Semileptonic and leptonic<i>B</i>decays, circa 2016

Ricciardi, Giulia

doi:10.1142/s0217732317300051

Cited by 19 publications

(22 citation statements)

References 245 publications

(282 reference statements)

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“…We also consider the forward-backward asymmetry 12) where θ τ is the angle between the momenta of the τ lepton and Λ c baryon in the dilepton rest frame.…”

Section: Jhep08(2017)131mentioning

confidence: 99%

“…R(D * ) and R(D) exceed the SM predictions by 3.3σ and 1.9σ, respectively. The combined analysis of R(D * ) and R(D), taking into account measurement correlations, finds that the deviation is 4σ from the SM prediction [11,12]. Since lattice QCD results are not yet available for the B → D * form factors at nonzero recoil and for the B → D tensor form factor, we use the phenomenological form factors from ref.…”

Section: Introductionmentioning

confidence: 99%

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Phenomenology of Λ b → Λ c τ ν ¯ τ $$ {\Lambda}_b\to {\Lambda}_c\tau {\overline{\nu}}_{\tau } $$ using lattice QCD calculations

Datta

Kamali

Meinel

et al. 2017

J. High Energ. Phys.

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In a recent paper we studied the effect of new-physics operators with different Lorentz structures on the semileptonic Λ b → Λ c τν τ decay. This decay is of interest in light of the R(D ( * ) ) puzzle in the semileptonicB → D ( * ) τν τ decays. In this work we add tensor operators to extend our previous results and consider both model-independent new physics (NP) and specific classes of models proposed to address the R(D ( * ) ) puzzle. We show that a measurement of R(can strongly constrain the NP parameters of models discussed for the R(D ( * ) ) puzzle. We use form factors from lattice QCD to calculate all Λ b → Λ c τν τ observables. The Λ b → Λ c tensor form factors had not previously been determined in lattice QCD, and we present new lattice results for these form factors here.

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“…We also consider the forward-backward asymmetry 12) where θ τ is the angle between the momenta of the τ lepton and Λ c baryon in the dilepton rest frame.…”

Section: Jhep08(2017)131mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Phenomenology of Λ b → Λ c τ ν ¯ τ $$ {\Lambda}_b\to {\Lambda}_c\tau {\overline{\nu}}_{\tau } $$ using lattice QCD calculations

Datta

Kamali

Meinel

et al. 2017

J. High Energ. Phys.

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“…[11] shows that the LHCb measurement lattice calculations resulted in rather small values of V ub , recent calculations give a larger value (see Ref. [18] for an overview). However, the measurement is still above the SM prediction by more than 1 σ, as can be seen from the global fit [19].…”

Section: Introductionmentioning

confidence: 98%

Importance of Loop Effects in Explaining the Accumulated Evidence for New Physics in B Decays with a Vector Leptoquark

et al. 2019

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In recent years experiments revealed intriguing hints for new physics (NP) in B decays involving b → cτ ν and b → s + − transitions at the 4 σ and 5 σ level, respectively. In addition, there are slight disagreements in b → uτ ν and b → dµ + µ − observables. While not significant on their own, they point in the same direction. Furthermore, Vus extracted from τ decays shows a slight tension (≈ 2.5 σ) with its value determined from CKM unitarity and an analysis of BELLE data found an excess in B d → τ + τ − . Concerning NP explanations, the vector leptoquark SU (2) singlet is of special interest since it is the only single particle extension of the Standard Model which can (in principle) address all the anomalies described above. For this purpose, large couplings to τ leptons are necessary and loop effects, which we calculate herein, become important. Including them in our phenomenological analysis, we find that neither the tension in Vus nor the excess in B d → τ + τ − can be fully explained without violating bounds from K → πνν. However, one can account for b → cτ ν and b → uτ ν data finding intriguing correlations with Bq → τ + τ − and K → πνν. Furthermore, the explanation of b → cτ ν predicts a positive shift in C7 and a negative one in C9, being nicely in agreement with the global fit to b → s + − data. Finally, we point out that one can fully account for b → cτ ν and b → s + − without violating bounds from τ → φµ, Υ → τ µ or b → sτ µ processes.of B → πµ + µ − [12] slightly differs from the theory expectation. Even though this is not significant on its own, the central value is very well in agreement with the expectation from b → s + − under the assumption of a V td /V ts -like scaling of the NP effect [71]. In other words, an effect of the same order and sign as in b → s + − , relative to the SM, is preferred. Furthermore, an (unpublished) analysis of BELLE data found an excess inThe ratioswhich measure LFU violation in the charged current by comparing τ modes with light leptons ( = e, µ), differ in combination from their SM predictions by ≈ 4 σ [14]. Also, the ratio R(J/ψ) = Br[B c → J/ψτ ν] Br[B c → J/ψµν][15] exceeds the SM prediction in agreement with the expectations from R(D ( * ) ) [16,17]. Concerning b → uτ ν transitions, the theory prediction for B → τ ν crucially depends on V ub . While previous arXiv:1807.02068v2 [hep-ph]

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“…A number of flavour observables appear to indicate flavour-dependent coupling of BSM physics to SM particles. A strong hint of LFU violation exists in experimental measurements [15,16] of semileptonic B-meson decays. A summary of the most recent experimental and theoretical averages for these observables may be found in table 2.…”

Section: Anomalies In Flavourmentioning

confidence: 99%

A near-minimal leptoquark model for reconciling flavour anomalies and generating radiative neutrino masses

Bigaran

Gargalionis

Volkas

2019

J. High Energ. Phys.

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We introduce two scalar leptoquarks, the SU(2) L isosinglet denoted φ ∼ (3, 1, −1/3) and the isotriplet ϕ ∼ (3, 3, −1/3), to explain observed deviations from the standard model in semi-leptonic B-meson decays. We explore the regions of parameter space in which this model accommodates the persistent tensions in the decay observables R D ( * ) , R K ( * ) , and angular observables in b → sµµ transitions. Additionally, we exploit the role of these exotics in existing models for one-loop neutrino mass generation derived from ∆L = 2 effective operators. Introducing the vector-like quark χ ∼ (3, 2, −5/6) necessary for lepton-number violation, we consider the contribution of both leptoquarks to the generation of radiative neutrino mass. We find that constraints permit simultaneously accommodating the flavour anomalies while also explaining the relative smallness of neutrino mass without the need for cancellation between leptoquark contributions. A characteristic prediction of our model is a rate of muon-electron conversion in nuclei fixed by the anomalies in b → sµµ and neutrino mass; the COMET experiment will thus test and potentially falsify our scenario. The model also predicts signatures that will be tested at the LHC and Belle II.

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Semileptonic and leptonicBdecays, circa 2016

Abstract: We summarize the status of semileptonic and leptonic B decays, including |Vcb| and |Vub| exclusive and inclusive determinations, decays to excited states of the charm meson spectrum and decays into tau leptons

Cited by 19 publications

References 245 publications

Phenomenology of Λ b → Λ c τ ν ¯ τ $$ {\Lambda}_b\to {\Lambda}_c\tau {\overline{\nu}}_{\tau } $$ using lattice QCD calculations

Phenomenology of Λ b → Λ c τ ν ¯ τ $$ {\Lambda}_b\to {\Lambda}_c\tau {\overline{\nu}}_{\tau } $$ using lattice QCD calculations

Importance of Loop Effects in Explaining the Accumulated Evidence for New Physics in B Decays with a Vector Leptoquark

A near-minimal leptoquark model for reconciling flavour anomalies and generating radiative neutrino masses

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