Flavor anomalies on the eve of the Run-2 verdict

Guadagnoli, Diego

doi:10.1142/s0217732317300063

Cited by 13 publications

(16 citation statements)

References 104 publications

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“…Necessary for theB s → γl þ l − decays of interest are the following terms in (2.1) 2 (theB d → γl þ l − case is obtained with the obvious replacement s → d) [26]: The C 7γ part in Eq. (2.2) emerges from the diagrams in Fig.…”

Section: The B → D; S Effective Hamiltonianmentioning

confidence: 99%

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Rare FCNC radiative leptonic Bs,d→γl+l−

2018

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We revisit rare radiative leptonic decays B s;d → γe þ e − and B s;d → γμ þ μ − in the standard model and provide the updated estimates for various differential distributions (the branching ratios, the forward-backward asymmetry, and R μ=e , the ratio of the differential distribution for muons over electrons in the final state). The new ingredients of this work compared to the existing theoretical analyses are the following: (i) we calculate all B d → γ and B s → γ form factors induced by the vector, axial-vector, tensor and pseudotensor quark currents within the relativistic dispersion approach based on the constituent quark picture; (ii) we perform a detailed analysis of the charm-loop contributions to radiative leptonic decays: we obtain constraints imposed by electromagnetic gauge invariance and discuss the existing ambiguities in the charmonia contributions.

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Section: The B → D; S Effective Hamiltonianmentioning

confidence: 99%

“…Several tensions with the SM at the level of 2-4σ have been reported, mainly in FCNC B-decays (a comprehensive discussion can be found in a recent review [2] and [3][4][5]). 1 The ratio in the range q 2 ∈ ½1; 6 GeV 2 (q is the momentum of the lepton pair) is 25% lower than the SM prediction at 2.6σ [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Rare FCNC radiative leptonic Bs,d→γl+l−

2018

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“…For this very reason, the radiative decay is promising even for lepton-flavor-violating searches [33,34]. As a matter of fact, the additional photon extends the sensitivity to include all the operators relevant for the previously mentioned discrepancies since the effective Hamiltonians of B 0 s → + − γ and b → s are identical.…”

Section: Jhep11(2017)184mentioning

confidence: 99%

B0 s → ℓ+ℓ−γ as a test of lepton flavor universality

Guadagnoli

Reboud

Zwicky

2017

J. High Energ. Phys.

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We discuss a number of strategies to reduce the ℬ(B s 0 → ℓ + ℓ − γ) theoretical error, and make such a measurement a new probe of the interactions that are interesting in the light of present-day flavor discrepancies. In particular, for low di-lepton invariant mass we propose to exploit the close parenthood between ℬ(B s 0 → ℓ + ℓ − γ) and the measured ℬ(B s 0 → ϕ(→K+K−)γ). For high q 2, conversely, we exploit the fact that the decay is dominated by two form-factor combinations, plus contributions from broad charmonium that we model accordingly. We construct the ratio R γ , akin to R K and likewise sensitive to lepton-universality violation. Provided the two rates in this ratio are integrated in a suitable region that minimises bremsstrahlung contributions while maximising statistics, the ratio is very close to unity and the form-factor dependence cancels to an extent that makes it a new valuable probe of lepton-universality violating contributions in the effective Hamiltonian. We finally speculate on additional ideas to extract short-distance information from resonance regions, which are theoretically interesting but statistically limited at present.

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“…The study of LFV decays is particularly interesting in light of hints of lepton nonuniversality (LNU) effects in semileptonic decays [1] and b → s transitions [2,3], which could be associated with LFV processes [4]. Possible explanations of these hints can be found in various scenarios beyond the SM, e.g.…”

Section: Introductionmentioning

confidence: 99%

Search for the lepton-flavour violating decays B0( s) → e±μ∓

Aaij¹,

Adeva²,

Adinolfi³

et al. 2018

J. High Energ. Phys.

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A search for the lepton-flavour violating decays B 0s → e ± µ ∓ and B 0 → e ± µ ∓ is performed based on a sample of proton-proton collision data corresponding to an integrated luminosity of 3 fb −1 , collected with the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The observed yields are consistent with the background-only hypothesis. Upper limits on the branching fraction of the B 0 s → e ± µ ∓ decays are evaluated both in the hypotheses of an amplitude completely dominated by the heavy eigenstate and by the light eigenstate. The results are B(B 0 s → e ± µ ∓ ) < 6.3 (5.4) × 10 −9 and B(B 0 s → e ± µ ∓ ) < 7.2 (6.0) × 10 −9 at 95% (90%) confidence level, respectively. The upper limit on the branching fraction of the B 0 → e ± µ ∓ decay is also evaluated, obtaining B(B 0 → e ± µ ∓ ) < 1.3 (1.0) × 10 −9 at 95% (90%) confidence level. These are the strongest limits on these decays to date.

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Flavor anomalies on the eve of the Run-2 verdict

Cited by 13 publications

References 104 publications

Rare FCNC radiative leptonic Bs,d→γl+l−

Rare FCNC radiative leptonic Bs,d→γl+l−

B0 s → ℓ+ℓ−γ as a test of lepton flavor universality

Search for the lepton-flavour violating decays B0( s) → e±μ∓

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