Study of two quasidegenerate heavy sterile neutrinos in rare meson decays

Sterile neutrinos in leptonic and semileptonic decays

We address the impact of a modified Wlν coupling on a wide range of observables, such as τ leptonic and mesonic decays, leptonic decays of pseudoscalar mesons, as well as semileptonic meson decays. In particular, we concentrate on deviations from lepton flavour universality, focusing on the ratios RP = Γ(P → lν)/Γ(P → l′ν), with P = K,π,D,Ds, R(D) = Γ(B + → Dτ+ν)/Γ(B+ → Dl+ν), Rτ = Γ(τ → μνν)/Γ...

Sterile neutrinos in tau lepton decays

We study possible contributions of heavy sterile neutrinos νh to the decays τ → e(μ)ππ. From the experimental upper bounds on their rates we derive new constraints on the νh − ντ mixing in the mass region 140.5 MeV ≤ mνh ≤ 1637 MeV. We discuss cosmological and astrophysical status of νh in this mass region and compare our constraints with those recently derived by the NOMAD collaboration. PACS:...

Bounds on heavy sterile neutrinos revisited

We revise the bounds on heavy sterile neutrinos, especially in the case of their mixing with muon neutrinos in the charged current. We summarize the present experimental limits, and we reanalyze the existing data from the accelerator neutrino experiments and from Super-Kamiokande to set new bounds on a heavy sterile neutrino in the range of masses from 8 MeV to 390 MeV. We also discuss how the ...

Perturbative QCD Effects in Heavy Meson Decays

The amplitude for the exclusive nonleptonic decay of a heavy meson into two light pseudoscalar mesons is analyzed using the factorization formalism of perturbative QCD for exclusive reactions at large momentum transfer. We show that the leading contribution to such amplitudes is proportional to (rs(Q2) where Q” scales with the heavy meson mass squared. Branching ratios for a few B” decay modes ...

1/mQ CORRECTIONS IN HEAVY MESON DECAYS