Violation of lepton flavor and lepton flavor universality in rare kaon decays

Crivellin, Andreas; D’Ambrosio, Giancarlo; Hoferichter, Martin; Tunstall, Lewis C.

doi:10.1103/physrevd.93.074038

Cited by 68 publications

(71 citation statements)

References 144 publications

(206 reference statements)

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“…If one allows in addition for direct couplings (not only CKM induced couplings to up-quarks) to first generation quarks, a sizable effect in K → πµµ/K → πee is possible which could be tested at NA62 or KOTO [91] and interesting correlations with b → d transitions occur. Therefore, a very detailed study of our model is important and promising in order to explore the many interesting effects which can be observed by ongoing and future experiments.…”

Section: Discussionmentioning

confidence: 99%

Simultaneous explanation of R(D (∗)) and b→sμ + μ −: the last scalar leptoquarks standing

Crivellin

Müller

Ota

2017

J. High Energ. Phys.

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322

254

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Over the past years, experiments accumulated intriguing hints for new physics (NP) in flavor observables, namely in the anomalous magnetic moment of the muon (a µ ), in R(D ( * ) ) = Br(B → D ( * ) τ ν)/Br(B → D ( * ) ν) and in b → sµ + µ − transitions, which are all at the 3 − 4 σ level. In this article we point out that one can explain the R(D ( * ) ) anomaly using two scalar leptoquarks (LQs) with the same mass and coupling to fermions related via a discrete symmetry: an SU(2) L singlet and an SU(2) L triplet, both with hypercharge Y = −2/3. In this way, potentially dangerous contributions to b → sνν are avoided and non-CKM suppressed effects in R(D ( * ) ) can be generated. This allows for smaller overall couplings to fermions weakening the direct LHC bounds. In our model, R(D ( * ) ) is directly correlated to b → sτ + τ − transitions where an enhancement by orders of magnitude compared to the standard model (SM) is predicted, such that these decay modes are in the reach of LHCb and BELLE II. Furthermore, one can also naturally explain the b → sµ + µ − anomalies (including R(K)) by a C 9 = −C 10 like contribution without spoiling µ − e universality in charged current decays. In this case sizable effects in b → sτ µ transitions are predicted which are again well within the experimental reach. One can even address the longstanding anomaly in a µ , generating a sizable decay rate for τ → µγ. However, we find that out of the three anomalies R(D ( * ) ), b → sµ + µ − and a µ only two (but any two) can be explained simultaneously. We point out that a very similar phenomenology can be achieved using a vector leptoquark SU(2) L singlet with hypercharge 2/3. In this case, no tuning between couplings is necessary, but the model is non-renormalizable.

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Section: Discussionmentioning

confidence: 99%

Simultaneous explanation of R(D (∗)) and b→sμ + μ −: the last scalar leptoquarks standing

Crivellin

Müller

Ota

2017

J. High Energ. Phys.

Self Cite

322

254

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“…[16][17][18][19][20][21][22]. In the recent literature, many studies focused on the experimental signatures implied by the solution of these anomalies in specific scenarios, including kaon observables [23,24], kinematic distributions in B decays [25][26][27][28][29][30][31][32][33][34][35], the lifetime of the B − c meson [36], Υ and ψ leptonic decays [37], tau lepton searches [38,39] and dark matter [40,41].…”

Section: Jhep09(2017)061 1 Introductionmentioning

confidence: 99%

On the importance of electroweak corrections for B anomalies

Feruglio

Paradisi

Pattori

2017

J. High Energ. Phys.

139

180

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Abstract:The growing experimental indication of Lepton Flavour Universality Violation (LFUV) both in charged-and neutral-current semileptonic B-decays, has triggered many theoretical interpretations of such non-standard phenomena. Focusing on popular scenarios where the explanation of these anomalies requires New Physics at the TeV scale, we emphasise the importance of including electroweak corrections to obtain trustable predictions for the models in question. We find that the most important quantum effects are the modifications of the leptonic couplings of the W and Z vector bosons and the generation of a purely leptonic effective Lagrangian. Although our results do not provide an inescapable no-go theorem for the explanation of the B anomalies, the tight experimental bounds on Z-pole observables and τ decays challenge an explanation of the current non-standard data. We illustrate how these effects arise, by providing a detailed discussion of the running and matching procedure which is necessary to derive the low-energy effective Lagrangian.

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“…For these processes, we point out the corresponding physics opportunities at the NA62 and KOTO experiments. In particular, assuming minimal flavor violation, we comment on the required improvements in sensitivity necessary to test the B-physics anomalies in the kaon sector [33].…”

Section: Lepton Flavor (Universality) Violation In Rare Kaon Decaysmentioning

confidence: 99%

Theory of rare $K$ decays

D’Ambrosio¹

2017

Proceedings of 9th International Workshop on the CKM Unitarity Triangle — PoS(CKM2016)

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Violation of lepton flavor and lepton flavor universality in rare kaon decays

Cited by 68 publications

References 144 publications

Simultaneous explanation of R(D (∗)) and b→sμ + μ −: the last scalar leptoquarks standing

Simultaneous explanation of R(D (∗)) and b→sμ + μ −: the last scalar leptoquarks standing

On the importance of electroweak corrections for B anomalies

Theory of rare $K$ decays

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