학술논문
Measurement of the Ratio of Partial Branching Fractions of Inclusive $\overline{B} \to X_u \ell \overline{\nu}$ to $\overline{B} \to X_{c} \ell \overline{\nu}$ and the Ratio of their Spectra with Hadronic Tagging
Document Type
Working Paper
Author
Belle Collaboration; Hohmann, M.; Urquijo, P.; Adachi, I.; Aihara, H.; Asner, D. M.; Aushev, T.; Ayad, R.; Babu, V.; Banerjee, Sw.; Bauer, M.; Bennett, J.; Bernlochner, F.; Bessner, M.; Bhuyan, B.; Bilka, T.; Biswas, D.; Bobrov, A.; Bodrov, D.; Bonvicini, G.; Borah, J.; Bozek, A.; Bračko, M.; Branchini, P.; Browder, T. E.; Budano, A.; Campajola, M.; Cao, L.; Chang, M. -C.; Cheon, B. G.; Cho, K.; Choi, S. -K.; Choi, Y.; Das, S.; Dash, N.; De Nardo, G.; De Pietro, G.; Dhamija, R.; Dingfelder, J.; Doležal, Z.; Dong, T. V.; Dubey, S.; Ecker, P.; Ferber, T.; Ferlewicz, D.; Frey, A.; Fulsom, B. G.; Gaur, V.; Giri, A.; Goldenzweig, P.; Graziani, E.; Gu, T.; Gudkova, K.; Hadjivasiliou, C.; Hartbrich, O.; Hayasaka, K.; Hayashii, H.; Hazra, S.; Hedges, M. T.; Herrmann, D.; Hou, W. -S.; Hsu, C. -L.; Inami, K.; Ishikawa, A.; Itoh, R.; Iwasaki, M.; Jacobs, W. W.; Ji, Q. P.; Jia, S.; Jin, Y.; Kawasaki, T.; Kiesling, C.; Kim, D. Y.; Kim, K. -H.; Kim, Y. -K.; Kinoshita, K.; Korobov, A.; Kovalenko, E.; Križan, P.; Kuhr, T.; Kumar, M.; Kumar, R.; Kumara, K.; Kwon, Y. -J.; Lam, T.; Laurenza, M.; Lee, S. C.; Levit, D.; Lewis, P.; Li, L. K.; Gioi, L. Li; Liventsev, D.; Masuda, M.; Matsuda, T.; Matvienko, D.; Maurya, S. K.; Meier, F.; Merola, M.; Metzner, F.; Mizuk, R.; Miyabayashi, K.; Mohanty, G. B.; Mussa, R.; Nakao, M.; Natkaniec, Z.; Natochii, A.; Nayak, L.; Nishida, S.; Ogawa, S.; Ono, H.; Oskin, P.; Pakhlova, G.; Pardi, S.; Park, H.; Park, J.; Park, S. -H.; Passeri, A.; Patra, S.; Paul, S.; Pedlar, T. K.; Pestotnik, R.; Piilonen, L. E.; Podobnik, T.; Prencipe, E.; Prim, M. T.; Röhrken, M.; Rozanska, M.; Russo, G.; Sandilya, S.; Savinov, V.; Schnell, G.; Schwanda, C.; Schwartz, A. J.; Seino, Y.; Senyo, K.; Shan, W.; Sharma, C.; Shiu, J. -G.; Shwartz, B.; Solovieva, E.; Starič, M.; Sumihama, M.; Sumisawa, K.; Takizawa, M.; Tanida, K.; Tenchini, F.; Trabelsi, K.; Uchida, M.; Uno, S.; Vahsen, S. E.; Varvell, K. E.; Vinokurova, A.; Wang, M. -Z.; Won, E.; Yabsley, B. D.; Yan, W.; Yang, S. B.; Yook, Y.; Zhilich, V.; Zhukova, V.
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Subject
Language
Abstract
We present a measurement of the ratio of partial branching fractions of the semi-leptonic inclusive decays, $\overline{B} \to X_{u} \ell \overline{\nu}$ to $\overline{B} \to X_{c} \ell \overline{\nu}$, where $\ell = (e, \mu)$, using the full Belle sample of $772 \times 10^{6}$ $B \kern 0.18em\overline{\kern -0.18em B}$ pairs collected at the $\Upsilon(4S)$ resonance. The ratio is measured via a two-dimensional fit to the squared four-momentum transfer to the lepton pair, and the charged lepton energy in the $B$ meson rest frame, where the latter must be larger than $1$ Ge\kern -0.1em V, covering approximately $86\%$ and $78\%$ of the $\overline{B} \to X_{u} \ell \overline{\nu}$ and $\overline{B} \to X_{c} \ell \overline{\nu}$ phase space, respectively. We find $\Delta \mathcal{B}(\overline{B} \to X_{u} \ell \overline{\nu})/ \Delta \mathcal{B}(\overline{B} \to X_{c} \ell \overline{\nu}) = 0.0196(1 \pm 8.4\%_{\rm stat} \pm 7.9\%_{\rm syst})$ where the uncertainties are statistical and systematic, respectively. In addition, we report the partial branching fractions separately for charged and neutral $B$ meson decays, and for electron and muon decay channels. We place a limit on isospin breaking in $\overline{B} \to X_{u} \ell \overline{\nu}$ decays, and find no indication of lepton flavor universality violation in either the charmed or charmless mode. Furthermore, we unfold the $\overline{B} \to X_{u} \ell \overline{\nu}$ and $\overline{B} \to X_{c} \ell \overline{\nu}$ yields and report the differential ratio in lepton energy and four-momentum transfer squared.
Comment: 22 pages, 13 figures
Comment: 22 pages, 13 figures