CHIRAL LOOP CONTRIBUTION TO D-]K-ASTERISK-LV

Abstract

Light vector mesons are included in the heavy meson chiral Lagrangian in the leading order in momentum expansion. Tree-level form factors in D+ --> K0*BAR e+nu(e) are found at the order of O(k1), and the coefficients of 1/m(Q) terms are fixed by requiring reparametrization invariance of the heavy meson chiral Lagrangian and the weak current. Then, chiral loop contributions [O(k2)] to D --> K*lnu are considered. The imaginary part of the Kpi loop contribution is finite and therefore unambiguously calculable, leading to the lower bounds on the form factors and the partial decay rate in D+ --> K0*BAR e+nu(e). Under a reasonable assumption, one finds g2 < 0.5 is preferred where g is the D*Dpi coupling.