Pietro Santorelli

Exclusive semileptonic and nonleptonic decays of the B c meson

We study exclusive nonleptonic and semileptonic decays of the B{sub c}-meson within a relativistic constituent quark model previously developed by us. For the nonleptonic decays we use the factorizing approximation. We update our model parameters by using new experimental data for the mass and the lifetime of the B{sub c} meson and the leptonic decay constants of the D-meson. We calculate the branching ratios for a large set of exclusive nonleptonic and semileptonic decays of the B{sub c} meson and compare our results with the results of other studies. As a guide for further experimental exploration we provide explicit formulas for the full angular decay distributions in the cascade decays B{sub c}{sup -}{yields}J/{psi}({yields}l{sup +}l{sup -})+{rho}{sup -}({yields}{pi}{sup -}{pi}{sup 0}) and B{sub c}{sup -}{yields}J/{psi}({yields}l{sup +}l{sup -})+W{sub off-shell}{sup -}({yields}l{sup -}+{nu}{sub l})

Nonleptonic weak decays of charmed mesons

A previous analysis of two-body Cabibbo-allowed nonleptonic decays of [ital D][sup 0] mesons and of Cabibbo-allowed and first-forbidden decays of [ital D][sup +] and [ital D][sub [ital s]][sup +] has been adjourned using more recent experimental data and extended to the Cabibbo-forbidden decays of [ital D][sup 0]. Annihilation and [ital W]-exchange contributions as well as final state interaction effects (assumed to be dominated by nearby resonances) have been included and are in fact crucial to obtain a reasonable agreement with the experimental data, which show large flavor SU(3) violations. New fitting parameters are necessary to describe rescattering effects for Cabibbo-forbidden [ital D][sup 0] decays, given the lack of experimental information on isoscalar resonances. We keep their number to a minimum, three, using phenomenologically based considerations. We also discuss [ital CP]-violating asymmetries.

The Semileptonic decays of the

We study the semileptonic transitionsBc → �c, J/ , D, D ∗ , B, B ∗ , Bs, B ∗ s in the framework of a relativistic constituent quark model. We use experimental data on leptonic J/ decay, lattice and QCD sum rule results on leptonic Bc decay, and experimental data on radiativec transitions to adjust the quark model parameters. We compute all form factors of the above semileptonic Bc-transitions and give predictions for various semileptonic Bc decay modes including their �-modes when they are kinematically accessible. The impli- cations of heavy quark symmetry for the semileptonic decays are discussed and are shown to be manifest in our explicit relativistic quark model calcu- lation. A comparison of our results with the results of other calculations is performed.

B_c

We evaluate the decays B => K* pi, K (rho,omega,phi) adding the long distance charming penguin contributions to the short distance: Tree+Penguin amplitudes. We estimate the imaginary part of the charming penguin by an effective field theory inspired by the Heavy Quark Effective Theory and parameterize its real part. The final results for branching ratios depend on only two real parameters and show a significant role of the charming penguins. The overall agreement with the available experimental data is satisfactory.

meson

We present calculations of the charming-penguin long-distance contributions to B{r_arrow}K{pi} decays due to intermediate charmed meson states. Our calculation is based on the chiral effective Lagrangian for light and heavy mesons, corrected for the hard pion and kaon momenta. We find that the charming-penguin contributions increase significantly the B{r_arrow}K{pi} decay rates in comparison with the short-distance contributions, giving results in better agreement with experimental data.

Charming penguins in B ---> K* pi, K(rho, omega, phi) decays

Using the covariant constituent quark model previously developed by us we calculate the differential rate and the forward-backward asymmetries on the lepton and hadron side for the rare baryon decays Lambda_b -> Lambda l+ l- (l=e, mu, tau) and Lambda_b -> Lambda gamma. We use helicity methods to write down a three-fold joint angular decay distribution for the cascade decay Lambda_b -> Lambda (-> p pi-) + J_eff (-> l+ l-). Through appropriate angular integrations we obtain expressions for the rates, the lepton-side forward-backward (FB) asymmetry and the polarization of the daughter baryon Lambda leading to a hadron-side forward-backward asymmetry. We present numerical results on these observables using the covariant quark model and compare our results to the results of other calculations that have appeared in the literature.

Charming penguin contributions to B{r_arrow}K{pi}

Abstract We use QCD sum rules to analyze the semileptonic trransition B → πlν in the limit mb → ∞. We derive the dependence of the form factor F1(0) on the heavy quark mass, which is compatible with the expected dependence for the simple role model of F1(q2).We use QCD sum rules to analyze the semileptonic transition

Rare baryon decays Lambda(b) -> Lambda l(+)l(-) (l = e, mu, tau) and Lambda(b) -> Lambda gamma: Differential and total rates, lepton- and hadron-side forward-backward asymmetries

B \to \pi \ell \nu

Dependence of the form factors of B → πℓν on the heavy quark mass

in the limit

Final state interactions for B → VV charmless decays

m_b \to \infty