New Precise Measurement of the Pion Weak Form Factors in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>π</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:mo>→</mml:mo><mml:msup><mml:mi>e</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:mi>ν</mml:mi><mml:mi>γ</mml:mi></mml:math>Decay

We have measured the {\ensuremath{\pi}}^{+}\ensuremath{\rightarrow}{e}^{+}\ensuremath{\nu}\ensuremath{\gamma}branching ratio over a wide region of phase space, based on a total of 65 460 events acquired using the PIBETA detector. Minimum-{\ensuremath{\chi}}^{2}fits to the measured ({E}_{{e}^{+}} {E}_{\ensuremath{\gamma}} energy distributions result in the weak form factor value of {F}_{A}=0.0119(1)with a fixed value of...