Calculation of doubly heavy baryons decay

We calculated a subclass of four nonleptonic two-body weak decays of the double charm baryon ground states Ξcc++. Nonleptonic decays can be dividedinto two group: factorizable and nonfactorizable decays. The first one can be easily calculated from first principles. Therefore, its good example understands all pros and cons of a model. We focused on a weak two-body nonleptonic decay consists only fromthe factorizing contribution precluding a contamination from W-exchange. We use the covariant confined quark model previously developed by us to calculate the various helicity amplitudes which describe the dynamics of the transition induced by the Cabibbo-favored effective currents. Achievement of CCQM is that only size parameter Λvarying can describe all tree diagrams of nonleptonic decay. We then proceed to calculate the rates of the decay. The rates, branching ratios and helicity amplitude were calculated using dimensionless invariant form factors. Also, we calculated leptonic constant for scalar and vector mesons which has good agreement with experimental data. There isn’t any experimental data about the decay so we waiting for new experimental observation in the heavy baryon sector.

ON NONLEPTONIC Σ+ → pπ0 DECAY IN THE EFFECTIVE QUARK MODEL WITH CHIRAL U(3) × U(3) SYMMETRY

Within the effective quark model with chiral U (3) × U (3) symmetry we calculate the S-wave and P-wave amplitudes of the nonleptonic decay Σ+ → pπ0, the partial width and the dynamical polarization of the proton in the dependence on the polarization of the Σ+-hyperon. The theoretical results agree well with the experimental data.

POLARIZED HEAVY BARYON DECAYS

We calculate the amplitudes involved in the heavy baryon nonleptonic decay Λb → ΛJ/ψ using perturbative QCD factorization theorem, which are expressed as convolutions of hard b quark decay amplitudes with the Λb baryon, Λ baryon and J/ψ meson distribution amplitudes. It is found that nonfactorizable contributions dominate over factorizable ones. Employing the distribution amplitudes determined in our previous works, we derive the branching ratio B(Λb → ΛJ/ψ) = (1.65 ~ 5.27) × 10-4 in agreement with data. We predict an asymmetry parameter α = -0.17 ~ -0.14 associated with the anisotropic angular distribution of the Λ baryons produced in polarized Λb baryon decays.

SECOND ORDER QCD CORRECTIONS TO THE NONLEPTONIC DECAY OF THE b QUARK IN THE SLOW CHARM LIMIT

The perturbative QCD corrections to the nonleptonic decay rate of the b quark are discussed. By considering the limit where the final charmed quarks are slow, it is argued that the coefficients of the [Formula: see text] terms, corresponding to the next-to-next-to-leading order in the standard renormalization group expansion in ln (mW/mb), are naturally large. The large coefficients arise from the final state gluon exchange between quarks and are associated with the region of rather low momenta, which may further enhance the phenomenological significance of these terms.

FINAL STATE INTERACTIONS AND PREASYMPTOTIC EFFECTS IN NONLEPTONIC KAON DECAYS

Nonleptonic decay rates of [Formula: see text] and K− have been estimated using the two independent theoretical schemes. With final state interactions of emitted pions included, both schemes yield qualitatively a correct and consistent description of decay rates. Various contributions to decay rates have also been estimated. It turns out that contributions due to the quark annihilation mechanisms are much larger than the decay term, contrary to the usual beliefs based on helicity arguments.