We investigate the form factors and decay rates for the semileptonic decays of the kaon($K_{ l3})$ using the light-front quark model. The form factors $f_{ \pm}(q^{ 2})$ are calculated in $q^{ +}=0$ frame and analytically continued to the time-like region, $q^{ 2}>0$. Our numerical results for the physical observables, $f_{ -}/f_{ +}|_{ q^{ 2}=m^{ 2}_{ l}}=-0.38$, $\lambda_{ +}=0.025$(the slope of $f_{ +}$ at $q^{ 2}=m^{ 2}_{ l}$), $\Gamma(K^{ 0}_{ e3})=(7.30\pm 0.12)\times10^{ 6}s^{ -1}$, and $\Gamma(K^{ 0}_{ \mu3})=(4.57\pm0.07)\times10^{ 6}s^{ -1}$ are quite comparable with the experimental data and other theoretical model calculations. The non-valence contributions from $q^{ +}\neq 0$ frame are also estimated.
Categories: hep-ph