WEAK LEPTONIC DECAY OF LIGHT AND HEAVY PSEUDOSCALAR MESONS IN A FIELD-THEORETIC QUARK-MODEL

Weak leptonic decays of light and heavy pseudoscalar mesons are studie d in a field-theoretic quark model where the mesons are described by c onstituent quarks and antiquarks with a particular ansatz and a Harmon ic oscillator wave function. With constituent quark masses and Harmoni c oscillator radii for mesons as parameters of the model, decay consta nts are calculated and found as (f(pi), f(k), f(D), f(B)) = (132 MeV, 161 MeV, 160 MeV, 115 MeV) indicating a reasonable agreement with the experimental data wherever available. Partial decay widths and branchi ng ratios for kinematically allowed leptonic decay processes are also estimated and compared with the experiments wherever available.