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Recent developments in the theory of heavy quarks have increased the prospects for the study of non-perturbative QCD in the weak decays of heavy mesons and baryons and for the reliable determination of some of the parameters of the Standard Model. It has been made possible due to the discovery of a spin-flavour symmetry for heavy quarks which arises in QCD when quark mass is taken to infinity. Certain properties in hadrons containing a heavy quark then become independent of its mass and spin. These ideas have tremendous impact on the phenemenology of heavy hadrons. In particular, these symmetries give rise to restrictive relations among weak decay amplitudes and reduce the number of independent form factors. By relating various matrix elements and fixing normalization of some matrix elements, the heavy quark symmetry has enhanced our predictive ability, allowing in some cases to bypass the difficulties of understanding hadronic structure.

M P Khanna¹

1. Centre of Advanced Study in Physics, Department of Physics, Panjab University, Chandigarh - 160 014, India

Published

July 1993