$K_{e3}$ decay studies in the OKA experiment

Recent results from OKA setup concerning form factor studies in $K_{e3}$ decay are presented. About $5.25$ M events obtained for decays of $17.7$ GeV/$cK^+$ are selected for the analysis. The linear and quadratic slopes for the decay form factor $f_+(t)$ are measured: $\lambda_{+}=(2.95 \pm 0.022 \pm 0.018 )\times 10^{-2}$ for the linear slope fit and $\lambda'_{+}=(2.611 \pm 0.035 \pm 0.028 )\times 10^{-2}$, $\lambda''_{+}=(1.91 \pm 0.19 \pm 0.14)\times 10^{-3}$ for the quadratic one. The scalar and tensor contributions are compatible with zero. Several alternative parametrizations are tried: the Pole fit parameter is found to be $M_V = 891 \pm 3$ MeV; the parameter of the dispersive parametrization is measured to be $\Lambda_+ =(2.458 \pm 0.018) \times 10^{-2}$.