Decays Of Heavy Pseudoscalar Mesons Research Articles

Sensitivity bounds on heavy neutrino mixing |UμN|2 and |UτN|2 from LHCb upgrade

Decays of heavy pseudoscalar mesons $B$, $B_c$, $B_s$ and $D_s$ at LHCb upgrade are considered, which produce either two equal sign muons or taus. In addition, we consider the analogous decays with opposite sign muons or taus. All these decays are considered to be mediated by a heavy on-shell neutrino $N$. Such decays of $B$ mesons, if not detected, will give in general stringent upper bounds on the heavy-light mixing parameter $|U_{\mu N}|^2$ as a function of the neutrino mass $M_N \sim 1$ GeV, principally due to the large expected number of produced mesons $B$. While some of the decays of the other mentioned mesons are attractive due to a weaker CKM-suppression, the expected produced number of such mesons is significantly smaller that that of $B$'s; therefore, the sensitivity bounds from such decays are in general comparable or less restrictive. When $\tau$ pairs are produced, only two types of such decays are significant: $B^{\pm}, B_{c}^{\pm} \to \tau^{\pm} \tau^{\pm} \pi^{\mp}$ (and $\tau^{\pm} \tau^{\mp} \pi^{\pm}$), giving us stringent upper bounds on $|U_{\tau N}|^2$; the other decays with a pair of $\tau$, such as $B^0 \to D^{(*)-} \tau^+ \tau^+ \pi^-$ (and $D^{(*)-} \tau^+ \tau^- \pi^+$), are prohibited or very suppressed by kinematics.

Weak decay form factors of heavy pseudoscalar mesons within a light-front constituent quark model

The transition form factors describing the semileptonic decays of heavy pseudoscalar mesons are investigated within a relativistic constituent quark model formulated on the light-front. For the first time the form factors are calculated in the whole accessible kinematical region, adopting meson wave functions derived from various effective q q interactions able to describe the meson mass spectra. It is shown that the decay rates of the B → Dℓ ν ℓ, D → Kℓ ν ℓ and D → πℓ ν ℓ weak decays are mainly governed by the effects of the confinement scale, whereas the B → πℓ ν ℓ decay rate is sensitive to the high-momentum components generated in the meson wave functions by the effective one-gluon-exchange interaction. Our results are consistent with available experimental data and predictions of lattice QCD calculations and QCD sum rules.

Semileptonic decays of D and B mesons

We report results of our ongoing investigation concerning semileptonic decays of heavy pseudoscalar mesons into pseudoscalar and vector mesons. Particular attention is paid to uncertainties in the $q^2$ and the heavy quark mass dependence of formfactors. Moreover we present a non-perturbative test to the LMK current renormalization scheme for vector current transition matrix elements and find remarkable agreement.

Semileptonic decays of heavy mesons: A status report

We present intermediate results on our ongoing investigation concerning semileptonic decays of heavy pseudoscalar mesons into pseudoscalar and vector mesons. The corresponding formfactors are evaluated at several momenta and appropriate combinations of four light and four heavy quarks, which are chosen to allow for an extrapolation into the B Meson region. In order to obtain clear groundstate signals we apply gauge invariant ``Wuppertal'' smearing to the quarks. The analysis is based on 32 quenched gauge configurations of size $24^3 \times 64$ at $\beta=6.3$, with Wilson fermions.

Does the enhancement mechanism work in non-leptonic decays of heavy pseudoscalar mesons with new flavors (b and t)?

We show that the enhancement mechanism proposed for non-leptonic decays of charmed mesons (D 0, F +) is still important for decays of pseudoscalar mesons with b flavor, while its effect is small for mesons with t flavor. For the semi-leptonic branching ratios of B − (b u ), B 0(b d ) and B S 0(b s ) we predict BR (B − → evX ∼' 9%, BR(B 0 → evX) ∼' BR(B s 0 → evX) ∼' 5%. We can also derive the enhancement of the branching ratios of uncharmed final states in B decays, i.e. BR( B − → X s u ) ∼' 20 %, BR( B 0 → X s d ) ≈ 10%, where X s u ( s d ) = K π + ... + K K K + ... .