Electroproduction of soft pions at high $Q^2$ near the threshold from CLAS

Threshold pion electoproduction has long been a topic of interest for both experimental and theoretical studies. In {\em chiral symmetry}, the approximately zero pion mass allows one to make exact predictions for threshold cross sections using {\em low energy theorems} (LET). The LET established the connection between charged pion electroproduction and the axial form factor in the nucleon. Thanks to studies based on the light-cone sum rules (LCSR), one can calculate the hadron form factors in terms of distribution amplitudes that approach perturbative quantum chromodynamics (pQCD) without other non-perturbative parameters. The extraction of the axial form factor near the pion threshold is dominated by the S- wave multipole $E_{0+}$ in the LCSR framework~[VBraun08]. Preliminary extracted axial form factor close to the threshold region will be presented. This analysis is based on the exclusive electroproduction process $ep \to e'n\pi^+$,~[KPark08] which was measured in the interval of $Q^2$ from $2.0$ to $4.5~\rm{GeV^2}$, and an invariant mass range in the $n\pi^+$ system from $W = 1.11$ to $1.15~\rm{GeV}$. The CEBAF Large Acceptance Spectrometer (CLAS) was used to carry out these measurement.