V.V. Braguta, A.A. Likhoded, A.E. Chalov

"T-odd correlation in the $K_{l 3 \gamma}$-decay"

 Phys.Rev. D65 (2002) 054038  [hep-ph/0106147] 

      Abstract
  The dependence of the $K^+ \to \pi^0 l^+ \nu_l \gamma$ decay width on the 
$T$-odd kinematical variable, $ \xi = {\vec q \cdot [\vec p_l \times \vec p_ 
\pi]} / {M^3}$, is studied at the tree and one-loop levels of Standard Model. 
It is shown that at the tree level this decay width is the even function of 
$\xi$, while the odd contribution arises due to the electromagnetic final 
state interaction. This contribution is determined by imaginary parts of 
one-loop diagrams. The calculations performed show that the $\xi$-odd 
contribution to the $K^+ \to \pi^0 e^+ \nu_e \gamma$ and 
$K^+ \to \pi^0 \mu^+ \nu_\mu \gamma$ decay widths is four orders of magnitude
smaller than even contribution coming from the tree level of SM. 


 Braguta V.V., Likhoded A.A., Chalov A.E
"Muon transverse polarization in the $K_{l2\gamma}$ process within
the SM and three Higgs doublets Weinberg model"