Charge form factor and sum rules of electromagnetic response functions in Carbon-12

TL;DR

This paper presents an ab initio calculation of Carbon-12's electromagnetic form factors and response sum rules, highlighting the importance of two-body currents and their potential impact on neutrino scattering anomalies.

Contribution

It provides the first ab initio calculations of these response functions using realistic nuclear potentials and currents, emphasizing the role of two-body currents in the transverse response.

Findings

Longitudinal form factor agrees with experimental data.

Transverse sum rule shows large contributions from two-body currents.

Implications for neutrino scattering anomalies are discussed.

Abstract

An "ab initio" calculation of the Carbon-12 elastic form factor, and sum rules of longitudinal and transverse response functions measured in inclusive (e,e') scattering, is reported, based on realistic nuclear potentials and electromagnetic currents. The longitudinal elastic form factor and sum rule are found to be in satisfactory agreement with available experimental data. A direct comparison between theory and experiment is difficult for the transverse sum rule. However, it is shown that the calculated one has large contributions from two-body currents, indicating that these mechanisms lead to a significant enhancement of the quasi-elastic transverse response. This fact may have implications for the anomaly observed in recent neutrino quasi-elastic charge-changing scattering data off Carbon-12.