Measurement of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>B</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:mo>/</mml:mo><mml:msup><mml:mi>B</mml:mi><mml:mn>0</mml:mn></mml:msup></mml:math> production ratio in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>e</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:msup><mml:mi>e</mml:mi><mml:mo>−</mml:mo></mml:msup></mml:math> collisions at the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="normal">ϒ</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:mn>4</mml:mn><mml:mi>S</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:math> resonance using <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>B</mml:mi><mml:mo stretchy="false">→</mml:mo><mml:mi>J</mml:mi><mml:mo>/</mml:mo><mml:mi>ψ</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:mo>ℓ</mml:mo><mml:mo>ℓ</mml:mo><mml:mo stretchy="false">)</mml:mo><mml:mi>K</mml:mi></mml:math> decays at Belle
S. Choudhury, S. Sandilya, K. Trabelsi, A. Giri, I. Adachi, H. Aihara, D. M. Asner, H. Atmacan, T. Aushev, R. Ayad, V. Babu, S. Bahinipati, P. K. Behera, K. Belous, J. V. Bennett, M. Bessner, V. Bhardwaj, B. Bhuyan, T. Bilka, D. Bodrov, G. Bonvicini, J. Borah, A. Bożek, M. Bračko, P. Branchini, T. E. Browder, A. Budano, M. Campajola, D. Červenkov, M.-C. Chang, C. Chen, B. G. Cheon, K. Chilikin, H.-E. Cho, K. Cho, S.-J. Cho, S.-K. Choi, Y. Choi, D. Cinabro, S. Das, G. De Pietro, F. Di Capua, J. Dingfelder, Z. Doležal, T. V. Dong, D. Epifanov, D. Ferlewicz, B. G. Fulsom, R. Garg, V. Gaur, N. Gabyshev, P. Goldenzweig, E. Graziani, T. Gu, K. Gudkova, C. Hadjivasiliou, T. Hara, K. Hayasaka, H. Hayashii, M. T. Hedges, D. Herrmann, W.-S. Hou, C.-L. Hsu, K. Inami, N. Ipsita, A. Ishikawa, R. Itoh, M. Iwasaki, W. W. Jacobs, E.-J. Jang, Q. P. Ji, S. Jia, Y. Jin, K. K. Joo, K. H. Kang, T. Kawasaki, C. Kiesling, C. H. Kim, D. Y. Kim, K.-H. Kim, Y.-K. Kim, H. Kindo, K. Kinoshita, P. Kodyš, T. Konno, A. Korobov, S. Korpar, E. Kovalenko, P. Križan, P. Krokovny, M. Kumar, R. Kumar, K. Kumara, Y.-J. Kwon, T. Lam, J. S. Lange, M. Laurenza, S. C. Lee, P. Lewis, Jin Li
Abstract
We measure the ratio of branching fractions for the $\mathrm{\ensuremath{\Upsilon}}(4S)$ decays to ${B}^{+}{B}^{\ensuremath{-}}$ and ${B}^{0}{\overline{B}}^{0}$ using ${B}^{+}\ensuremath{\rightarrow}J/\ensuremath{\psi}(\ensuremath{\ell}\ensuremath{\ell}){K}^{+}$ and ${B}^{0}\ensuremath{\rightarrow}J/\ensuremath{\psi}(\ensuremath{\ell}\ensuremath{\ell}){K}^{0}$ samples, where $J/\ensuremath{\psi}(\ensuremath{\ell}\ensuremath{\ell})$ stands for $J/\ensuremath{\psi}\ensuremath{\rightarrow}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ ($\ensuremath{\ell}=e$ or $\ensuremath{\mu}$), with $711\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of data collected at the $\mathrm{\ensuremath{\Upsilon}}(4S)$ resonance with the Belle detector. We find the decay rate ratio of $\mathrm{\ensuremath{\Upsilon}}(4S)\ensuremath{\rightarrow}{B}^{+}{B}^{\ensuremath{-}}$ over $\mathrm{\ensuremath{\Upsilon}}(4S)\ensuremath{\rightarrow}{B}^{0}{\overline{B}}^{0}$ to be $1.065\ifmmode\pm\else\textpm\fi{}0.012\ifmmode\pm\else\textpm\fi{}0.019\ifmmode\pm\else\textpm\fi{}0.047$, which is the most precise measurement to date. The first and second uncertainties are statistical and systematic, respectively, and the third uncertainty is due to the assumption of isospin symmetry in $B\ensuremath{\rightarrow}J/\ensuremath{\psi}(\ensuremath{\ell}\ensuremath{\ell})K$.