Anomalies in B-decays and U(2) flavor symmetry

Barbieri, Riccardo; Isidori, Gino; Pattori, Andrea; Senia, Fabrizio

doi:10.1140/epjc/s10052-016-3905-3

Cited by 344 publications

(307 citation statements)

References 23 publications

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“…Models featuring vector LQs models in order to explain the flavour anomalies appeared recently in the literature [72][73][74][75], typically as new composite states. The presence of these states signals that the theory in isolation is non-renormalizable, meaning that loop effects of the vectors are UV divergent, for a recent re-discussion see ref.…”

Section: Jhep09(2017)010mentioning

confidence: 99%

Flavour anomalies after the R K ∗ measurement

D’Amico

Nardecchia

Panci

et al. 2017

J. High Energ. Phys.

256

201

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The LHCb measurement of the µ/e ratio R K * indicates a deficit with respect to the Standard Model prediction, supporting earlier hints of lepton universality violation observed in the R K ratio. We show that the R K and R K * ratios alone constrain the chiralities of the states contributing to these anomalies, and we find deviations from the Standard Model at the 4σ level. This conclusion is further corroborated by hints from the theoretically challenging b → sµ + µ − distributions. Theoretical interpretations in terms of Z , lepto-quarks, loop mediators, and composite dynamics are discussed. We highlight their distinctive features in terms of the chirality and flavour structures relevant to the observed anomalies.

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Section: Jhep09(2017)010mentioning

confidence: 99%

Flavour anomalies after the R K ∗ measurement

D’Amico

Nardecchia

Panci

et al. 2017

J. High Energ. Phys.

256

201

View full text Add to dashboard Cite

show abstract

“…Moreover, there are four types of lepto-quark (LQ) mediators giving rise to O (1) lq and O (3) lq at the tree-level [80,[94][95][96][97][98][99][100][101]. Two have spin one, U µ and U a µ , and two have spin zero, S and S a .…”

Section: Jhep09(2017)061mentioning

confidence: 99%

“…Z or leptoquarks, rely on a U(2) flavour breaking pattern [80,81,97]. Common feature of models with U(2) flavour symmetries is the existence of small flavour symmetry breaking parameters which suppress the coupling of NP with the first two fermion generations.…”

Section: Models With U(2) Flavour Symmetriesmentioning

confidence: 99%

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On the importance of electroweak corrections for B anomalies

Feruglio

Paradisi

Pattori

2017

J. High Energ. Phys.

Self Cite

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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“…The discrepancy between experiment and the SM is at the level of 4σ, and it can be explained with new physics (NP) [11,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. These analyses of the data are most fruitful when casted model-independently in an effective field theoretical framework.…”

Section: Introductionmentioning

confidence: 99%

New physics in the kinematic distributions of B¯→D(*)τ−(→

2016

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We investigate the experimentally-accessible kinematic distributions of theB → D ( * ) τ − (→ −ν ντ )ντ decays. Specifically, we study the decay rates as functions of the B → D ( * ) transferred squared momentum, the energy of the final charged lepton and the angle of its 3-momentum with respect to the 3-momentum of the recoiling D ( * ) . The angular distribution allows to introduce new observables, like a forward-backward asymmetry, which are complementary to the total rates. We present analytic formulas for the observable 3-fold 5-body differential decay rates, study the predictions in the Standard Model and investigate the effects in different new-physics scenarios that we characterize using an effective field theory framework.

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Anomalies in B-decays and U(2) flavor symmetry

Abstract: The collection of a few anomalies in semileptonic B-decays invites to speculate about the emergence of some strikingly new phenomena. Here we offer a possible interpretation of these anomalies in the context of a weakly broken U (2) 5 flavor symmetry and leptoquark mediators.

Cited by 344 publications

References 23 publications

Flavour anomalies after the R K ∗ measurement

Flavour anomalies after the R K ∗ measurement

On the importance of electroweak corrections for B anomalies

New physics in the kinematic distributions of B¯→D(*)τ−(→

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