First measurement of the muon antineutrino double-differential charged-current quasielastic cross section

The largest sample ever recorded of (nu) over bar (mu) charged-current quasielastic (CCQE, (nu) over bar (mu) + p -> mu(+) + n) candidate events is used to produce the minimally model-dependent, flux-integrated double-differential cross section d(2)sigma/dT(mu) d cos theta(mu) for (nu) over bar (mu) CCQE for a mineral oil target. This measurement exploits the large statistics of the MiniBooNE antineutrino mode sample and provides the most complete information of this process to date. In order to facilitate historical comparisons, the flux-unfolded total cross section sigma(E-nu) and single-differential cross section d sigma/dQ(2) on both mineral oil and on carbon are also reported. The observed cross section is somewhat higher than the predicted cross section from a model assuming independently acting nucleons in carbon with canonical form factor values. The shape of the data are also discrepant with this model. These results have implications for intranuclear processes and can help constrain signal and background processes for future neutrino oscillation measurements.