BelleBELLE2-CONF-PH-2022-017 November 7 2022 Determination of jVubjfrom untagged B0decays using
2025-04-27
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Belle
BELLE2-CONF-PH-2022-017
November 7, 2022
Determination of |Vub|from untagged B0→π−`+ν`decays using
2019-2021 Belle II data
(The Belle II Collaboration)
F. Abudin´en, I. Adachi, K. Adamczyk, L. Aggarwal, P. Ahlburg, H. Ahmed, J. K. Ahn, H.
Aihara, N. Akopov, A. Aloisio, F. Ameli, L. Andricek, N. Anh Ky, D. M. Asner, H.
Atmacan, V. Aulchenko, T. Aushev, V. Aushev, T. Aziz, V. Babu, S. Bacher, H. Bae, S.
Baehr, S. Bahinipati, A. M. Bakich, P. Bambade, Sw. Banerjee, S. Bansal, M. Barrett, G.
Batignani, J. Baudot, M. Bauer, A. Baur, A. Beaubien, A. Beaulieu, J. Becker, P. K.
Behera, J. V. Bennett, E. Bernieri, F. U. Bernlochner, V. Bertacchi, M. Bertemes, E.
Bertholet, M. Bessner, S. Bettarini, V. Bhardwaj, B. Bhuyan, F. Bianchi, T. Bilka, S.
Bilokin, D. Biswas, A. Bobrov, D. Bodrov, A. Bolz, A. Bondar, G. Bonvicini, A. Bozek, M.
Braˇcko, P. Branchini, N. Braun, R. A. Briere, T. E. Browder, D. N. Brown, A. Budano, L.
Burmistrov, S. Bussino, M. Campajola, L. Cao, G. Casarosa, C. Cecchi, D. ˇ
Cervenkov,
M.-C. Chang, P. Chang, R. Cheaib, P. Cheema, V. Chekelian, C. Chen, Y. Q. Chen, Y. Q.
Chen, Y.-T. 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, L. M. Cremaldi, S. Cunliffe, T.
Czank, S. Das, N. Dash, F. Dattola, E. De La Cruz-Burelo, S. A. De La Motte, G. de
Marino, G. De Nardo, M. De Nuccio, G. De Pietro, R. de Sangro, B. Deschamps, M.
Destefanis, S. Dey, A. De Yta-Hernandez, R. Dhamija, A. Di Canto, F. Di Capua, S. Di
Carlo, J. Dingfelder, Z. Doleˇzal, I. Dom´ınguez Jim´enez, T. V. Dong, M. Dorigo, K.
Dort, D. Dossett, S. Dreyer, S. Dubey, S. Duell, G. Dujany, P. Ecker, S. Eidelman, M.
Eliachevitch, D. Epifanov, P. Feichtinger, T. Ferber, D. Ferlewicz, T. Fillinger, C. Finck,
G. Finocchiaro, P. Fischer, K. Flood, A. Fodor, F. Forti, A. Frey, M. Friedl, B. G. Fulsom,
M. Gabriel, A. Gabrielli, N. Gabyshev, E. Ganiev, M. Garcia-Hernandez, R. Garg,
A. Garmash, V. Gaur, A. Gaz, U. Gebauer, A. Gellrich, J. Gemmler, T. Geßler, G.
Ghevondyan, G. Giakoustidis, R. Giordano, A. Giri, A. Glazov, B. Gobbo, R. Godang, P.
Goldenzweig, B. Golob, P. Gomis, G. Gong, P. Grace, W. Gradl, S. Granderath, E.
Graziani, D. Greenwald, T. Gu, Y. Guan, K. Gudkova, J. Guilliams, C. Hadjivasiliou, S.
Halder, K. Hara, T. Hara, O. Hartbrich, K. Hayasaka, H. Hayashii, S. Hazra, C. Hearty,
M. T. Hedges, I. Heredia de la Cruz, M. Hern´andez Villanueva, A. Hershenhorn, T.
Higuchi, E. C. Hill, H. Hirata, M. Hoek, M. Hohmann, S. Hollitt, T. Hotta, C.-L. Hsu, K.
Huang, T. Humair, T. Iijima, K. Inami, G. Inguglia, N. Ipsita, J. Irakkathil Jabbar, A.
Ishikawa, S. Ito, R. Itoh, M. Iwasaki, Y. Iwasaki, S. Iwata, P. Jackson, W. W. Jacobs, D.
E. Jaffe, E.-J. Jang, M. Jeandron, H. B. Jeon, Q. P. Ji, S. Jia, Y. Jin, C. Joo, K. K. Joo,
H. Junkerkalefeld, I. Kadenko, J. Kahn, H. Kakuno, M. Kaleta, A. B. Kaliyar, J. Kandra,
K. H. Kang, S. Kang, P. Kapusta, R. Karl, G. Karyan, Y. Kato, H. Kawai, T. Kawasaki,
C. Ketter, H. Kichimi, C. Kiesling, C.-H. Kim, D. Y. Kim, H. J. Kim, K.-H. Kim, K. Kim,
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arXiv:2210.04224v2 [hep-ex] 7 Nov 2022
S.-H. Kim, Y.-K. Kim, Y. Kim, T. D. Kimmel, H. Kindo, K. Kinoshita, C. Kleinwort, B.
Knysh, P. Kodyˇs, T. Koga, S. Kohani, K. Kojima, I. Komarov, T. Konno, A. Korobov, S.
Korpar, N. Kovalchuk, E. Kovalenko, R. Kowalewski, T. M. G. Kraetzschmar, F. Krinner,
P. Kriˇzan, R. Kroeger, J. F. Krohn, P. Krokovny, H. Kr¨uger, W. Kuehn, T. Kuhr, J.
Kumar, M. Kumar, R. Kumar, K. Kumara, T. Kumita, T. Kunigo, M. K¨unzel, S. Kurz, A.
Kuzmin, P. Kvasniˇcka, Y.-J. Kwon, S. Lacaprara, Y.-T. Lai, C. La Licata, K. Lalwani, T.
Lam, L. Lanceri, J. S. Lange, M. Laurenza, K. Lautenbach, P. J. Laycock, R. Leboucher,
F. R. Le Diberder, I.-S. Lee, S. C. Lee, P. Leitl, D. Levit, P. M. Lewis, C. Li, L. K. Li, S.
X. Li, Y. B. Li, J. Libby, K. Lieret, J. Lin, Z. Liptak, Q. Y. Liu, Z. A. Liu, D. Liventsev,
S. Longo, A. Loos, A. Lozar, P. Lu, T. Lueck, F. Luetticke, T. Luo, C. Lyu, C. MacQueen,
M. Maggiora, R. Maiti, S. Maity, R. Manfredi, E. Manoni, A. Manthei, S. Marcello, C.
Marinas, L. Martel, A. Martini, L. Massaccesi, M. Masuda, T. Matsuda, K. Matsuoka, D.
Matvienko, J. A. McKenna, J. McNeil, F. Meggendorfer, F. Meier, M. Merola, F. Metzner,
M. Milesi, C. Miller, K. Miyabayashi, H. Miyake, H. Miyata, R. Mizuk, K. Azmi, G. B.
Mohanty, N. Molina-Gonzalez, S. Moneta, H. Moon, T. Moon, J. A. Mora Grimaldo, T.
Morii, H.-G. Moser, M. Mrvar, F. J. M¨uller, Th. Muller, G. Muroyama, C. Murphy, R.
Mussa, I. Nakamura, K. R. Nakamura, E. Nakano, M. Nakao, H. Nakayama, H. Nakazawa,
A. Narimani Charan, M. Naruki, Z. Natkaniec, A. Natochii, L. Nayak, M. Nayak, G.
Nazaryan, D. Neverov, C. Niebuhr, M. Niiyama, J. Ninkovic, N. K. Nisar, S. Nishida, K.
Nishimura, M. H. A. Nouxman, K. Ogawa, S. Ogawa, S. L. Olsen, Y. Onishchuk, H. Ono,
Y. Onuki, P. Oskin, F. Otani, E. R. Oxford, H. Ozaki, P. Pakhlov, G. Pakhlova, A.
Paladino, T. Pang, A. Panta, E. Paoloni, S. Pardi, K. Parham, H. Park, S.-H. Park,
B. Paschen, A. Passeri, A. Pathak, S. Patra, S. Paul, T. K. Pedlar, I. Peruzzi, R.
Peschke, R. Pestotnik, F. Pham, M. Piccolo, L. E. Piilonen, G. Pinna Angioni, P. L. M.
Podesta-Lerma, T. Podobnik, S. Pokharel, L. Polat, V. Popov, C. Praz, S. Prell, E.
Prencipe, M. T. Prim, M. V. Purohit, H. Purwar, N. Rad, P. Rados, S. Raiz, A. Ramirez
Morales, R. Rasheed, N. Rauls, M. Reif, S. Reiter, M. Remnev, I. Ripp-Baudot, M. Ritter,
M. Ritzert, G. Rizzo, L. B. Rizzuto, S. H. Robertson, D. Rodr´ıguez P´erez, J. M. Roney, C.
Rosenfeld, A. Rostomyan, N. Rout, M. Rozanska, G. Russo, D. Sahoo, Y. Sakai, D. A.
Sanders, S. Sandilya, A. Sangal, L. Santelj, P. Sartori, Y. Sato, V. Savinov, B. Scavino, M.
Schnepf, M. Schram, H. Schreeck, J. Schueler, C. Schwanda, A. J. Schwartz, B. Schwenker,
M. Schwickardi, Y. Seino, A. Selce, K. Senyo, I. S. Seong, J. Serrano, M. E. Sevior, C.
Sfienti, V. Shebalin, C. P. Shen, H. Shibuya, T. Shillington, T. Shimasaki, J.-G. Shiu, B.
Shwartz, A. Sibidanov, F. Simon, J. B. Singh, S. Skambraks, J. Skorupa, K. Smith, R. J.
Sobie, A. Soffer, A. Sokolov, Y. Soloviev, E. Solovieva, S. Spataro, B. Spruck, M. Stariˇc,
S. Stefkova, Z. S. Stottler, R. Stroili, J. Strube, J. Stypula, Y. Sue, R. Sugiura, M.
Sumihama, K. Sumisawa, T. Sumiyoshi, W. Sutcliffe, S. Y. Suzuki, H. Svidras, M.
Tabata, M. Takahashi, M. Takizawa, U. Tamponi, S. Tanaka, K. Tanida, H. Tanigawa,
N. Taniguchi, Y. Tao, P. Taras, F. Tenchini, R. Tiwary, D. Tonelli, E. Torassa, N.
Toutounji, K. Trabelsi, I. Tsaklidis, T. Tsuboyama, N. Tsuzuki, M. Uchida, I. Ueda, S.
Uehara, Y. Uematsu, T. Ueno, T. Uglov, K. Unger, Y. Unno, K. Uno, S. Uno, P.
Urquijo, Y. Ushiroda, Y. V. Usov, S. E. Vahsen, R. van Tonder, G. S. Varner, K. E.
Varvell, A. Vinokurova, L. Vitale, V. Vobbilisetti, V. Vorobyev, A. Vossen, B. Wach,
E. Waheed, H. M. Wakeling, K. Wan, W. Wan Abdullah, B. Wang, C. H. Wang,
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E. Wang, M.-Z. Wang, X. L. Wang, A. Warburton, M. Watanabe, S. Watanuki, J.
Webb, S. Wehle, M. Welsch, C. Wessel, J. Wiechczynski, P. Wieduwilt, H. Windel, E.
Won, L. J. Wu, X. P. Xu, B. D. Yabsley, S. Yamada, W. Yan, S. B. Yang, H. Ye,
J. Yelton, J. H. Yin, M. Yonenaga, Y. M. Yook, K. Yoshihara, T. Yoshinobu, C. Z.
Yuan, Y. Yusa, L. Zani, Y. Zhai, J. Z. Zhang, Y. Zhang, Y. Zhang, Z. Zhang, V.
Zhilich, J. Zhou, Q. D. Zhou, X. Y. Zhou, V. I. Zhukova, V. Zhulanov, and R. ˇ
Zlebˇc´ık
(The Belle II Collaboration)
Abstract
We present an analysis of the charmless semileptonic decay B0→π−`+ν`, where `=e, µ, from
198.0 million pairs of B¯
Bmesons recorded by the Belle II detector at the SuperKEKB electron-
positron collider. The decay is reconstructed without identifying the partner Bmeson. The partial
branching fractions are measured independently for B0→π−e+νeand B0→π−µ+νµas functions
of q2(momentum transfer squared), using 3896 B0→π−e+νeand 5466 B0→π−µ+νµdecays.
The total branching fraction is found to be (1.426 ±0.056 ±0.125) ×10−4for B0→π−`+ν`decays,
where the uncertainties are statistical and systematic, respectively. By fitting the measured partial
branching fractions as functions of q2, together with constraints on the nonperturbative hadronic
contribution from lattice QCD calculations, the magnitude of the Cabibbo-Kobayashi-Maskawa
matrix element Vub, (3.55 ±0.12 ±0.13 ±0.17) ×10−3, is extracted. Here, the first uncertainty is
statistical, the second is systematic and the third is theoretical.
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1. INTRODUCTION
The Cabibbo-Kobayashi-Maskawa (CKM) matrix elements are fundamental parameters
of the Standard Model (SM) of particle physics [1]. The magnitude of the matrix element
Vub can be determined by measuring the differential decay rate of B→Xu`ν events,
which is proportional to |Vub|2. Here, Xuis a charmless hadronic final state and `is a
light charged lepton. One method to measure |Vub|is inclusive, where no specific Xufinal
state is reconstructed, but rather the sum of all possible final states is analysed. This is
in contrast to the exclusive method in which a specific final state is studied. The two
methods have complementary uncertainties introduced by theoretical QCD descriptions. In
inclusive decays, these descriptions involve the calculation of the total semileptonic rate,
while in the exclusive case they take the form of parameterizations of the low-energy strong
interactions (form factors). However, the results for |Vub|obtained by the two methods
differ significantly [2]. In order to resolve this disagreement, further measurements using
novel approaches are beneficial.
The decay B0→π−`+ν`(with charge conjugation implied throughout) is experimentally
and theoretically the most reliable mode to measure |Vub|through an exclusive channel
at the BFactories. Here, we present a study of this decay using data from the Belle II
detector located at the SuperKEKB electron-positron collider at KEK, in Japan. The signal
decay is reconstructed from decays of B0mesons in e+e−→Υ(4S)→B0B0events. The
reconstruction method employed here is called untagged since the signal lepton and pion
candidates are selected without prior reconstruction (tagging) of the partner Bmeson. This
leads to a high signal efficiency, but also a low purity due to higher combinatorial background
from the partner Bmeson and increased backgrounds from e+e−collisions that produce light
quark pair (continuum) events.
The events are separated into six disjoint intervals (bins) of squared momentum transfer
from the Bmeson to the pion, q2. After selecting signal events and suppressing backgrounds,
the signal yields are extracted from an extended likelihood fit to the binned two-dimensional
distribution of the energy difference ∆E, and the beam-constrained mass Mbc, both defined
below, in bins of q2. Theoretical form-factor predictions from lattice QCD are combined
with the measured differential branching fractions to determine |Vub|[3].
2. DETECTOR, DATA SET AND SIMULATION
2.1. Belle II detector
The Belle II detector [4] is located at the SuperKEKB [5] asymmetric-energy electron-
positron collider, running at or slightly below the Υ(4S) resonance energy. The detector
is composed of subdetectors arranged around the collision point in a cylindrical geometry.
The longitudinal direction is defined by the z-axis, which points approximately along the
electron-beam direction, while the transverse plane is defined by the x- and y-axes, which
point radially out of the detector ring. A superconducting magnet producing a uniform
1.5 T magnetic field oriented along the detector axis is installed outside all but the last
subdetector. Particles produced at the interaction point first traverse the vertex detector
4
摘要：
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BELLE2-CONF-PH-2022-017November7,2022DeterminationofjVubjfromuntaggedB0!`+`decaysusing2019-2021BelleIIdata(TheBelleIICollaboration)F.Abudinen,I.Adachi,K.Adamczyk,L.Aggarwal,P.Ahlburg,H.Ahmed,J.K.Ahn,H.Aihara,N.Akopov,A.Aloisio,F.Ameli,L.Andricek,N.AnhKy,D.M.Asner,H.Atmacan,V.Aulchenko,T.Aushev,V....
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时间：2025-04-27
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