Abstract
Leptonic rare decays of B 0 s,d mesons offer a powerful tool to search for physics beyond the Standard Model. The B 0 s → μ + μ − decay has been observed at the Large Hadron Collider and the first measurement of the effective lifetime of this channel was presented, in accordance with the Standard Model. On the other hand, B 0 s → τ + τ − and B 0 s → e + e − have received considerably less attention: while LHCb has recently reported a first upper limit of 6.8 × 10−3 (95% C.L.) for the B 0 s → τ + τ − branching ratio, the upper bound 2.8 × 10−7 (90% C.L.) for the branching ratio of B 0 s → e + e − was reported by CDF back in 2009. We discuss the current status of the interpretation of the measurement of B 0 s → μ + μ −, and explore the space for New-Physics effects in the other B 0 s,d → ℓ + ℓ − decays in a scenario assuming flavour-universal Wilson coefficients of the relevant four-fermion operators. While the New-Physics effects are then strongly suppressed by the ratio m μ /m τ of the lepton masses in B 0 s → τ + τ −, they are hugely enhanced by m μ /m e in B 0 s → e + e − and may result in a B 0 s → e + e − branching ratio as large as about 5 times the one of B 0 s → μ + μ −, which is about a factor of 20 below the CDF bound; a similar feature arises in B 0 d → e + e −. Consequently, it would be most interesting to search for the B 0 s,d → e + e − channels at the LHC and Belle II, which may result in an unambiguous signal for physics beyond the Standard Model.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
C. Bobeth, M. Gorbahn, T. Hermann, M. Misiak, E. Stamou and M. Steinhauser, B s,d → l + l − in the Standard Model with Reduced Theoretical Uncertainty, Phys. Rev. Lett. 112 (2014) 101801 [arXiv:1311.0903] [INSPIRE].
G. Borissov, R. Fleischer and M.-H. Schune, Rare Decays and CP-violation in the B s System, Ann. Rev. Nucl. Part. Sci. 63 (2013) 205 [arXiv:1303.5575] [INSPIRE].
LHCb and CMS collaborations, Observation of the rare B 0 s → μ + μ − decay from the combined analysis of CMS and LHCb data, Nature 522 (2015) 68 [arXiv:1411.4413] [INSPIRE].
K. De Bruyn et al., Probing New Physics via the B 0 s → μ + μ − Effective Lifetime, Phys. Rev. Lett. 109 (2012) 041801 [arXiv:1204.1737] [INSPIRE].
LHCb collaboration, Measurement of the B 0 s → μ + μ − branching fraction and effective lifetime and search for B 0 → μ + μ − decays, Phys. Rev. Lett. 118 (2017) 191801 [arXiv:1703.05747] [INSPIRE].
A.J. Buras, R. Fleischer, J. Girrbach and R. Knegjens, Probing New Physics with the B s → μ + μ − Time-Dependent Rate, JHEP 07 (2013) 77 [arXiv:1303.3820] [INSPIRE].
LHCb collaboration, Search for the decays B 0 s → τ + τ − and B 0 → τ + τ −, arXiv:1703.02508 [INSPIRE].
CDF collaboration, T. Aaltonen et al., Search for the Decays B 0 s → e + μ − and B 0 s → e + e − in CDF Run II, Phys. Rev. Lett. 102 (2009) 201801 [arXiv:0901.3803] [INSPIRE].
W. Altmannshofer, C. Niehoff and D.M. Straub, B s → μ + μ − as current and future probe of new physics, JHEP 05 (2017) 076 [arXiv:1702.05498] [INSPIRE].
Y. Grossman, Z. Ligeti and E. Nardi, B → τ + τ − (X) decays: First constraints and phenomenological implications, Phys. Rev. D 55 (1997) 2768 [hep-ph/9607473] [INSPIRE].
C.-W. Chiang, X.-G. He, F. Ye and X.-B. Yuan, Constraints and Implications on Higgs FCNC Couplings from Precision Measurement of B s → μ + μ − Decay, arXiv:1703.06289 [INSPIRE].
C. Bobeth, G. Hiller and G. Piranishvili, Angular distributions of \( \overline{B}\to \overline{K}{\ell}^{+}{\ell}^{-} \) decays, JHEP 12 (2007) 040 [arXiv:0709.4174] [INSPIRE].
R. Alonso, B. Grinstein and J. Martin Camalich, SU(2) × U(1) gauge invariance and the shape of new physics in rare B decays, Phys. Rev. Lett. 113 (2014) 241802 [arXiv:1407.7044] [INSPIRE].
G. D’Ambrosio, G.F. Giudice, G. Isidori and A. Strumia, Minimal flavor violation: An Effective field theory approach, Nucl. Phys. B 645 (2002) 155 [hep-ph/0207036] [INSPIRE].
I. Dunietz, R. Fleischer and U. Nierste, In pursuit of new physics with B s decays, Phys. Rev. D 63 (2001) 114015 [hep-ph/0012219] [INSPIRE].
Y. Amhis et al., Averages of b-hadron, c-hadron and τ -lepton properties as of summer 2016, arXiv:1612.07233 [INSPIRE].
K. De Bruyn, R. Fleischer, R. Knegjens, P. Koppenburg, M. Merk and N. Tuning, Branching Ratio Measurements of B s Decays, Phys. Rev. D 86 (2012) 014027 [arXiv:1204.1735] [INSPIRE].
K. De Bruyn and R. Fleischer, A Roadmap to Control Penguin Effects in B 0 d → J/ψK 0S and B 0 s → J/ψϕ, JHEP 03 (2015) 145 [arXiv:1412.6834] [INSPIRE].
J. Charles et al., Current status of the Standard Model CKM fit and constraints on ΔF = 2 New Physics, Phys. Rev. D 91 (2015) 073007 [arXiv:1501.05013] [INSPIRE].
W. Altmannshofer, C. Niehoff, P. Stangl and D.M. Straub, Status of the B → K ∗ μ + μ − anomaly after Moriond 2017, arXiv:1703.09189 [INSPIRE].
P.J. Mohr, D.B. Newell and B.N. Taylor, CODATA Recommended Values of the Fundamental Physical Constants: 2014, Rev. Mod. Phys. 88 (2016) 035009 [arXiv:1507.07956] [INSPIRE].
Particle Data Group collaboration, C. Patrignani et al., Review of Particle Physics, Chin. Phys. C 40 (2016) 100001 [INSPIRE].
S. Aoki et al., Review of lattice results concerning low-energy particle physics, Eur. Phys. J. C 77 (2017) 112 [arXiv:1607.00299] [INSPIRE].
CMS collaboration, Measurement of the B s → μ + μ − branching fraction and search for B 0 → μ + μ − with the CMS Experiment, Phys. Rev. Lett. 111 (2013) 101804 [arXiv:1307.5025] [INSPIRE].
ATLAS collaboration, Study of the rare decays of B 0 s and B 0 into muon pairs from data collected during the LHC Run 1 with the ATLAS detector, Eur. Phys. J. C 76 (2016) 513 [arXiv:1604.04263] [INSPIRE].
A.J. Buras and R. Fleischer, Quark mixing, CP-violation and rare decays after the top quark discovery, Adv. Ser. Direct. High Energy Phys. 15 (1998) 65 [hep-ph/9704376] [INSPIRE].
L. Wolfenstein, Parametrization of the Kobayashi-Maskawa Matrix, Phys. Rev. Lett. 51 (1983) 1945 [INSPIRE].
A.J. Buras, M.E. Lautenbacher and G. Ostermaier, Waiting for the top quark mass, \( {K}^{+}\to {\pi}^{+}\nu \overline{\nu} \) , \( {B}_s^0-{\overline{B}}_s^0 \) mixing and CP asymmetries in B decays, Phys. Rev. D 50 (1994) 3433 [hep-ph/9403384] [INSPIRE].
M. Gronau and D. Wyler, On determining a weak phase from CP asymmetries in charged B decays, Phys. Lett. B 265 (1991) 172 [INSPIRE].
D. Atwood, I. Dunietz and A. Soni, Enhanced CP-violation with \( B\to K{D}^0\left({\overline{D}}^0\right) \) modes and extraction of the CKM angle gamma, Phys. Rev. Lett. 78 (1997) 3257 [hep-ph/9612433] [INSPIRE].
D. Atwood, I. Dunietz and A. Soni, Improved methods for observing CP-violation in B ± → KD and measuring the CKM phase γ, Phys. Rev. D 63 (2001) 036005 [hep-ph/0008090] [INSPIRE].
R. Fleischer and S. Ricciardi, Extraction of the weak angle γ from B to charm decays, in Proceedings of the 6th International Workshop on the CKM Unitarity Triangle (CKM 2010), Coventry U.K. (2010) [arXiv:1104.4029] [INSPIRE].
Belle-II collaboration, T. Abe et al., Belle II Technical Design Report, arXiv:1011.0352 [INSPIRE].
LHCb collaboration, Implications of LHCb measurements and future prospects, Eur. Phys. J. C 73 (2013) 2373 [arXiv:1208.3355] [INSPIRE].
A. Bevan et al., Standard Model updates and new physics analysis with the Unitarity Triangle fit, arXiv:1411.7233 [INSPIRE].
M. Blanke and A.J. Buras, Universal Unitarity Triangle 2016 and the tension between ΔM s,d and ε K in CMFV models, Eur. Phys. J. C 76 (2016) 197 [arXiv:1602.04020] [INSPIRE].
A.J. Buras, Relations between ΔM s,d and \( {B}_{s,d}\to \mu \overline{\mu} \) in models with minimal flavor violation, Phys. Lett. B 566 (2003) 115 [hep-ph/0303060] [INSPIRE].
R. Fleischer, N. Serra and N. Tuning, A New Strategy for B s Branching Ratio Measurements and the Search for New Physics in B 0 s → μ + μ −, Phys. Rev. D 82 (2010) 034038 [arXiv:1004.3982] [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: 1703.10160
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
Fleischer, R., Jaarsma, R. & Tetlalmatzi-Xolocotzi, G. In pursuit of new physics with B 0 s,d → ℓ + ℓ − . J. High Energ. Phys. 2017, 156 (2017). https://doi.org/10.1007/JHEP05(2017)156
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/JHEP05(2017)156