Measurement of R ( D ) and R ( D ∗ ) with a Semileptonic Tagging Method

The experimental results on the ratios of branching fractions R(D) = B((B) over bar -> D tau(-)(nu) over bar (tau))/B((B) over bar -> Dl(-)(nu) over bar (e)) and R(D*) = B((B) over bar -> D*tau(-)(nu) over bar (tau))/B((B) over bar -> D*tau(-)(nu) over bar (e)), where l denotes an electr...

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Authors: Belle Collaboration, Schnell, Gunar
Format: article
Publication Date:2020
Country:España
Institution:Universidad del País Vasco
Repository:Addi. Archivo Digital para la Docencia y la Investigación
OAI Identifier:oai:addi.ehu.eus:10810/43215
Online Access:http://hdl.handle.net/10810/43215
Access Level:Open access
Keyword:decays
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spelling Measurement of R ( D ) and R ( D ∗ ) with a Semileptonic Tagging MethodBelle CollaborationSchnell, GunardecaysThe experimental results on the ratios of branching fractions R(D) = B((B) over bar -> D tau(-)(nu) over bar (tau))/B((B) over bar -> Dl(-)(nu) over bar (e)) and R(D*) = B((B) over bar -> D*tau(-)(nu) over bar (tau))/B((B) over bar -> D*tau(-)(nu) over bar (e)), where l denotes an electron or a muon, show a long-standing discrepancy with the standard model predictions, and might hint at a violation of lepton flavor universality. We report a new simultaneous measurement of R(D) and R(D*), based on a data sample containing 772 x 10(6) B (B) over bar events recorded at the T(4S) resonance with the Belle detector at the KEKB e(+) e(-) collider. In this analysis the tag-side B meson is reconstructed in a semileptonic decay mode and the signal-side tau is reconstructed in a purely leptonic decay. The measured values are R(D) = 0.307 +/- 0.037 +/- 0.016 and R(D*) = 0.283 +/- 0.018 +/- 0.014, where the first uncertainties are statistical and the second are systematic. These results are in agreement with the standard model predictions within 0.2, 1.1, and 0.8 standard deviations for R(D), R(D*), and their combination, respectively. This work constitutes the most precise measurements of R(D) and R(D*) performed to date as well as the first result for R(D) based on a semileptonic tagging method.We thank the KEKB group for excellent operation of the accelerator; the KEK cryogenics group for efficient solenoid operations; and the KEK computer group, the NII, and PNNL/EMSL for valuable computing and SINET5 network support. We acknowledge support from MEXT, JSPS and Nagoya's Tau-Lepton Physics Research Center of Nagoya University (TLPRC); ARC (Australia); FWF (Austria); NSFC and CAS Center for Excellence in Particle Physics(CCEPP) (China); MSMT (Czechia); Carl Zeiss Foundation (CZF), DFG, Excellence Cluster Universe (EXC153), and VolkswagenStiftung (VS) (Germany); DST (India); INFN (Italy); MOE, MSIP, NRF, Radiation Science Research Institute (RSRI), Foreign Large-size Research Facility Application Supporting project (FLRFAS) project, GSDC of KISTI and KREONET/GLORIAD (Korea); MNiSW and NCN (Poland), Agreement No. 14.W03.31.0026 (Russia); ARRS (Slovenia); IKERBASQUE (Spain); SNSF (Switzerland); MOE and MOST (Taiwan); and DOE and NSF (U.S.A.). We acknowledge the support provided by the Albert Shimmins Fund for the writing of this Letter.American Physical Society202020202020info:eu-repo/semantics/articleapplication/pdfhttp://hdl.handle.net/10810/43215reponame:Addi. Archivo Digital para la Docencia y la Investigacióninstname:Universidad del País VascoIngléshttps://journals.aps.org/prl/abstract/10.1103/PhysRevLett.124.161803info:eu-repo/semantics/openAccesshttp://creativecommons.org/licenses/by/3.0/es/Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.Atribución 3.0 Españaoai:addi.ehu.eus:10810/432152026-06-18T09:23:17Z
dc.title.none.fl_str_mv Measurement of R ( D ) and R ( D ∗ ) with a Semileptonic Tagging Method
title Measurement of R ( D ) and R ( D ∗ ) with a Semileptonic Tagging Method
spellingShingle Measurement of R ( D ) and R ( D ∗ ) with a Semileptonic Tagging Method
Belle Collaboration
decays
title_short Measurement of R ( D ) and R ( D ∗ ) with a Semileptonic Tagging Method
title_full Measurement of R ( D ) and R ( D ∗ ) with a Semileptonic Tagging Method
title_fullStr Measurement of R ( D ) and R ( D ∗ ) with a Semileptonic Tagging Method
title_full_unstemmed Measurement of R ( D ) and R ( D ∗ ) with a Semileptonic Tagging Method
title_sort Measurement of R ( D ) and R ( D ∗ ) with a Semileptonic Tagging Method
dc.creator.none.fl_str_mv Belle Collaboration
Schnell, Gunar
author Belle Collaboration
author_facet Belle Collaboration
Schnell, Gunar
author_role author
author2 Schnell, Gunar
author2_role author
dc.subject.none.fl_str_mv decays
topic decays
description The experimental results on the ratios of branching fractions R(D) = B((B) over bar -> D tau(-)(nu) over bar (tau))/B((B) over bar -> Dl(-)(nu) over bar (e)) and R(D*) = B((B) over bar -> D*tau(-)(nu) over bar (tau))/B((B) over bar -> D*tau(-)(nu) over bar (e)), where l denotes an electron or a muon, show a long-standing discrepancy with the standard model predictions, and might hint at a violation of lepton flavor universality. We report a new simultaneous measurement of R(D) and R(D*), based on a data sample containing 772 x 10(6) B (B) over bar events recorded at the T(4S) resonance with the Belle detector at the KEKB e(+) e(-) collider. In this analysis the tag-side B meson is reconstructed in a semileptonic decay mode and the signal-side tau is reconstructed in a purely leptonic decay. The measured values are R(D) = 0.307 +/- 0.037 +/- 0.016 and R(D*) = 0.283 +/- 0.018 +/- 0.014, where the first uncertainties are statistical and the second are systematic. These results are in agreement with the standard model predictions within 0.2, 1.1, and 0.8 standard deviations for R(D), R(D*), and their combination, respectively. This work constitutes the most precise measurements of R(D) and R(D*) performed to date as well as the first result for R(D) based on a semileptonic tagging method.
publishDate 2020
dc.date.none.fl_str_mv 2020
2020
2020
dc.type.none.fl_str_mv info:eu-repo/semantics/article
format article
dc.identifier.none.fl_str_mv http://hdl.handle.net/10810/43215
url http://hdl.handle.net/10810/43215
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.124.161803
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/3.0/es/
Atribución 3.0 España
eu_rights_str_mv openAccess
rights_invalid_str_mv http://creativecommons.org/licenses/by/3.0/es/
Atribución 3.0 España
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv American Physical Society
publisher.none.fl_str_mv American Physical Society
dc.source.none.fl_str_mv reponame:Addi. Archivo Digital para la Docencia y la Investigación
instname:Universidad del País Vasco
instname_str Universidad del País Vasco
reponame_str Addi. Archivo Digital para la Docencia y la Investigación
collection Addi. Archivo Digital para la Docencia y la Investigación
repository.name.fl_str_mv
repository.mail.fl_str_mv
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