$K^+_{l3\gamma}$ decays revisited: branching ratios and T-odd momenta correlations

Understand

We calculate the branching ratios of the $K^+ \to \pi^0 l^+ \nu_l\gamma (l = e, \mu)$ decays, and the T-odd triple momenta correlations $\xi=\vec{q}\cdot[\vec{p}_l \times \vec{p}_\pi]/M^3_K$, due to the electromagnetic final state interaction, in these processes.

• The contributions on the order of $\omega^{-1}$ and $\omega^0$ to the corresponding amplitudes are treated exactly.
• For the branching ratios, the corrections on the order of $\omega$ are estimated and demonstrated to be small.
• We compare the results with those of other authors.