Speaker
Description
Multi-nucleon (2p2h, two-particle–two-hole) knockout, in which a neutrino interacts with a correlated pair of nucleons inside a nucleus, is a major source of systematic uncertainty in long-baseline neutrino oscillation experiments. One or more outgoing nucleons may fail to exit the nucleus or fall below detector thresholds and thus remain unobserved. These partially reconstructed events can mimic other reaction channels and bias the reconstructed neutrino energy, with direct consequences for oscillation measurements. Most event generators (simulation tools) currently treat this channel with approximate particle kinematics. Recent theoretical developments, however, provide more complete exclusive predictions that expose limitations of these approximations.
This talk presents multi-nucleon knockout mechanisms with an emphasis on two-nucleon emission, and reports the first dedicated analysis of one such exclusive prediction based on the Valencia model. We identify observables whose kinematic distributions deviate most strongly from the approximations used so far and highlight where current simulations can be improved. Finally, we discuss the prospects for making these observables experimentally accessible in current detectors, focusing on ND280 at the T2K experiment, and outline possible paths towards incorporating more realistic multi-nucleon dynamics in future generator implementations.
