arXiv subjects
Publications and source records attributed to R. C. Verma.
We study two-body weak hadronic decays of ψand Upsilon employing the factorization scheme. Branching ratios for ψ-> PP/PV and Υ-> PP/PV decays in the Cabibbo-angle-enhanced and Cabibbo-angle-suppressed modes are predicted.
We study two-body weak decays of charmed baryons Λ_c and Ξ_c into an octet or decuplet baryon and a pseudoscalar meson employing the SU(3) flavor symmetry. Using certain measured Cabibbo-favored modes, we fix the reduced amplitudes and predict the branching ratios of various decays of charmed baryons in the Cabibbo-enhanced, -suppressed and -doubly suppressed modes.
Weak decays of heavy flavor hadrons play a special role in our understanding of physics of the Standard Model and beyond. The measured quantities, however, result from a complicated interplay of weak and strong interactions. Weak leptonic and semileptonic decays are reasonably well understood, whereas weak hadronic decays present challenges to theory. In this talk, we review the present status of exclusive weak decays of charm and bottom hadrons.
We investigate nonfactorizable contributions to two-body hadronic decays of the charmed mesons to a pseudoscalar meson and a vector meson in Cabibbo-favored mode. Employing SU(3)-flavor symmetry for the nonfactorizable matrix elements, we obtain branching ratios of the decays in consistent agreement with experiment.
We study charm D - meson decays to two pseudoscalar mesons in Cabibbo favored mode employing SU(3)-flavor for the nonfactorizable matrix elements. Using $D\rightarrow \bar K π$ and $D_{s} \rightarrow \bar K K$ to fix the reduced matrix elements, we obtain a consistent fit for $ η$ and $ η'$ emitting decays of $D$ and $ D_{s}$ mesons.
The two body Cabibbo favored hadronic decays of charmed baryons $Λ^{+}_{c}$, $Ξ^{+}_{c}$ and $Ξ_{c}^{0}$ into an octet or decuplet baryon and a pseudoscalar meson are examined in the SU(3) symmetry scheme. The numerical estimates for decay widths and branching ratios of some of the modes are obtained and are in good agreement with experiment.
We investigate nonfactorizable contributions to charm meson decays in $ D \rightarrow \bar K π$/ $ \bar K ρ$ /$ \bar K ^{*} π$ / $ \bar K a_{1}$ / $ \bar K ^{*} ρ$ modes. Obtaining the contributions from spectator-quark diagrams for $ N_{c}$ = 3, we determine nonfactorizable isospin 1/2 and 3/2 amplitudes required to explain the data for these modes. We observe that ratio of these amplitudes seem to follow a universal value.
With the inclusion of nonfactorized amplitudes in a scheme with $N_c=3$, we have studied Cabibbo-favored decays of $D^0$ and $D^+$ into two-body hadronic states involving two isospins in the final state. We have shown that it is possible to understand the measured branching ratios and determined the sizes and signs of nonfactorized amplitudes required.
According to the Coleman-Glashow null theorem if all the symmetry breaking effects belong to the same regular representation (octet in the case of SU(3) and {\bf 15} in the case of SU(4)) and are generated in a tadpole type mechanism, the strangeness changing (charm changing) weak transitions generated through the S$_{6}$ (S$_{9}$) tadpole must vanish. Exploiting this null result, we find relations between the BBP coupling constants which allow us to write the coupling constants in terms of two parameters and baryon masses. Fixing these two parameters ( $g_{NNπ}$ and $g_{ΛΣπ}$) from experiments, we estimate the remaining coupling constants.