Quasielastic lepton scattering and back-to-back nucleons in the short-time approximation

TL;DR

This paper introduces a new short-time approximation method for calculating the nuclear response to quasielastic lepton scattering, effectively capturing two-nucleon dynamics and correlations crucial for interpreting electron and neutrino scattering experiments.

Contribution

The paper presents a novel approach based on realistic nuclear models to evaluate inclusive and exclusive responses, including back-to-back nucleons, with improved treatment of correlations and currents.

Findings

Initial- and final-state correlations are essential for accurate response modeling.

Two-nucleon currents significantly influence the quasielastic response.

The method can be extended to include relativistic effects and resonance regions.

Abstract

Understanding quasielastic electron- and neutrino-scattering from nuclei has taken on new urgency with current and planned neutrino oscillation experiments, and with electron scattering experiments measuring specific final states, such as those involving nucleon pairs in ``back-to-back'' configurations. Accurate many-body methods are available for calculating the response of light ($A \leq 12$) nuclei to electromagnetic and weak probes, but they are computationally intensive and only applicable to the inclusive response. In the present work we introduce a novel approach, based on realistic models of nuclear interactions and currents, to evaluate the short-time (high-energy) inclusive and exclusive response of nuclei. The approach accounts reliably for crucial two-nucleon dynamics, including correlations and currents, and provides information on back-to-back nucleons observed in electron and neutrino scattering experiments. We demonstrate that in the quasielastic regime and at moderate momentum transfers both initial- and final-state correlations, and two-nucleon currents are important for a quantitatively successful description of the inclusive response and final state nucleons. Finally, the approach can be extended to include relativistic---kinematical and dynamical---effects, at least approximately in the two-nucleon sector, and to describe the response in the resonance-excitation region.