A global likelihood for precision constraints and flavour anomalies

Aebischer, Jason; Kumar, Jacky; Stangl, Peter; Straub, David M.

doi:10.1140/epjc/s10052-019-6977-z

Cited by 146 publications

(153 citation statements)

References 187 publications

(301 reference statements)

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“…from CKM matrix elements) are based on flavio v1.3 with default settings [48]. For more details on the statistical approach and the list of observables and measurements included, we refer the reader to [47].…”

Section: Setupmentioning

confidence: 99%

“…In this paper we will explore the implications of all these, as well as other data, to be described in fuller detail in the next section, in the context of global fits to model-independent new physics scenarios, identify those that lead to a good description of the data, and discuss possible realizations in terms of simplified new-physics models. Our numerical analysis is entirely based on open-source software, notably the global likelihood in Wilson coefficient space provided by the smelli package [47], built on flavio [48] and wilson [49]. As such, our analysis is easily reproducible and modifiable.…”

Section: Introductionmentioning

confidence: 99%

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B-decay discrepancies after Moriond 2019

et al. 2020

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Following the updated measurement of the lepton flavour universality (LFU) ratio R K in B → K decays by LHCb, as well as a number of further measurements, e.g. R K * by Belle and B s → µµ by ATLAS, we analyse the global status of new physics in b → s transitions in the weak effective theory at the b-quark scale, in the Standard Model effective theory above the electroweak scale, and in simplified models of new physics. We find that the data continues to strongly prefer a solution with new physics in semi-leptonic Wilson coefficients. A purely muonic contribution to the combination C 9 = −C 10 , well suited to UV-complete interpretations, is now favoured with respect to a muonic contribution to C 9 only. An even better fit is obtained by allowing an additional LFU shift in C 9 . Such a shift can be renormalization-group induced from four-fermion operators above the electroweak scale, in particular from semi-tauonic operators, able to account for the potential discrepancies in b → c transitions. This scenario is naturally realized in the simplified U 1 leptoquark model. We also analyse simplified models where a LFU effect in b → s is induced radiatively from four-quark operators and show that such a setup is on the brink of exclusion by LHC di-jet resonance searches.

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Section: Setupmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

B-decay discrepancies after Moriond 2019

et al. 2020

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“…+0.21 −0.16 (syst.) [7,8], they provide valuable information about the spin structure of the interaction involved in B → D ( * ) τν decays, and are good observables to test various NP scenarios [37][38][39][40][41][42]. Measurements of the angular observables in these decays will be considerably improved in the future [43,44].…”

Section: Introductionmentioning

confidence: 99%

Phenomenology of decays in a scalar leptoquark model *

2019

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During the past few years, hints of Lepton Flavour Universality (LFU) violation have been observed in b → cτν and b → s + − transitions. Recently, the D * and τ polarization fractions P D * L and P τ L in B → D * τν decay have also been measured by the Belle collaboration. Motivated by these intriguing results, we revisit the R D ( * ) and R K ( * ) anomalies in a scalar leptoquark (LQ) model, in which two scalar LQs, one being SU (2) L singlet and the other SU (2) L triplet, are introduced simultaneously. We consider five b → cτν mediated decays, B → D ( * ) τν, B c → η c τν, B c → J/ψτν, and Λ b → Λ c τν, and focus on the LQ effects on the q 2 distributions of the branching fractions, the LFU ratios, and the various angular observables in these decays. Under the combined constraints by the available data on R D ( * ) , R J/ψ , P τ L (D * ), and P D * L , we perform scans for the LQ couplings and make predictions for a number of observables. It is found numerically that both the differential branching fractions and the LFU ratios are largely enhanced by the LQ effects, with the latter being expected to provide testable signatures at the SuperKEKB and High-Luminosity LHC experiments.results of R D and R D * with a semileptonic tagging method [94,95]. The measured values are R exp D = 0.307 ± 0.037 (stat.) ± 0.016 (syst.) and R exp D * = 0.283 ± 0.018 (stat.) ± 0.014 (syst.). After including this new measurement, the world averages become to R avg, 2019 D = 0.337 ± 0.030

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“…Recently, some correlations between B-physics anomalies and in particular τ decays through renormalization group effects have been pointed out in various papers but mostly in the context of leptoquark models or in the context of SMEFT analyses of these anomalies. Selected papers can be found in [20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Quark-lepton connections in Z′ mediated FCNC processes: gauge anomaly cancellations at work

Aebischer

Buras

Cerdà-Sevilla

et al. 2020

J. High Energ. Phys.

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We consider scenarios with a heavy Z gauge boson with flavour non-universal quark and lepton couplings with the goal to illustrate how the cancellation of gauge anomalies generated by the presence of an additional U(1) gauge symmetry would imply correlations between FCNC processes within the quark sector, within the lepton sector and most interestingly between quark flavour and lepton flavour violating processes. To this end we present simple scenarios with only left-handed flavour-violating Z couplings and those in which also right-handed flavour-violating couplings are present. The considered scenarios are characterized by a small number of free parameters but in contrast to gauge anomaly cancellation in the Standard Model, in which it takes place separately within each generation, in our scenarios anomaly cancellation involves simultaneously quarks and leptons of all three generations. Our models involve, beyond the ordinary quarks and leptons, three heavy right-handed neutrinos. The models with only left-handed FCNCs of Z involve beyond g Z and M Z two real parameters characterizing the charges of all fermions under the U(1) gauge symmetry and the CKM and PMNS ones in the quark and lepton sectors, respectively. The models with the right-handed FCNCs of Z involve few additional parameters. Imposing constraints from well measured ∆F = 2 observables we identify a number of interesting correlations that involve e.g. ε /ε, B s,d → µ + µ − , B → K(K * ) + − , K + → π + νν, K L → π 0 νν and purely lepton flavour violating decays like µ → eγ, µ → 3e, τ → 3µ and µ − e conversion among others. Also (g − 2) µ,e are considered. The impact of the experimental µ → eγ, µ → 3e and in particular µ − e conversion bounds on rare K and B decays is emphasized.

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A global likelihood for precision constraints and flavour anomalies

Cited by 146 publications

References 187 publications

B-decay discrepancies after Moriond 2019

B-decay discrepancies after Moriond 2019

Phenomenology of decays in a scalar leptoquark model *

Quark-lepton connections in Z′ mediated FCNC processes: gauge anomaly cancellations at work

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