학술논문
Test of lepton flavor universality and search for lepton flavor violation in $B \to K \ell\ell$ decays
Document Type
Working Paper
Author
Choudhury, S.; Sandilya, S.; Trabelsi, K.; Giri, A.; Aihara, H.; Said, S. Al; Asner, D. M.; Atmacan, H.; Aulchenko, V.; Aushev, T.; Ayad, R.; Babu, V.; Bahinipati, S.; Behera, P.; Beleño, C.; Belous, K.; Bennett, J.; Bernlochner, F.; Bessner, M.; Bhardwaj, V.; Bilka, T.; Biswal, J.; Bonvicini, G.; Bozek, A.; Bračko, M.; Browder, T. E.; Campajola, M.; Červenkov, D.; Chang, M. -C.; Chang, P.; Chekelian, V.; Chen, A.; Cheon, B. G.; Chilikin, K.; Cho, K.; Choi, S. -K.; Choi, Y.; Cinabro, D.; Cunliffe, S.; Dash, N.; De Nardo, G.; Dhamija, R.; Di Capua, F.; Dingfelder, J.; Doležal, Z.; Dong, T. V.; Dossett, D.; Dubey, S.; Eidelman, S.; Epifanov, D.; Ferber, T.; Ferlewicz, D.; Fulsom, B. G.; Garg, R.; Gaur, V.; Gabyshev, N.; Garmash, A.; Goldenzweig, P.; Golob, B.; Greenwald, D.; Hadjivasiliou, C.; Hartbrich, O.; Hayashii, H.; Hedges, M. T.; Villanueva, M. Hernandez; Higuchi, T.; Hou, W. -S.; Hsu, C. -L.; Iijima, T.; Inami, K.; Ishikawa, A.; Itoh, R.; Iwasaki, M.; Iwasaki, Y.; Jacobs, W. W.; Jang, E. -J.; Jeon, H. B.; Jia, S.; Jin, Y.; Joo, C. W.; Joo, K. K.; Kahn, J.; Kaliyar, A. B.; Kang, K. H.; Karyan, G.; Kichimi, H.; Kiesling, C.; Kim, B. H.; Kim, D. Y.; Kim, K. -H.; Kim, K. T.; Kim, S. H.; Kim, Y. -K.; Kinoshita, K.; Kodyš, P.; Korpar, S.; Kotchetkov, D.; Križan, P.; Kroeger, R.; Krokovny, P.; Kuhr, T.; Kulasiri, R.; Kumar, R.; Kumara, K.; Kuzmin, A.; Kwon, Y. -J.; Lalwani, K.; Lee, S. C.; Lewis, P.; Li, C. H.; Li, L. K.; Li, Y. B.; Gioi, L. Li; Libby, J.; Lieret, K.; Liptak, Z.; Liventsev, D.; Luo, T.; Masuda, M.; Matsuda, T.; Matvienko, D.; Merola, M.; Miyabayashi, K.; Mizuk, R.; Mohanty, G. B.; Mohanty, S.; Moon, T. J.; Mori, T.; Nakamura, I.; Nakamura, K. R.; Nakao, M.; Natkaniec, Z.; Natochii, A.; Nayak, L.; Nayak, M.; Niiyama, M.; Nisar, N. K.; Nishida, S.; Ogawa, K.; Ono, H.; Onuki, Y.; Oskin, P.; Pakhlov, P.; Pakhlova, G.; Pardi, S.; Park, H.; Park, S. -H.; Patra, S.; Paul, S.; Pedlar, T. K.; Pestotnik, R.; Piilonen, L. E.; Podobnik, T.; Popov, V.; Prencipe, E.; Prim, M. T.; Rabusov, A.; Rostomyan, A.; Rout, N.; Rozanska, M.; Russo, G.; Sahoo, D.; Sakai, Y.; Santelj, L.; Sanuki, T.; Savinov, V.; Schnell, G.; Schueler, J.; Schwanda, C.; Schwartz, A. J.; Seino, Y.; Senyo, K.; Sevior, M. E.; Shapkin, M.; Shebalin, V.; Shiu, J. -G.; Shwartz, B.; Simon, F.; Sokolov, A.; Solovieva, E.; Stanič, S.; Starič, M.; Stottler, Z. S.; Sumiyoshi, T.; Sutcliffe, W.; Takizawa, M.; Tamponi, U.; Tanida, K.; Tenchini, F.; Uchida, M.; Uehara, S.; Uglov, T.; Unno, Y.; Uno, S.; Urquijo, P.; Ushiroda, Y.; Van Tonder, R.; Varner, G.; Varvell, K. E.; Vinokurova, A.; Vorobyev, V.; Waheed, E.; Wang, C. H.; Wang, E.; Wang, M. -Z.; Wang, P.; Watanabe, M.; Watanuki, S.; Wehle, S.; Wiechczynski, J.; Won, E.; Xu, X.; Yabsley, B. D.; Yan, W.; Yang, S. B.; Ye, H.; Yelton, J.; Yin, J. H.; Yuan, C. Z.; Yusa, Y.; Zhang, Z. P.; Zhilich, V.; Zhukova, V.
Source
JHEP 03 (2021) 105
Subject
Language
Abstract
We present measurements of the branching fractions for the decays $B\to K \mu^{+}\mu^{-}$ and $B\to K e^{+}e^{-}$, and their ratio ($R_{K}$), using a data sample of 711 $fb^{-1}$ that contains $772 \times 10^{6}$ $B\bar{B}$ events. The data were collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. The ratio $R_{K}$ is measured in five bins of dilepton invariant-mass-squared ($q^{2}$): $q^{2} \in (0.1, 4.0), (4.0, 8.12), (1.0, 6.0)$, $(10.2, 12.8)$ and ($>14.18) GeV^{2}/c^{4}$, along with the whole $q^2$ region. The $R_{K}$ value for $q^{2} \in (1.0, 6.0) GeV^{2}/c^{4}$ is $1.03^{+0.28}_{-0.24} \pm 0.01$. The first and second uncertainties listed are statistical and systematic, respectively. All results for $R_{K}$ are consistent with Standard Model predictions. We also measure $C\!P$-averaged isospin asymmetries in the same $q^{2}$ bins. The results are consistent with a null asymmetry, with the largest difference of 2.6 standard deviations occurring for the $q^{2}\in(1.0,6.0) GeV^{2}/c^{4}$ bin in the mode with muon final states. The measured differential branching fractions, ${d\cal B}/{dq^{2}}$, are consistent with theoretical predictions for charged $B$ decays, while the corresponding values are below the expectations for neutral $B$ decays. We have also searched for lepton-flavor-violating $B \rightarrow K\mu^{\pm}e^{\mp}$ decays and set $90\%$ confidence-level upper limits on the branching fraction in the range of $10^{-8}$ for $B^{+} \rightarrow K^{+}\mu^{\pm}e^{\mp}$, and $B^{0} \rightarrow K^{0}\mu^{\pm}e^{\mp}$ modes.
Comment: 18 pages, 7 figures
Comment: 18 pages, 7 figures