T-odd correlation in the Kl3γ decay

The dependence of the K+ --> pi(0)l(+)v(l)gamma decay rate on the T-odd kinematical variable xi = q . [p(l) x p(pi)]/m(K)(3) is investigated in the tree and one-loop approximations of the Standard Model (SM). It K is shown that the partial width of the decay on the tree level is an even function of the variable xi, whereas the odd component is generated by the electromagnetic final-state interaction and determined by the imaginary parts of one-loop diagrams. The xi-odd components of the partial widths of the K+--> pi(0)e(+)v(e)gamma and K+--> pi(0)mu(+)v(mu)gamma decays calculated in the one-loop approximation are smaller by four orders of magnitude than the even components evaluated from the tree-level SM diagrams. (C) 2002 MAIK Nauka/Interperiodica.