First Measurement of the Charged Current $overline{ u}_{mu}$ Double Differential Cross Section on a Water Target without Pions in the final state

This paper reports the first differential measurement of the charged-current $overline{ u}_{mu}$ interaction cross section on water with no pions in the final state. The unfolded flux-averaged measurement using the T2K off-axis near detector is given in double differential bins of $mu^+$ momentum and angle. The integrated cross section in a restricted phase space is $sigma=left(1.11pm0.18right)times10^{-38}$ cm$^{2}$ per water molecule. Comparisons with several nuclear models are also presented.