B → K ∗ ν ν ¯ $$ B\to {K}^{\left(\ast \right)}\nu \overline{\nu} $$ decays in the Standard Model and beyond

Abstract

Abstract:We present an analysis of the rare exclusive B decays B → Kνν and B → K * νν within the Standard Model (SM), in a model-independent manner, and in a number of new physics (NP) models. Combining new form factor determinations from lattice QCD with light-cone sum rule results and including complete two-loop electroweak corrections to the SM Wilson coefficient, we obtain the SM predictions BR(B + → K + νν) = (4.0 ± 0.5) × 10 −6 and BR(B 0 → K * 0 νν) = (9.2 ± 1.0) × 10 −6 , more precise and more robust than previous estimates. Beyond the SM, we make use of an effective theory with dimension-six operators invariant under the SM gauge symmetries to relate NP effects in b → sνν transitions to b → s + − transitions and use the wealth of experimental data on B → K ( * ) + − and related modes to constrain NP effects in B → K ( * ) νν. We then consider several specific NP models, including Z models, the MSSM, models with partial compositeness, and leptoquark models, demonstrating that the correlations between b → sνν observables among themselves and with B s → µ + µ − and b → s + − transitions offer powerful tests of NP with new right-handed couplings and non-MFV interactions.

Revisiting Lepton Flavor Universality in B Decays

“…Conclusions Recent experimental data hinting at non-standard LFU breaking effects in semileptonic Bdecays [1-3, 5] stimulated many theoretical investigations of NP scenarios [7][8][9][10][11][12][13][14][15][16][17]27]. In this work, we revisited LFU in B-decays assuming a class of gauge invariant semileptonic operators at the NP scale Λ v, as in Refs.…”

“…[11][12][13][14][15][16][17]. The main new development of our study is the construction of the low-energy effective Lagrangian taking into account the running of the Wilson coefficients of a suitable operator basis and the matching conditions when mass thresholds are crossed.…”

“…Such a program has not been carried out in the literature so far and it has significant implications on the conclusions of Refs. [11][12][13][14][15][16][17]. The most important quantum effects turn out to be the modification of the leptonic couplings of the vector boson Z and the generation of a purely leptonic effective Lagrangian.…”

“…In this work, we revisited LFU in B-decays assuming a class of gauge invariant semileptonic operators at the NP scale Λ v, as in Refs. [11][12][13][14][15][16][17]. We constructed the low-energy effective Lagrangian taking into account the running effects from Λ down to v through the one-loop RGEs in the limit of exact electroweak symmetry and QED RGEs from v down to the 1 GeV scale.…”

New physics contributions to $$\bar{B}_s \rightarrow \pi ^0(\rho ^0 )\,\eta ^{(')} $$ B ¯

“…Recent studies of the phenomenology of Z have been performed in Refs. [13,[41][42][43][44][45][46][47]. For a detailed review of the physics of Z gauge bosons we refer to Ref.…”