Test of lepton universality with $$ {\Lambda}_b^0\to {pK}^{-}{\mathrm{\ell}}^{+}{\mathrm{\ell}}^{-} $$ decays
R. AaijNikhef National Institute for Subatomic Physics, Amsterdam, NetherlandsCarlos Abellán BetetaPhysik-Institut, Universität Zürich, Zürich, SwitzerlandT. AckernleyOliver Lodge Laboratory, University of Liverpool, Liverpool, United KingdomB. AdevaInstituto Galego de Física de Altas Enerxías (IGFAE), Universidade de Santiago de Compostela, Santiago de Compostela, SpainM. AdinolfiH.H. Wills Physics Laboratory, University of Bristol, Bristol, United KingdomH. AfsharniaUniversité Clermont Auvergne, CNRS/IN2P3, LPC, Clermont-Ferrand, FranceC. A. AidalaUniversity of Michigan, Ann Arbor, United StatesS. AiolaINFN Sezione di Milano, Milano, ItalyZ. AjaltouniUniversité Clermont Auvergne, CNRS/IN2P3, LPC, Clermont-Ferrand, FranceS. AkarLos Alamos National Laboratory (LANL), Los Alamos, United StatesP. AlbicoccoINFN Laboratori Nazionali di Frascati, Frascati, ItalyJ. AlbrechtFakultät Physik, Technische Universität Dortmund, Dortmund, GermanyF. AlessioEuropean Organization for Nuclear Research (CERN), Geneva, SwitzerlandM. AlexanderSchool of Physics and Astronomy, University of Glasgow, Glasgow, United KingdomA. Alfonso AlberoICCUB, Universitat de Barcelona, Barcelona, SpainG. AlkhazovPetersburg Nuclear Physics Institute NRC Kurchatov Institute (PNPI NRC KI), Gatchina, RussiaP. Álvarez CartelleImperial College London, London, United KingdomA. A. AlvesInstituto Galego de Física de Altas Enerxías (IGFAE), Universidade de Santiago de Compostela, Santiago de Compostela, SpainS. AmatoUniversidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, BrazilY. AmhisUniversité Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, FranceL. AnCenter for High Energy Physics, Tsinghua University, Beijing, ChinaL. AnderliniINFN Sezione di Firenze, Firenze, ItalyG. AndreassiInstitute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, SwitzerlandM. AndreottiINFN Sezione di Ferrara, Ferrara, ItalyF. ArchilliPhysikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, GermanyJ. Arnau RomeuAix Marseille Univ, CNRS/IN2P3, CPPM, Marseille, FranceA. ArtamonovInstitute for High Energy Physics NRC Kurchatov Institute (IHEP NRC KI), Protvino, RussiaM. ArtusoSyracuse University, Syracuse, NY, United StatesK. ArzymatovYandex School of Data Analysis, Moscow, RussiaE. AslanidesAix Marseille Univ, CNRS/IN2P3, CPPM, Marseille, FranceM. AtzeniPhysik-Institut, Universität Zürich, Zürich, SwitzerlandB. AudurierINFN Sezione di Cagliari, Monserrato, ItalyS. BachmannPhysikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, GermanyJ. J. BackDepartment of Physics, University of Warwick, Coventry, United KingdomS. BakerImperial College London, London, United KingdomV. BalaguraUniversité Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, FranceW. BaldiniINFN Sezione di Ferrara, Ferrara, ItalyA. BaranovYandex School of Data Analysis, Moscow, RussiaR. J. BarlowDepartment of Physics and Astronomy, University of Manchester, Manchester, United KingdomS. BarsukUniversité Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, FranceW. BarterImperial College London, London, United KingdomM. BartoliniUniversità di Genova, Genova, ItalyF. BaryshnikovNational University of Science and Technology "MISIS", Moscow, RussiaG. BassiINFN Sezione di Pisa, Pisa, ItalyV. BatozskayaNational Center for Nuclear Research (NCBJ), Warsaw, PolandB. BatsukhSyracuse University, Syracuse, NY, United StatesA. BattigFakultät Physik, Technische Universität Dortmund, Dortmund, GermanyA. BayInstitute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, SwitzerlandM. BeckerFakultät Physik, Technische Universität Dortmund, Dortmund, GermanyF. BedeschiINFN Sezione di Pisa, Pisa, ItalyI. BediagaCentro Brasileiro de Pesquisas Físicas (CBPF), Rio de Janeiro, BrazilA. BeiterSyracuse University, Syracuse, NY, United StatesL. J. BelNikhef National Institute for Subatomic Physics, Amsterdam, NetherlandsV. BelavinYandex School of Data Analysis, Moscow, RussiaS. BelinINFN Sezione di Cagliari, Monserrato, ItalyN. BeliyUniversity of Chinese Academy of Sciences, Beijing, ChinaV. BelléeInstitute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, SwitzerlandK. BelousInstitute for High Energy Physics NRC Kurchatov Institute (IHEP NRC KI), Protvino, RussiaI. BelyaevInstitute of Theoretical and Experimental Physics NRC Kurchatov Institute (ITEP NRC KI), Moscow, RussiaG. BencivenniINFN Laboratori Nazionali di Frascati, Frascati, ItalyE. Ben-HaimLPNHE, Sorbonne Université, Paris Diderot Sorbonne Paris Cité, CNRS/IN2P3, Paris, FranceS. BensonNikhef National Institute for Subatomic Physics, Amsterdam, NetherlandsS. BeranekI. Physikalisches Institut, RWTH Aachen University, Aachen, GermanyA. BerezhnoyInstitute of Nuclear Physics, Moscow State University (SINP MSU), Moscow, RussiaR. BernetPhysik-Institut, Universität Zürich, Zürich, SwitzerlandD. BerninghoffPhysikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, GermanyH. C. BernsteinSyracuse University, Syracuse, NY, United StatesC. BertellaEuropean Organization for Nuclear Research (CERN), Geneva, SwitzerlandE. BertholetLPNHE, Sorbonne Université, Paris Diderot Sorbonne Paris Cité, CNRS/IN2P3, Paris, FranceA. BertolinINFN Sezione di Padova, Padova, ItalyC. BetancourtPhysik-Institut, Universität Zürich, Zürich, SwitzerlandF. BettiINFN Sezione di Bologna, Bologna, ItalyM. O. BettlerCavendish Laboratory, University of Cambridge, Cambridge, United KingdomIa. BezshyikoPhysik-Institut, Universität Zürich, Zürich, SwitzerlandS. BhasinH.H. Wills Physics Laboratory, University of Bristol, Bristol, United KingdomJ. BhomHenryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences, Kraków, PolandM. S. BiekerFakultät Physik, Technische Universität Dortmund, Dortmund, GermanyS. BifaniUniversity of Birmingham, Birmingham, United KingdomP. BilloirLPNHE, Sorbonne Université, Paris Diderot Sorbonne Paris Cité, CNRS/IN2P3, Paris, FranceA. BizzetiINFN Sezione di Firenze, Firenze, ItalyM. BjørnDepartment of Physics, University of Oxford, Oxford, United KingdomM. P. BlagoEuropean Organization for Nuclear Research (CERN), Geneva, SwitzerlandT. BlakeDepartment of Physics, University of Warwick, Coventry, United KingdomF. BlancInstitute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, SwitzerlandS. BluskSyracuse University, Syracuse, NY, United StatesD. BobulskaSchool of Physics and Astronomy, University of Glasgow, Glasgow, United KingdomV. BocciINFN Sezione di Roma La Sapienza, Roma, ItalyO. Boente GarcíaInstituto Galego de Física de Altas Enerxías (IGFAE), Universidade de Santiago de Compostela, Santiago de Compostela, SpainThomas BoettcherMassachusetts Institute of Technology, Cambridge, MA, United StatesA. BoldyrevNational Research University Higher School of Economics, Moscow, RussiaA. BondarPetersburg Nuclear Physics Institute NRC Kurchatov Institute (PNPI NRC KI), Gatchina, RussiaN. BondarPetersburg Nuclear Physics Institute NRC Kurchatov Institute (PNPI NRC KI), Gatchina, RussiaS. BorghiDepartment of Physics and Astronomy, University of Manchester, Manchester, United KingdomM. BorisyakYandex School of Data Analysis, Moscow, RussiaM. BorsatoPhysikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, GermanyJ. T. BorsukHenryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences, Kraków, PolandT. J. V. BowcockOliver Lodge Laboratory, University of Liverpool, Liverpool, United KingdomC. BozziINFN Sezione di Ferrara, Ferrara, ItalyM. J. BradleyImperial College London, London, United KingdomS. BraunPhysikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
2020en
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Annotatsiya
A bstract The ratio of branching fractions of the decays $$ {\Lambda}_b^0 $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>Λ</mml:mi> <mml:mi>b</mml:mi> <mml:mn>0</mml:mn> </mml:msubsup> </mml:math> → pK − e + e − and $$ {\Lambda}_b^0 $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>Λ</mml:mi> <mml:mi>b</mml:mi> <mml:mn>0</mml:mn> </mml:msubsup> </mml:math> → pK − μ + μ − , $$ {R}_{pK}^{-1} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>R</mml:mi> <mml:mi>pK</mml:mi> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> , is measured for the first time using proton-proton collision data corresponding to an integrated luminosity of 4 . 7 fb − 1 recorded with the LHCb experiment at center-of-mass energies of 7, 8 and 13 TeV. In the dilepton mass-squared range 0 . 1 < q 2 < 6 . 0 GeV 2 /c 4 and the pK − mass range m ( pK − ) < 2600 MeV /c 2 , the ratio of branching fractions is measured to be $$ {R}_{pK}^{-1}={1.17}_{-0.16}^{+0.18}\pm 0.07 $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>R</mml:mi> <mml:mi>pK</mml:mi> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mn>1.17</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.16</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.18</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo>±</mml:mo> <mml:mn>0.07</mml:mn> </mml:math> , where the first uncertainty is statistical and the second systematic. This is the first test of lepton universality with b baryons and the first observation of the decay $$ {\Lambda}_b^0 $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>Λ</mml:mi> <mml:mi>b</mml:mi> <mml:mn>0</mml:mn> </mml:msubsup> </mml:math> → pK − e + e − .
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