Abstract
In view of recent experimental indications of violations of Lepton Flavor Universality (LFU) in B decays, we analyze constraints and implications of LFU interactions, both using an effective theory approach, and an explicit dynamical model. We show that a simple dynamical model based on a SU(2) L triplet of massive vector bosons, coupled predominantly to third generation fermions (both quarks and leptons), can significantly improve the description of present data. In particular, the model decreases the tension between data and SM predictions concerning: i) the breaking of τ-μ universality in B→D(*)ℓν decays; ii) the breaking of μ-e universality in B → Kℓ+ℓ− decays. Indirectly, the model might also decrease the discrepancy between exclusive and inclusive determinations of |V cb | and |V ub |. The minimal version of the model is in tension with ATLAS and CMS direct searches for the new massive vectors (decaying into τ+τ− pairs), but this tension can be decreased with additional non-standard degrees of freedom. Further pre-dictions of the model both at low- and high-energies, in view of future high-statistics data, are discussed.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
BaBar collaboration, J.P. Lees et al., Measurement of an excess of \( \overline{B}\to {D}^{\left(\ast \right)}{\tau}^{-}{\overline{\nu}}_{\tau } \) decays and implications for charged Higgs bosons, Phys. Rev. D 88 (2013) 072012 [arXiv:1303.0571] [INSPIRE].
T. Kuhr, New B → D(*)τν result from Belle, talk presented at Flavor Physics & CP violation (FPCP2015), May 25–29, Nagoya, Japan (2015).
G. Ciezarek, New D(*)τν result from LHCb + non-B semileptonics, talk presented at Flavor Physics & CP violation (FPCP2015), May 25–29, Nagoya, Japan (2015).
LHCb collaboration, Test of lepton universality using B+ → K+ℓ+ℓ− decays, Phys. Rev. Lett. 113 (2014) 151601 [arXiv:1406.6482] [INSPIRE].
Particle Data Group collaboration K.A. Olive et al., Review of particle physics, Chin. Phys. C 38 (2014) 090001 [INSPIRE].
S. Fajfer, J.F. Kamenik and I. Nisandzic, On the \( B\to {D}^{\ast}\tau \overline{\nu}\_\tau \) sensitivity to new physics, Phys. Rev. D 85 (2012) 094025 [arXiv:1203.2654] [INSPIRE].
D. Becirevic, N. Kosnik and A. Tayduganov, \( \overline{B}\to D\tau \overline{\nu}\_\tau \) vs. \( \overline{B}\to D\mu \overline{\nu}\_\mu \), Phys. Lett. B 716 (2012) 208 [arXiv:1206.4977] [INSPIRE].
G. Hiller and F. Krüger, More model independent analysis of b → s processes, Phys. Rev. D 69 (2004) 074020 [hep-ph/0310219] [INSPIRE].
LHCb collaboration, Measurement of form-factor-independent observables in the decay B0 → K*0μ+μ−, Phys. Rev. Lett. 111 (2013) 191801 [arXiv:1308.1707] [INSPIRE].
C. Langenbruch, Latest results on rare decays from LHCb, arXiv:1505.04160.
S. Descotes-Genon, T. Hurth, J. Matias and J. Virto, Optimizing the basis of B → K*ll observables in the full kinematic range, JHEP 05 (2013) 137 [arXiv:1303.5794] [INSPIRE].
Heavy Flavor Averaging Group collaboration, Y. Amhis et al., Averages of b-hadron, c-hadron and τ-lepton properties as of summer 2014, arXiv:1412.7515 [INSPIRE].
S. Fajfer, J.F. Kamenik, I. Nisandzic and J. Zupan, Implications of lepton flavor universality violations in B decays, Phys. Rev. Lett. 109 (2012) 161801 [arXiv:1206.1872] [INSPIRE].
S. Descotes-Genon, J. Matias and J. Virto, Understanding the B → K*μ+μ− anomaly, Phys. Rev. D 88 (2013) 074002 [arXiv:1307.5683] [INSPIRE].
W. Altmannshofer and D.M. Straub, New physics in B → K*μμ?, Eur. Phys. J. C 73 (2013) 2646 [arXiv:1308.1501] [INSPIRE].
A. Datta, M. Duraisamy and D. Ghosh, Explaining the B → K*μ+μ− data with scalar interactions, Phys. Rev. D 89 (2014) 071501 [arXiv:1310.1937] [INSPIRE].
G. Hiller and M. Schmaltz, R K and future b → sℓℓ physics beyond the standard model opportunities, Phys. Rev. D 90 (2014) 054014 [arXiv:1408.1627] [INSPIRE].
G. Hiller and M. Schmaltz, Diagnosing lepton-nonuniversality in b → sℓℓ, JHEP 02 (2015) 055 [arXiv:1411.4773] [INSPIRE].
A. Crivellin and S. Pokorski, Can the differences in the determinations of V ub and V cb be explained by new physics?, Phys. Rev. Lett. 114 (2015) 011802 [arXiv:1407.1320] [INSPIRE].
S.L. Glashow, D. Guadagnoli and K. Lane, Lepton flavor violation in B decays?, Phys. Rev. Lett. 114 (2015) 091801 [arXiv:1411.0565] [INSPIRE].
B. Bhattacharya, A. Datta, D. London and S. Shivashankara, Simultaneous explanation of the R K and R(D(∗)) puzzles, Phys. Lett. B 742 (2015) 370 [arXiv:1412.7164] [INSPIRE].
B. Gripaios, M. Nardecchia and S.A. Renner, Composite leptoquarks and anomalies in B-meson decays, JHEP 05 (2015) 006 [arXiv:1412.1791] [INSPIRE].
D. Ghosh, M. Nardecchia and S.A. Renner, Hint of lepton flavour non-universality in B meson decays, JHEP 12 (2014) 131 [arXiv:1408.4097] [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 L_μ − L_τ, Phys. Rev. Lett. 114 (2015) 151801 [arXiv:1501.00993] [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].
D. Aristizabal Sierra, F. Staub and A. Vicente, Shedding light on the b → s anomalies with a dark sector, Phys. Rev. D 92 (2015) 015001 [arXiv:1503.06077] [INSPIRE].
D. Bečirević, S. Fajfer and N. Košnik, Lepton flavor nonuniversality in b → sℓ+ℓ− processes, Phys. Rev. D 92 (2015) 014016 [arXiv:1503.09024] [INSPIRE].
I. de Medeiros Varzielas and G. Hiller, Clues for flavor from rare lepton and quark decays, JHEP 06 (2015) 072 [arXiv:1503.01084] [INSPIRE].
A. Crivellin, L. Hofer, J. Matias, U. Nierste, S. Pokorski and J. Rosiek, Lepton-flavour violating B decays in generic Z′ models, arXiv:1504.07928 [INSPIRE].
A. Celis, J. Fuentes-Martin, M. Jung and H. Serodio, Family non-universal Z′ models with protected flavor-changing interactions, Phys. Rev. D 92 (2015) 1 [arXiv:1505.03079] [INSPIRE].
R. Alonso, B. Grinstein and J.M. Camalich, Lepton universality violation and lepton flavor conservation in B-meson decays, arXiv:1505.05164 [INSPIRE].
R. Barbieri, G. Isidori, J. Jones-Perez, P. Lodone and D.M. Straub, U(2) and minimal flavour violation in supersymmetry, Eur. Phys. J. C 71 (2011) 1725 [arXiv:1105.2296] [INSPIRE].
G. Blankenburg, G. Isidori and J. Jones-Perez, Neutrino masses and LFV from minimal breaking of U(3)5 and U(2)5 flavor symmetries, Eur. Phys. J. C 72 (2012) 2126 [arXiv:1204.0688] [INSPIRE].
FlaviaNet Working Group on Kaon Decays collaboration, M. Antonelli et al., An evaluation of |V u s| and precise tests of the standard model from world data on leptonic and semileptonic kaon decays, Eur. Phys. J. C 69 (2010) 399 [arXiv:1005.2323] [INSPIRE].
LHCb collaboration, Determination of the quark coupling strength |V_ub| using baryonic decays, arXiv:1504.01568 [INSPIRE].
R. Barbieri, D. Buttazzo, F. Sala and D.M. Straub, Flavour physics and flavour symmetries after the first LHC phase, JHEP 05 (2014) 105 [arXiv:1402.6677] [INSPIRE].
G. Buchalla, A.J. Buras and M.E. Lautenbacher, Weak decays beyond leading logarithms, Rev. Mod. Phys. 68 (1996) 1125 [hep-ph/9512380] [INSPIRE].
G. Isidori, Flavor physics and CP-violation, arXiv:1302.0661 [INSPIRE].
B. Stugu, Summary on tau leptonic branching ratios and universality, Nucl. Phys. Proc. Suppl. 76 (1999) 123 [hep-ex/9811048] [INSPIRE].
W. Altmannshofer, S. Gori, M. Pospelov and I. Yavin, Neutrino trident production: a powerful probe of new physics with neutrino beams, Phys. Rev. Lett. 113 (2014) 091801 [arXiv:1406.2332] [INSPIRE].
CHARM-II collaboration, D. Geiregat et al., First observation of neutrino trident production, Phys. Lett. B 245 (1990) 271 [INSPIRE].
CCFR collaboration, S.R. Mishra et al., Neutrino tridents and W Z interference, Phys. Rev. Lett. 66 (1991) 3117 [INSPIRE].
W. Altmannshofer and D.M. Straub, New physics in b → s transitions after LHC run 1, arXiv:1411.3161 [INSPIRE].
W. Altmannshofer and D.M. Straub, Implications of b → s measurements, arXiv:1503.06199.
D. Pappadopulo, A. Thamm, R. Torre and A. Wulzer, Heavy vector triplets: bridging theory and data, JHEP 09 (2014) 060 [arXiv:1402.4431] [INSPIRE].
A. Efrati, A. Falkowski and Y. Soreq, Electroweak constraints on flavorful effective theories, JHEP 07 (2015) 018 [arXiv:1503.07872] [INSPIRE].
ATLAS collaboration, Search for \( W^{\prime}\to t\overline{b} \) in the lepton plus jets final state in proton-proton collisions at a centre-of-mass energy of \( \sqrt{s}=8 \) TeV with the ATLAS detector, Phys. Lett. B 743 (2015) 235 [arXiv:1410.4103] [INSPIRE].
CMS collaboration, Search for new physics in final states with a tau and missing transverse energy using pp collisions at \( \sqrt{s}=8 \) TeV, CMS-PAS-EXO-12-011 (2012).
ATLAS collaboration, Search for new particles in events with one lepton and missing transverse momentum in pp collisions at \( \sqrt{s}=8 \) TeV with the ATLAS detector, JHEP 09 (2014)037 [arXiv:1407.7494] [INSPIRE].
ATLAS collaboration, A search for high-mass resonances decaying to τ+τ− in pp collisions at \( \sqrt{s}=8 \) TeV with the ATLAS detector, arXiv:1502.07177 [INSPIRE].
ATLAS collaboration, Search for high-mass dilepton resonances in pp collisions at \( \sqrt{s}=8 \) TeV with the ATLAS detector, Phys. Rev. D 90 (2014) 052005 [arXiv:1405.4123] [INSPIRE].
CMS collaboration, Search for resonances and quantum black holes using dijet mass spectra in proton-proton collisions at \( \sqrt{s}=8 \) TeV, Phys. Rev. D 91 (2015) 052009 [arXiv:1501.04198] [INSPIRE].
CMS collaboration, Search for anomalous \( t\overline{t} \) production in the highly-boosted all-hadronic final state, JHEP 09 (2012) 029 [Erratum ibid. 1403 (2014) 132] [arXiv:1204.2488] [INSPIRE].
CMS collaboration, Search for neutral MSSM Higgs bosons decaying to a pair of tau leptons in pp collisions, JHEP 10 (2014) 160 [arXiv:1408.3316] [INSPIRE].
N.D. Christensen and C. Duhr, FeynRules — Feynman rules made easy, Comput. Phys. Commun. 180 (2009) 1614 [arXiv:0806.4194] [INSPIRE].
C. Degrande, C. Duhr, B. Fuks, D. Grellscheid, O. Mattelaer and T. Reiter, UFO — The Universal FeynRules Output, Comput. Phys. Commun. 183 (2012) 1201 [arXiv:1108.2040] [INSPIRE].
J. Alwall et al., The automated computation of tree-level and next-to-leading order differential cross sections and their matching to parton shower simulations, JHEP 07 (2014) 079 [arXiv:1405.0301] [INSPIRE].
Open Access
This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.
Author information
Authors and Affiliations
Corresponding author
Additional information
ArXiv ePrint: 1506.01705
Rights and permissions
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0), which permits use, duplication, adaptation, distribution, and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
About this article
Cite this article
Greljo, A., Isidori, G. & Marzocca, D. On the breaking of lepton flavor universality in B decays. J. High Energ. Phys. 2015, 142 (2015). https://doi.org/10.1007/JHEP07(2015)142
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/JHEP07(2015)142