<p>Using data samples collected by the Belle and Belle II experiments at the Υ(4<i>S</i>) resonance with integrated luminosities of 571 fb<sup><i>−</i>1</sup> and 365 fb<sup><i>−</i>1</sup>, respectively, we measure the pseudoscalar <i>B</i>-meson mass difference to be <i>m</i>(<i>B</i><sup>0</sup>) − <i>m</i>(<i>B</i><sup>+</sup>) = (0<i>.</i>495 ± 0<i>.</i>024 ± 0<i>.</i>005) MeV/<i>c</i><sup>2</sup>. The results are based on a simultaneous fit to the variable <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\({\overline{M} }_{bc}\)</EquationSource> </InlineEquation>, which is related to the <i>B</i> momentum, for <i>B</i><sup>0</sup> and <i>B</i><sup>+</sup> candidates; and to the energy dependence of <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(\mathcal{R}=\sigma ({e}^{+}{e}^{-}\to {B}^{0}{\overline{B} }^{0}) / \sigma ({e}^{+}{e}^{-}\to {B}^{+}{B}^{-})\)</EquationSource> </InlineEquation>, which is measured using changes in the average center-of-mass energy over the data taking periods. The phase-space hypothesis <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(\mathcal{R}={({p}_{{B}^{0}} /{p}_{{B}^{+}})}^{3}\)</EquationSource> </InlineEquation>, upon which previous measurements rely, is strongly disfavored by our fit; the measured mass-difference value for the phase-space hypothesis also differs significantly from our measurement. We constrain <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(\mathcal{R}\)</EquationSource> </InlineEquation> in a broader energy range than covered by the direct measurement and extract the energy dependence of <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(\mathcal{R}\)</EquationSource> </InlineEquation> in the range from the <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(B\overline{B }\)</EquationSource> </InlineEquation> threshold up to 10.59 GeV. We interpret the results using a phenomenological model and constrain the parameters of the <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(B\overline{B }\)</EquationSource> </InlineEquation> potential in the isovector channel.</p>

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Measurements of the mass difference m(B0) − m(B+) and the energy dependence of the cross-section ratio \(\sigma ({e}^{+}{e}^{-}\to {B}^{0}{\overline{B} }^{0})/\sigma ({e}^{+}{e}^{-}\to {B}^{+}{B}^{-})\) at Belle and Belle II

  • M. Abumusabh,
  • I. Adachi,
  • L. Aggarwal,
  • H. Ahmed,
  • Y. Ahn,
  • H. Aihara,
  • N. Akopov,
  • S. Alghamdi,
  • M. Alhakami,
  • A. Aloisio,
  • N. Althubiti,
  • K. Amos,
  • N. Anh Ky,
  • C. Antonioli,
  • D. M. Asner,
  • H. Atmacan,
  • T. Aushev,
  • R. Ayad,
  • V. Babu,
  • N. K. Baghel,
  • S. Bahinipati,
  • P. Bambade,
  • Sw. Banerjee,
  • M. Barrett,
  • M. Bartl,
  • J. Baudot,
  • A. Beaubien,
  • F. Becherer,
  • J. Becker,
  • J. V. Bennett,
  • F. U. Bernlochner,
  • V. Bertacchi,
  • M. Bertemes,
  • E. Bertholet,
  • M. Bessner,
  • S. Bettarini,
  • V. Bhardwaj,
  • F. Bianchi,
  • T. Bilka,
  • D. Biswas,
  • D. Bodrov,
  • A. Bondar,
  • G. Bonvicini,
  • J. Borah,
  • A. Boschetti,
  • A. Bozek,
  • M. Bračko,
  • P. Branchini,
  • R. A. Briere,
  • T. E. Browder,
  • A. Budano,
  • S. Bussino,
  • Q. Campagna,
  • M. Campajola,
  • G. Casarosa,
  • C. Cecchi,
  • P. Chang,
  • P. Cheema,
  • L. Chen,
  • B. G. Cheon,
  • C. Cheshta,
  • H. Chetri,
  • K. Chilikin,
  • J. Chin,
  • K. Chirapatpimol,
  • H.-E. Cho,
  • K. Cho,
  • S.-J. Cho,
  • S.-K. Choi,
  • S. Choudhury,
  • S. Chutia,
  • J. A. Colorado-Caicedo,
  • I. Consigny,
  • L. Corona,
  • J. X. Cui,
  • E. De La Cruz-Burelo,
  • S. A. De La Motte,
  • G. de Marino,
  • G. De Nardo,
  • G. De Pietro,
  • R. de Sangro,
  • M. Destefanis,
  • S. Dey,
  • A. Di Canto,
  • Z. Doležal,
  • I. Domínguez Jiménez,
  • T. V. Dong,
  • X. Dong,
  • M. Dorigo,
  • G. Dujany,
  • P. Ecker,
  • J. Eppelt,
  • R. Farkas,
  • P. Feichtinger,
  • T. Ferber,
  • T. Fillinger,
  • C. Finck,
  • G. Finocchiaro,
  • F. Forti,
  • B. G. Fulsom,
  • A. Gabrielli,
  • A. Gale,
  • E. Ganiev,
  • M. Garcia-Hernandez,
  • R. Garg,
  • G. Gaudino,
  • V. Gaur,
  • V. Gautam,
  • A. Gaz,
  • A. Gellrich,
  • G. Ghevondyan,
  • D. Ghosh,
  • H. Ghumaryan,
  • G. Giakoustidis,
  • R. Giordano,
  • A. Giri,
  • P. Gironella Gironell,
  • A. Glazov,
  • B. Gobbo,
  • R. Godang,
  • O. Gogota,
  • P. Goldenzweig,
  • W. Gradl,
  • E. Graziani,
  • D. Greenwald,
  • K. Gudkova,
  • I. Haide,
  • Y. Han,
  • H. Hayashii,
  • S. Hazra,
  • C. Hearty,
  • M. T. Hedges,
  • A. Heidelbach,
  • I. Heredia de la Cruz,
  • M. Hernández Villanueva,
  • T. Higuchi,
  • M. Hoek,
  • M. Hohmann,
  • R. Hoppe,
  • P. Horak,
  • X. T. Hou,
  • C.-L. Hsu,
  • T. Humair,
  • T. Iijima,
  • N. Ipsita,
  • A. Ishikawa,
  • R. Itoh,
  • M. Iwasaki,
  • D. Jacobi,
  • W. W. Jacobs,
  • D. E. Jaffe,
  • E.-J. Jang,
  • Q. P. Ji,
  • S. Jia,
  • Y. Jin,
  • A. Johnson,
  • A. B. Kaliyar,
  • J. Kandra,
  • K. H. Kang,
  • S. Kang,
  • G. Karyan,
  • F. Keil,
  • C. Kiesling,
  • D. Y. Kim,
  • J.-Y. Kim,
  • K.-H. Kim,
  • H. Kindo,
  • K. Kinoshita,
  • P. Kodyš,
  • T. Koga,
  • S. Kohani,
  • K. Kojima,
  • A. Korobov,
  • S. Korpar,
  • R. Kowalewski,
  • P. Križan,
  • P. Krokovny,
  • T. Kuhr,
  • D. Kumar,
  • K. Kumara,
  • T. Kunigo,
  • A. Kuzmin,
  • Y.-J. Kwon,
  • S. Lacaprara,
  • T. Lam,
  • L. Lanceri,
  • J. S. Lange,
  • T. S. Lau,
  • M. Laurenza,
  • R. Leboucher,
  • F. R. Le Diberder,
  • H. Lee,
  • M. J. Lee,
  • C. Lemettais,
  • P. Leo,
  • P. M. Lewis,
  • C. Li,
  • H.-J. Li,
  • L. K. Li,
  • Q. M. Li,
  • W. Z. Li,
  • Y. Li,
  • Y. B. Li,
  • Y. P. Liao,
  • J. Libby,
  • J. Lin,
  • S. Lin,
  • V. Lisovskyi,
  • M. H. Liu,
  • Q. Y. Liu,
  • D. Liventsev,
  • S. Longo,
  • A. Lozar,
  • T. Lueck,
  • C. Lyu,
  • J. L. Ma,
  • Y. Ma,
  • M. Maggiora,
  • S. P. Maharana,
  • R. Maiti,
  • G. Mancinelli,
  • R. Manfredi,
  • E. Manoni,
  • M. Mantovano,
  • D. Marcantonio,
  • M. Marfoli,
  • C. Marinas,
  • C. Martellini,
  • A. Martens,
  • T. Martinov,
  • L. Massaccesi,
  • M. Masuda,
  • D. Matvienko,
  • S. K. Maurya,
  • M. Maushart,
  • J. A. McKenna,
  • Z. Mediankin Gruberová,
  • R. Mehta,
  • F. Meier,
  • D. Meleshko,
  • M. Merola,
  • C. Miller,
  • M. Mirra,
  • K. Miyabayashi,
  • H. Miyake,
  • R. Mizuk,
  • G. B. Mohanty,
  • S. Moneta,
  • A. L. Moreira de Carvalho,
  • H.-G. Moser,
  • M. Mrvar,
  • H. Murakami,
  • I. Nakamura,
  • M. Nakao,
  • Y. Nakazawa,
  • M. Naruki,
  • Z. Natkaniec,
  • A. Natochii,
  • M. Nayak,
  • M. Neu,
  • S. Nishida,
  • R. Nomaru,
  • S. Ogawa,
  • R. Okubo,
  • H. Ono,
  • F. Otani,
  • G. Pakhlova,
  • A. Panta,
  • S. Pardi,
  • K. Parham,
  • J. Park,
  • S.-H. Park,
  • A. Passeri,
  • S. Patra,
  • S. Paul,
  • T. K. Pedlar,
  • R. Pestotnik,
  • M. Piccolo,
  • L. E. Piilonen,
  • P. L. M. Podesta-Lerma,
  • T. Podobnik,
  • C. Praz,
  • S. Prell,
  • E. Prencipe,
  • M. T. Prim,
  • S. Privalov,
  • H. Purwar,
  • P. Rados,
  • S. Raiz,
  • K. Ravindran,
  • J. U. Rehman,
  • M. Reif,
  • S. Reiter,
  • L. Reuter,
  • D. Ricalde Herrmann,
  • I. Ripp-Baudot,
  • G. Rizzo,
  • S. H. Robertson,
  • J. M. Roney,
  • A. Rostomyan,
  • N. Rout,
  • S. Saha,
  • Y. Sakai,
  • L. Salutari,
  • D. A. Sanders,
  • S. Sandilya,
  • L. Santelj,
  • C. Santos,
  • V. Savinov,
  • B. Scavino,
  • C. Schmitt,
  • S. Schneider,
  • G. Schnell,
  • M. Schnepf,
  • K. Schoenning,
  • C. Schwanda,
  • Y. Seino,
  • K. Senyo,
  • J. Serrano,
  • M. E. Sevior,
  • C. Sfienti,
  • W. Shan,
  • G. Sharma,
  • X. D. Shi,
  • T. Shillington,
  • J.-G. Shiu,
  • D. Shtol,
  • B. Shwartz,
  • A. Sibidanov,
  • F. Simon,
  • J. Skorupa,
  • R. J. Sobie,
  • M. Sobotzik,
  • A. Soffer,
  • A. Sokolov,
  • E. Solovieva,
  • S. Spataro,
  • K. Špenko,
  • B. Spruck,
  • M. Starič,
  • P. Stavroulakis,
  • R. Stroili,
  • M. Sumihama,
  • M. Takahashi,
  • U. Tamponi,
  • S. S. Tang,
  • K. Tanida,
  • F. Tenchini,
  • F. Testa,
  • A. Thaller,
  • T. Tien Manh,
  • O. Tittel,
  • R. Tiwary,
  • E. Torassa,
  • K. Trabelsi,
  • F. F. Trantou,
  • I. Ueda,
  • K. Unger,
  • Y. Unno,
  • K. Uno,
  • S. Uno,
  • P. Urquijo,
  • Y. Ushiroda,
  • S. E. Vahsen,
  • R. van Tonder,
  • K. E. Varvell,
  • M. Veronesi,
  • V. S. Vismaya,
  • L. Vitale,
  • V. Vobbilisetti,
  • R. Volpe,
  • M. Wakai,
  • S. Wallner,
  • M.-Z. Wang,
  • A. Warburton,
  • M. Watanabe,
  • S. Watanuki,
  • C. Wessel,
  • E. Won,
  • X. P. Xu,
  • B. D. Yabsley,
  • W. Yan,
  • W. Yan,
  • J. Yelton,
  • K. Yi,
  • J. H. Yin,
  • K. Yoshihara,
  • J. Yuan,
  • L. Zani,
  • F. Zeng,
  • M. Zeyrek,
  • B. Zhang,
  • V. Zhilich,
  • J. S. Zhou,
  • Q. D. Zhou,
  • L. Zhu,
  • R. Žlebčík

摘要

Using data samples collected by the Belle and Belle II experiments at the Υ(4S) resonance with integrated luminosities of 571 fb1 and 365 fb1, respectively, we measure the pseudoscalar B-meson mass difference to be m(B0) − m(B+) = (0.495 ± 0.024 ± 0.005) MeV/c2. The results are based on a simultaneous fit to the variable \({\overline{M} }_{bc}\) , which is related to the B momentum, for B0 and B+ candidates; and to the energy dependence of \(\mathcal{R}=\sigma ({e}^{+}{e}^{-}\to {B}^{0}{\overline{B} }^{0}) / \sigma ({e}^{+}{e}^{-}\to {B}^{+}{B}^{-})\) , which is measured using changes in the average center-of-mass energy over the data taking periods. The phase-space hypothesis \(\mathcal{R}={({p}_{{B}^{0}} /{p}_{{B}^{+}})}^{3}\) , upon which previous measurements rely, is strongly disfavored by our fit; the measured mass-difference value for the phase-space hypothesis also differs significantly from our measurement. We constrain \(\mathcal{R}\) in a broader energy range than covered by the direct measurement and extract the energy dependence of \(\mathcal{R}\) in the range from the \(B\overline{B }\) threshold up to 10.59 GeV. We interpret the results using a phenomenological model and constrain the parameters of the \(B\overline{B }\) potential in the isovector channel.