Abstract
b → sτ+τ− measurements are highly motivated for addressing lepton-flavor-universality (LFU)-violating puzzles such as \( {R}_{K^{\left(\ast \right)}} \) anomalies. The anomalies of \( {R}_{D^{\left(\ast \right)}} \) and RJ/ψ further strengthen their necessity and importance, given that the LFU-violating hints from both involve the third-generation leptons directly. Z factories at the future e−e+ colliders stand at a great position to conduct such measurements because of their relatively high production rates and reconstruction efficiencies for B mesons at the Z pole. To fully explore this potential, we pursue a dedicated sensitivity study in four b → sτ+τ− benchmark channels, namely B0 → K*0τ+τ−, Bs → ϕτ+τ−, B+ → K+τ+τ− and Bs → τ+τ−, at the future Z factories. We develop a fully tracker-based scheme for reconstructing the signal B mesons and introduce a semi-quantitative method for estimating their major backgrounds. The simulations indicate that branching ratios of the first three channels can be measured with a precision ∼ \( \mathcal{O} \)(10−7 − 10−6) and that of Bs → τ+τ− with a precision ∼ \( \mathcal{O} \)(10−5) at Tera-Z. The impacts of luminosity and tracker resolution on the expected sensitivities are explored. The interpretations of these results in effective field theory are also presented.
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References
LHCb collaboration, Test of lepton universality with B0 → K*0ℓ+ℓ− decays, JHEP 08 (2017) 055 [arXiv:1705.05802] [INSPIRE].
Belle collaboration, Measurement of \( \mathrm{\mathcal{R}} \)(D) and \( \mathrm{\mathcal{R}} \)(D*) with a semileptonic tagging method, arXiv:1904.08794 [INSPIRE].
LHCb collaboration, Measurement of the ratio of branching fractions \( \mathrm{\mathcal{B}}\left({B}_c^{+}\to J/{\psi \tau}^{+}{\nu}_{\tau}\right)/\mathrm{\mathcal{B}}\left({B}_c^{+}\to J/\psi \mu +{\nu}_{\mu}\right) \), Phys. Rev. Lett. 120 (2018) 121801 [arXiv:1711.05623] [INSPIRE].
M. Bordone, G. Isidori and A. Pattori, On the Standard Model predictions for RK and \( {R}_{K^{\left(\ast \right)}} \), Eur. Phys. J. C 76 (2016) 440 [arXiv:1605.07633] [INSPIRE].
S. Jäger and J. Martin Camalich, Reassessing the discovery potential of the B → K*ℓ+ℓ− decays in the large-recoil region: SM challenges and BSM opportunities, Phys. Rev. D 93 (2016) 014028 [arXiv:1412.3183] [INSPIRE].
HFLAV collaboration, Averages of b-hadron, c-hadron, and τ-lepton properties as of 2018, Eur. Phys. J. C 81 (2021) 226 [arXiv:1909.12524] [INSPIRE].
A. Crivellin, D. Müller and T. Ota, Simultaneous explanation of R(D(*)) and b → sμ+μ−: the last scalar leptoquarks standing, JHEP 09 (2017) 040 [arXiv:1703.09226] [INSPIRE].
A. Crivellin, D. Müller and F. Saturnino, Flavor Phenomenology of the Leptoquark Singlet-Triplet Model, JHEP 06 (2020) 020 [arXiv:1912.04224] [INSPIRE].
LHCb collaboration, Search for the decays \( {B}_s^0 \) → τ+τ− and B0 → τ+τ−, Phys. Rev. Lett. 118 (2017) 251802 [arXiv:1703.02508] [INSPIRE].
BaBar collaboration, Search for B+ → K+τ+τ− at the BaBar experiment, Phys. Rev. Lett. 118 (2017) 031802 [arXiv:1605.09637] [INSPIRE].
LHCb collaboration, Physics case for an LHCb Upgrade II — Opportunities in flavour physics, and beyond, in the HL-LHC era, arXiv:1808.08865 [INSPIRE].
Belle-II collaboration, The Belle II Physics Book, PTEP 2019 (2019) 123C01 [Erratum ibid. 2020 (2020) 029201] [arXiv:1808.10567] [INSPIRE].
B. Capdevila, A. Crivellin, S. Descotes-Genon, L. Hofer and J. Matias, Searching for New Physics with b → sτ+τ− processes, Phys. Rev. Lett. 120 (2018) 181802 [arXiv:1712.01919] [INSPIRE].
J.F. Kamenik, S. Monteil, A. Semkiv and L.V. Silva, Lepton polarization asymmetries in rare semi-tauonic b → s exclusive decays at FCC-ee, Eur. Phys. J. C 77 (2017) 701 [arXiv:1705.11106] [INSPIRE].
CEPC Study Group collaboration, CEPC Conceptual Design Report: Volume 2 — Physics & Detector, arXiv:1811.10545 [INSPIRE].
D. d’Enterria, Physics at the FCC-ee, in 17th Lomonosov Conference on Elementary Particle Physics, (2016) [DOI] [arXiv:1602.05043] [INSPIRE].
J. Albrecht, F. Bernlochner, M. Kenzie, S. Reichert, D. Straub and A. Tully, Future prospects for exploring present day anomalies in flavour physics measurements with Belle II and LHCb, arXiv:1709.10308 [INSPIRE].
X.-C. Zheng, C.-H. Chang and Z. Pan, Production of doubly heavy-flavored hadrons at e+e− colliders, Phys. Rev. D 93 (2016) 034019 [arXiv:1510.06808] [INSPIRE].
LHCb collaboration, Measurement of the \( {B}_c^{-} \) meson production fraction and asymmetry in 7 and 13 TeV pp collisions, Phys. Rev. D 100 (2019) 112006 [arXiv:1910.13404] [INSPIRE].
LCC Physics Working Group collaboration, Tests of the Standard Model at the International Linear Collider, arXiv:1908.11299 [INSPIRE].
FCC collaboration, FCC-ee: The Lepton Collider: Future Circular Collider Conceptual Design Report Volume 2, Eur. Phys. J. ST 228 (2019) 261 [INSPIRE].
N. Berger, M. Kiehn, A. Kozlinskiy and A. Schöning, A New Three-Dimensional Track Fit with Multiple Scattering, Nucl. Instrum. Meth. A 844 (2017) 135 [arXiv:1606.04990] [INSPIRE].
T. Sjöstrand, S. Mrenna and P.Z. Skands, A Brief Introduction to PYTHIA 8.1, Comput. Phys. Commun. 178 (2008) 852 [arXiv:0710.3820] [INSPIRE].
CLEO collaboration, Hadronic structure in the decay τ− → ντπ−π0π0 and the sign of the tau-neutrino helicity, Phys. Rev. D 61 (2000) 012002 [hep-ex/9902022] [INSPIRE].
P. Ilten, Tau Decays in PYTHIA 8, Nucl. Phys. B Proc. Suppl. 253-255 (2014) 77 [arXiv:1211.6730] [INSPIRE].
A.E. Bondar et al., Novosibirsk hadronic currents for τ → 4π channels of τ decay library TAUOLA, Comput. Phys. Commun. 146 (2002) 139 [hep-ph/0201149] [INSPIRE].
DELPHES 3 collaboration, DELPHES 3, A modular framework for fast simulation of a generic collider experiment, JHEP 02 (2014) 057 [arXiv:1307.6346] [INSPIRE].
C. Chen et al., Fast simulation of the CEPC detector with Delphes, arXiv:1712.09517 [INSPIRE].
A. Mordà, Rare dileptonic B0(s) meson decays at LHCb, Ph.D. Thesis, Aix-Marseille U. (2015) [INSPIRE].
Particle Data Group collaboration, Review of Particle Physics, Phys. Rev. D 98 (2018) 030001 [INSPIRE].
C. Lippmann, Particle identification, Nucl. Instrum. Meth. A 666 (2012) 148 [arXiv:1101.3276] [INSPIRE].
H.F.W. Sadrozinski, A. Seiden and N. Cartiglia, 4D tracking with ultra-fast silicon detectors, Rept. Prog. Phys. 81 (2018) 026101 [arXiv:1704.08666] [INSPIRE].
CMS collaboration, Technical proposal for a MIP timing detector in the CMS experiment Phase 2 upgrade, CERN-LHCC-2017-027, LHCC-P-009 (2017).
BaBar and Belle collaborations, The Physics of the B Factories, Eur. Phys. J. C 74 (2014) 3026 [arXiv:1406.6311] [INSPIRE].
BaBar collaboration, Measurement of the B → \( {\overline{D}}^{\left(\ast \right)}{D}^{\left(\ast \right)}K \) branching fractions, Phys. Rev. D 83 (2011) 032004 [arXiv:1011.3929] [INSPIRE].
LHCb collaboration, First observation of the decay B0 → \( {D}^0{\overline{D}}^0{K}^{+}{\pi}^{-} \), Phys. Rev. D 102 (2020) 051102 [arXiv:2007.04280] [INSPIRE].
Belle collaboration, Evidence for B− → \( {D}_s^{+}{K}^{-}{\mathrm{\ell}}^{-}{\overline{\nu}}_{\mathrm{\ell}} \) and search for B− → \( {D}_s^{\ast +}{K}^{-}{\mathrm{\ell}}^{-}{\overline{\nu}}_{\mathrm{\ell}} \), Phys. Rev. D 86 (2012) 072007 [arXiv:1207.6244] [INSPIRE].
P. Geiger and N. Isgur, Reconciling the OZI rule with strong pair creation, Phys. Rev. D 44 (1991) 799 [INSPIRE].
FCC collaboration, FCC Physics Opportunities: Future Circular Collider Conceptual Design Report Volume 1, Eur. Phys. J. C 79 (2019) 474 [INSPIRE].
C. Bobeth and U. Haisch, New Physics in \( {\Gamma}_{12}^s:\left(\overline{s}b\right)\left(\overline{\tau}\tau \right) \) Operators, Acta Phys. Polon. B 44 (2013) 127 [arXiv:1109.1826] [INSPIRE].
P. Langacker and M. Plümacher, Flavor changing effects in theories with a heavy Z′ boson with family nonuniversal couplings, Phys. Rev. D 62 (2000) 013006 [hep-ph/0001204] [INSPIRE].
V. Barger, L. Everett, J. Jiang, P. Langacker, T. Liu and C. Wagner, Family Non-universal U(1)′ Gauge Symmetries and b → s Transitions, Phys. Rev. D 80 (2009) 055008 [arXiv:0902.4507] [INSPIRE].
V. Barger, L.L. Everett, J. Jiang, P. Langacker, T. Liu and C.E.M. Wagner, b → s Transitions in Family-dependent U(1)′ Models, JHEP 12 (2009) 048 [arXiv:0906.3745] [INSPIRE].
A. Crivellin, G. D’Ambrosio and J. Heeck, Addressing the LHC flavor anomalies with horizontal gauge symmetries, Phys. Rev. D 91 (2015) 075006 [arXiv:1503.03477] [INSPIRE].
A. Crivellin, G. D’Ambrosio and J. Heeck, Explaining h → μ±τ∓, B → K*μ+μ− and B → Kμ+μ−/B → Ke+e− in a two-Higgs-doublet model with gauged Lμ − Lτ, Phys. Rev. Lett. 114 (2015) 151801 [arXiv:1501.00993] [INSPIRE].
S.M. Boucenna, A. Celis, J. Fuentes-Martin, A. Vicente and J. Virto, Phenomenology of an SU(2) × SU(2) × U(1) model with lepton-flavour non-universality, JHEP 12 (2016) 059 [arXiv:1608.01349] [INSPIRE].
C.-W. Chiang, X.-G. He, J. Tandean and X.-B. Yuan, \( {R}_{K^{\left(\ast \right)}} \) and related b → \( s\mathrm{\ell}\overline{\mathrm{\ell}} \) anomalies in minimal flavor violation framework with Z′ boson, Phys. Rev. D 96 (2017) 115022 [arXiv:1706.02696] [INSPIRE].
J. Kumar, D. London and R. Watanabe, Combined Explanations of the b → sμ+μ− and b → \( c{\tau}^{-}\overline{\nu} \) Anomalies: a General Model Analysis, Phys. Rev. D 99 (2019) 015007 [arXiv:1806.07403] [INSPIRE].
P. Asadi, M.R. Buckley and D. Shih, It’s all right(-handed neutrinos): a new W′ model for the \( {R}_{D^{\left(\ast \right)}} \) anomaly, JHEP 09 (2018) 010 [arXiv:1804.04135] [INSPIRE].
A. Greljo, D.J. Robinson, B. Shakya and J. Zupan, R(D(*)) from W′ and right-handed neutrinos, JHEP 09 (2018) 169 [arXiv:1804.04642] [INSPIRE].
M. Abdullah, J. Calle, B. Dutta, A. Flórez and D. Restrepo, Probing a simplified, W′ model of R(D(*)) anomalies using b-tags, τ leptons and missing energy, Phys. Rev. D 98 (2018) 055016 [arXiv:1805.01869] [INSPIRE].
A. Greljo, J. Martin Camalich and J.D. Ruiz-Álvarez, Mono-τ Signatures at the LHC Constrain Explanations of B-decay Anomalies, Phys. Rev. Lett. 122 (2019) 131803 [arXiv:1811.07920] [INSPIRE].
J.D. Gómez, N. Quintero and E. Rojas, Charged current b → \( c\tau {\overline{\nu}}_{\tau } \) anomalies in a general W′ boson scenario, Phys. Rev. D 100 (2019) 093003 [arXiv:1907.08357] [INSPIRE].
R. Barbieri, C.W. Murphy and F. Senia, B-decay Anomalies in a Composite Leptoquark Model, Eur. Phys. J. C 77 (2017) 8 [arXiv:1611.04930] [INSPIRE].
R. Barbieri and A. Tesi, B-decay anomalies in Pati-Salam SU(4), Eur. Phys. J. C 78 (2018) 193 [arXiv:1712.06844] [INSPIRE].
L. Calibbi, A. Crivellin and T. Li, Model of vector leptoquarks in view of the B-physics anomalies, Phys. Rev. D 98 (2018) 115002 [arXiv:1709.00692] [INSPIRE].
M. Blanke and A. Crivellin, B Meson Anomalies in a Pati-Salam Model within the Randall-Sundrum Background, Phys. Rev. Lett. 121 (2018) 011801 [arXiv:1801.07256] [INSPIRE].
A. Crivellin, C. Greub, D. Müller and F. Saturnino, Importance of Loop Effects in Explaining the Accumulated Evidence for New Physics in B Decays with a Vector Leptoquark, Phys. Rev. Lett. 122 (2019) 011805 [arXiv:1807.02068] [INSPIRE].
S. Descotes-Genon, D. Ghosh, J. Matias and M. Ramon, Exploring New Physics in the C7-C7′ plane, JHEP 06 (2011) 099 [arXiv:1104.3342] [INSPIRE].
C. Bobeth, Updated Bq → \( \overline{\mathrm{\ell}}\mathrm{\ell} \) in the standard model at higher orders, in 49th Rencontres de Moriond on Electroweak Interactions and Unified Theories, (2014) [arXiv:1405.4907] [INSPIRE].
Y. Shen et al., Photon Reconstruction Performance at the CEPC baseline detector, arXiv:1908.09062 [INSPIRE].
L. Li, Y.-Y. Li, T. Liu and S.-J. Xu, Learning physics at future e−e+ colliders with machine, JHEP 10 (2020) 018 [arXiv:2004.15013] [INSPIRE].
T. Zheng et al., Analysis of Bc → τντ at CEPC, Chin. Phys. C 45 (2021) 023001 [arXiv:2007.08234] [INSPIRE].
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Li, L., Liu, T. b → sτ+τ− physics at future Z factories. J. High Energ. Phys. 2021, 64 (2021). https://doi.org/10.1007/JHEP06(2021)064
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DOI: https://doi.org/10.1007/JHEP06(2021)064