In pursuit of new physics with B
                            
                                
                                    s,d
                                
                                0
                             → ℓ
                            +
                            ℓ
                            −

Fleischer, Robert; Tetlalmatzi-Xolocotzi, Gilberto

doi:10.1007/jhep05(2017)156

Cited by 40 publications

(36 citation statements)

References 31 publications

(54 reference statements)

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“…We only plot the central values of the observables as the uncertainties are expected to be very small in these ratios; see for example [4,13,16] In Fig. 1, we show [10], is many orders of magnitude above the SM prediction (8.35 ± 0.39) × 10 −14 [6,7].…”

Section: Resultsmentioning

confidence: 99%

Explaining the $$R_K$$ R K and $$R_{K^*}$$ R K ∗

2017

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Recent LHCb results on R K * , the ratio of the branching fractions of B → K * μ + μ − to that of B → K * e + e − , for the dilepton invariant mass bins q 2 ≡ m 2 = [0.045-1.1] GeV 2 and [1.1-6] GeV 2 show approximately 2.5σ deviations from the corresponding Standard Model prediction in each of the bins. This, when combined with the measurement of R K (q 2 = [1 − 6] GeV 2 ), a similar ratio for the decay to a pseudo-scalar meson, highly suggests lepton non-universal new physics in semi-leptonic B meson decays. In this work, we perform a model independent analysis of these potential new physics signals and identify the operators that do the best job in satisfying all these measurements. We show that heavy new physics, giving rise to q 2 independent local 4-Fermi operators of scalar, pseudo-scalar, vector or axial-vector type, is unable to explain all the three measurements simultaneously, in particular R K * in the bin [0.045-1.1], within their experimental 1σ regions. We point out the possibility to explain R K * in the low bin by an additional light ( 20 MeV) vector boson with appropriate coupling strengths to (b s) and (ē e).

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Section: Resultsmentioning

confidence: 99%

Explaining the $$R_K$$ R K and $$R_{K^*}$$ R K ∗

2017

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“…The SM prediction for the branching ratio is B SM (B s → μ + μ − ) = 3.53 × 10 −9 [47,48] while the experimentally measured values by CMS [49] and LHCb [50] Fig. 4 The b → μ + μ − observables in the SM (blue) and for some new tensor couplings (shades of red).…”

Section: Only Sp Couplings Are Presentmentioning

confidence: 87%

Model independent new physics analysis in $$\Lambda _b\rightarrow \Lambda \mu ^+\mu ^-$$ Λ b → Λ μ + μ - decay

Das

2018

Eur. Phys. J. C

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We study the rare b → μ + μ − decay in the Standard Model and beyond. Beyond the Standard Model we include new vector and axial-vector operators, scalar and pseudo-scalar operators, and tensor operators in the effective Hamiltonian. Working in the helicity basis and using appropriate parametrization of the b → hadronic matrix elements, we give expressions of hadronic and leptonic helicity amplitudes and derive expression of double differential branching ratio with respect to dilepton invariant mass squared and cosine of lepton angle. Appropriately integrating the differential branching ratio over the lepton angle, we obtain the longitudinal polarization fraction and the leptonic forward-backward asymmetry and sequentially study the observables in the presence of the new couplings. To analyze the implications of the new vector and axial-vector couplings, we follow the current global fits to b → sμ + μ − data. While the impacts of scalar couplings can be significant, exclusiveB → X s μ + μ − data imply stringent constraints on the tensor couplings and hence the effects on b → μ + μ − are negligible.

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“…(8) and address the question of how large the branching ratio of B − → e −ν e could be due to a lift of the helicity suppression through NP effects. We have addressed a similar question for the leptonic rare decays B 0 s,d → e + e − , which could be enhanced to the level of the B 0 s,d → µ + µ − channels through new (pseudo)-scalar interactions [16]. We shall also make predictions for various semileptonic decay ratios which will allow us to fully reveal the underlying decay dynamics, and extract |V ub | while also allowing for NP contributions.…”

Section: Introductionmentioning

confidence: 99%

Decoding (pseudo)-scalar operators in leptonic and semileptonic B decays

Banelli

Fleischer

Tetlalmatzi-Xolocotzi

2018

Eur. Phys. J. C

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We consider leptonic and semileptonic , decays and present a strategy to determine short-distance coefficients of New-Physics operators and the CKM element . As the leptonic channels play a central role, we illustrate this method for (pseudo)-scalar operators which may lift the helicity suppression of the corresponding transition amplitudes arising in the Standard Model. Utilising a new result by the Belle collaboration for the branching ratio of , we explore theoretically clean constraints and correlations between New Physics coefficients for leptonic final states with and leptons. In order to obtain stronger bounds and to extract , we employ semileptonic and decays as an additional ingredient, involving hadronic form factors which are determined through QCD sum rule and lattice calculations. In addition to a detailed analysis of the constraints on the New Physics contributions following from current data, we make predictions for yet unmeasured decay observables, compare them with experimental constraints and discuss the impact of CP-violating phases of the New-Physics coefficients.

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In pursuit of new physics with B s,d 0 → ℓ + ℓ −

Cited by 40 publications

References 31 publications

Explaining the $$R_K$$ R K and $$R_{K^*}$$ R K ∗

Explaining the $$R_K$$ R K and $$R_{K^*}$$ R K ∗

Model independent new physics analysis in $$\Lambda _b\rightarrow \Lambda \mu ^+\mu ^-$$ Λ b → Λ μ + μ - decay

Decoding (pseudo)-scalar operators in leptonic and semileptonic B decays

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