Neutrino-Induced Coherent π+ Production in C, CH, Fe, and Pb at ⟨Eν⟩ ∼ 6 GeV

MINERvA has measured the νμ-induced coherent π+ cross section simultaneously in hydrocarbon (CH), graphite (C), iron (Fe), and lead (Pb) targets using neutrinos from 2 to 20 GeV. The measurements exceed the predictions of the Rein-Sehgal and Berger-Sehgal PCAC based models at multi-GeV νμ energies and at produced π+ energies and angles, Eπ>1 GeV and θπ<10°. Measurements of the cross-section ratios of Fe and Pb relative to CH reveal the effective A scaling to increase from an approximate A1/3 scaling at few GeV to an A2/3 scaling for Eν>10 GeV.