Precision flavour physics with B → K νν̄ and B → Kl + l −

260

166

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.

Section: Jhep02(2015)184supporting

confidence: 88%

“…In analogy to the case of LFNU, one can now define 37) and (3.30) still hold with the replacements , η → ij , η ij . Note that in the SM, ij = 0 for i = j.…”

Section: Lfvmentioning

confidence: 99%

See 1 more Smart Citation

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

Buras

Girrbach-Noe

Niehoff

et al. 2015

260

166

“…Since the form factors not only determine the leading operator contributions but also enter the factorizable nonlocal effects, we expect that the hadronic input in B → Kℓ + ℓ − is currently under a better control than in B → K * ℓ + ℓ − . This circumstance strengthens the case for using the kaon channel as a perspective tool to trace generic new physics (see e.g., [10,11]). …”

Section: Introductionsupporting

confidence: 56%

B → Kℓ + ℓ − decay at large hadronic recoil

Khodjamirian

Mannel

Wang

2013

182

198

Abstract:We predict the amplitude of the B → Kℓ + ℓ − decay in the region of the dilepton invariant mass squared 0 < q 2 ≤ m 2 J/ψ , that is, at large hadronic recoil. The B → K form factors entering the factorizable part of the decay amplitude are obtained from QCD light-cone sum rules. The nonlocal effects, generated by the four-quark and penguin operators combined with the electromagnetic interaction, are calculated at q 2 < 0, far below the hadronic thresholds. For hard-gluon contributions we employ the QCD factorization approach. The soft-gluon nonfactorizable contributions are estimated from QCD light-cone sum rules. The result of the calculation is matched to the hadronic dispersion relation in the variable q 2 , which is then continued to the kinematical region of the decay. The overall effect of nonlocal contributions in B → Kℓ + ℓ − at large hadronic recoil is moderate. The main uncertainty of the predicted B → Kℓ + ℓ − partial width is caused by the B → K form factors. Furthermore, the isospin asymmetry in this decay is expected to be very small. We investigate the deviation of the observables from the Standard Model predictions by introducing a generic new physics contribution to the effective Hamiltonian.

“…small invariant lepton mass q 2 ) [19][20][21][22][23][24][25][26][27]. Furthermore it seems a rather non-trivial task to construct realistic models for the effect of intermediate vector-meson resonances contributing to the q 2 spectrum in B → K ( * ) + − decays above and below the cc threshold, see e.g.…”

Section: Jhep08(2017)105mentioning

confidence: 99%

D → ρℓ + ℓ − decays in the QCD factorization approach

Feldmann¹,

Müller²,

Seidel³

2017

We consider rare semileptonic decays of a heavy D-meson into a light vector meson in the framework of QCD factorization. In contrast to the corresponding B-meson decays, the naive factorization hypothesis does not even serve as a first approximation. Rather, the decay amplitudes appear to be dominated by non-factorizable dynamics, e.g. through annihilation topologies, which are particularly sensitive to long-distance hadronic contributions. We therefore pay particular attention to intermediate vector-meson resonances appearing in quark-loop and annihilation topologies. Compared to the analogous B-meson decays, we identify a number of effects that result in very large theoretical uncertainties for differential decay rates. Some of these effects are found to cancel in the ratio of partially integrated decay rates for transversely and longitudinally polarized ρ mesons. On the phenomenological side this implies a very limited potential to constrain physics beyond the Standard Model by means of these decays.