Mass Spectroscopy Leptonic And Radiative Transitions Of Heavy-light Quarkonia In Framework Of Bethe-salpeter Equation

In this thesis, we use the QCD motivated Bethe-Salpeter Equation (BSE) framework for massrnspectral calculations of ground and excited states of 0++ (S), 0À€€+ (P), and 1ð€€€ð€€€(V) heavy-light asrnwell as equal mass quarkonia by making use of the exact treatment of the spin part (_ _) ofrnthe interaction kernel. This work is a substantial improvement over earlier works on equal massrnquarkonia in the sense that we have used all Dirac structures contributing in hadronic Bethe-rnSalpeter wave function for the calculation of mass spectra and leptonic decay constants of heavylightrnquarkonia. In this 4 _ 4 BSE framework, the coupled integral equations obtained for heavylightrnmesons through Salpeter equations are much more involved than the corresponding equationsrnof equal mass (QQ) mesons. These equations are first shown to decouple for the confining partrnof interaction, under heavy-quark approximation, and analyically solved, and later the one-gluonexchangerninteraction is perturbatively incorporated, leading to their mass spectral equations, whichrnwere also used to calculate the algebraic forms of wave functions of various states of 0++; 0ð€€€+,rnand 1ð€€€ð€€€ heavy-light quarkonia in an approximate harmonic oscillator basis. We have then usedrnthe analytic forms of wave functions obtained from these equations to calculate leptonic decayrnconstants of ground and excited states of 0ð€€€+, and 1ð€€€ð€€€. We have further calculated the singlernphoton radiative decay widths for M1 transitions, V ! P, and E1 transitions, V ! S, andrnS ! V , as a test of the wave functions and the BSE framework. The results of decay widths arernin reasonable agreement with data and other models.

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