We present a measurement of the ratio of partial branching fractions of the semileptonic inclusive decays, B¯→Xuℓν¯ to B¯→Xcℓν¯, where ℓ=(e,μ), using the full Belle sample of 772×106 BB¯ pairs collected at the ϒ(4S) resonance. The identification of inclusive B¯→Xuℓν¯ decays is difficult due to the abundance of Cabibbo-Kobayashi-Maskawa-favored B¯→Xcℓν¯ events, which share a similar event topology. To minimize dependence on the modeling of these channels, a data-driven description of B¯→Xcℓν¯ is employed. 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 GeV, covering approximately 86% and 78% of the B¯→Xuℓν¯ and B¯→Xcℓν¯ phase space, respectively. We find ΔB(B¯→Xuℓν¯)/ΔB(B¯→Xcℓν¯)=(1.99±0.17stat±0.16syst)×10-2, where the uncertainties are statistical and systematic, respectively. We extract |Vub|/|Vcb| using two theoretical calculations for the partial decay rate of B¯→Xuℓν¯, finding (|Vub|/|Vcb|)BLNP=(9.81±0.42stat±0.38syst±0.51ΔΓ(B¯→Xuℓν¯)±0.20ΔΓ(B¯→Xcℓν¯))×10-2 and (|Vub|/|Vcb|)GGOU=(10.06±0.43stat±0.39syst±0.23ΔΓ(B¯→Xuℓν¯)±0.20ΔΓ(B¯→Xcℓν¯))×10-2, where the third and fourth uncertainties are from the partial decay rates of B¯→Xuℓν¯ and B¯→Xcℓν¯, 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 B¯→Xuℓν¯ decays, and find no indication of lepton flavor universality violation in either the charmed or charmless mode. Furthermore, we unfold the B¯→Xuℓν¯ and B¯→Xcℓν¯ yields and report the differential ratio in lepton energy and four-momentum transfer squared.
Measurement of the ratio of partial branching fractions of inclusive B ¯ →xuℓ ν ¯ to B ¯ →xcℓ ν ¯ and the ratio of their spectra with hadronic tagging / Hohmann, M.; Urquijo, P.; Adachi, I.; Aihara, H.; Asner, D. M.; Aushev, T.; Ayad, R.; Babu, V.; Banerjee, S.; Bauer, M.; Bennett, J.; Bernlochner, F.; Bessner, M.; Bhuyan, B.; Bilka, T.; Biswas, D.; Bobrov, A.; Bodrov, D.; Bonvicini, G.; Borah, J.; Bozek, A.; Bracko, 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.; Dolezal, 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.; Krizan, 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.; Li Gioi, L.; Liventsev, D.; Masuda, M.; Matsuda, T.; Matvienko, D.; Maurya, S. K.; Meier, F.; Merola, M.; Metzner, F.; Miyabayashi, K.; Mizuk, R.; 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.; Rohrken, 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.; Staric, 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.. - In: PHYSICAL REVIEW D. - ISSN 2470-0010. - 111:9(2025). [10.1103/PhysRevD.111.092016]
Measurement of the ratio of partial branching fractions of inclusive B ¯ →xuℓ ν ¯ to B ¯ →xcℓ ν ¯ and the ratio of their spectra with hadronic tagging
Campajola M.;De Nardo G.;Merola M.;Pardi S.;
2025
Abstract
We present a measurement of the ratio of partial branching fractions of the semileptonic inclusive decays, B¯→Xuℓν¯ to B¯→Xcℓν¯, where ℓ=(e,μ), using the full Belle sample of 772×106 BB¯ pairs collected at the ϒ(4S) resonance. The identification of inclusive B¯→Xuℓν¯ decays is difficult due to the abundance of Cabibbo-Kobayashi-Maskawa-favored B¯→Xcℓν¯ events, which share a similar event topology. To minimize dependence on the modeling of these channels, a data-driven description of B¯→Xcℓν¯ is employed. 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 GeV, covering approximately 86% and 78% of the B¯→Xuℓν¯ and B¯→Xcℓν¯ phase space, respectively. We find ΔB(B¯→Xuℓν¯)/ΔB(B¯→Xcℓν¯)=(1.99±0.17stat±0.16syst)×10-2, where the uncertainties are statistical and systematic, respectively. We extract |Vub|/|Vcb| using two theoretical calculations for the partial decay rate of B¯→Xuℓν¯, finding (|Vub|/|Vcb|)BLNP=(9.81±0.42stat±0.38syst±0.51ΔΓ(B¯→Xuℓν¯)±0.20ΔΓ(B¯→Xcℓν¯))×10-2 and (|Vub|/|Vcb|)GGOU=(10.06±0.43stat±0.39syst±0.23ΔΓ(B¯→Xuℓν¯)±0.20ΔΓ(B¯→Xcℓν¯))×10-2, where the third and fourth uncertainties are from the partial decay rates of B¯→Xuℓν¯ and B¯→Xcℓν¯, 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 B¯→Xuℓν¯ decays, and find no indication of lepton flavor universality violation in either the charmed or charmless mode. Furthermore, we unfold the B¯→Xuℓν¯ and B¯→Xcℓν¯ yields and report the differential ratio in lepton energy and four-momentum transfer squared.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
