Þ − × ð 2012 Þ − K Þ = B Ω K Ξ − Þ ¼ . 5 2 . 8 ð stat : Þ . 7 ð syst : ÞÞ % .