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

K + → π + ν¯ν Beyond Leading Logs and Vtd ∗

The calculation of QCD corrections beyond the leading logarithmic approximation for the short-distance dominated rare decay K → πνν̄ is summarized. This analysis requires the complete O(αs) corrections to the top contribution to all orders in the top-quark mass and a two-loop renormalization group (RG) calculation for the charm contribution. The inclusion of these QCD corrections reduces conside...

K→πν¯ν decays and CKM fits

After a brief introduction to the so-called flavour problem, we discuss the role of K → πν¯ ν decays in shedding new light on this issue. In particular, we review the theoretical uncertainties in predicting Γ(K → πν¯ ν) within the SM, the sensitivity of these observables to New Physics scenarios, and the status of their experimental determination.

of B + → τ + ν decays with hadronic B tags

Threshold Resummation in B → X c l ν l Decays

We compute the QCD form factor resumming threshold logarithms in B → Xc+ l+νl decays to next-to-leading logarithmic approximation. We present an interpolation formula including soft as well as collinear effects softened by the non-vanishing charm mass which, in the N -space, reads: σN = exp ∫ 1 0 dy [

Fourth generation effects on the rare B → K ∗ ν¯ν decay

If the fourth generation fermions exist, the new quarks could influence the branching ratio of the rare B → K * ν ¯ ν decay. Two possible solutions of the fourth generation CKM factor (V * ´ ts V ´ tb) (±) are obtained as a function of the new´t-quark mass (m ´ t) from the experimental results of the B → X s γ together with the semileptonic decay B → X c ℓ¯ ν. The branching ratio of the decay B...