Comparison of the electromagnetic responses of $^{12}$C obtained from the Green's function Monte Carlo and spectral function approaches

TL;DR

This paper compares electromagnetic responses of carbon from Green's function Monte Carlo and spectral function methods across a range of momentum transfers, assessing their accuracy and applicability limits.

Contribution

It provides a detailed comparison of two computational approaches for nuclear electromagnetic responses, highlighting their respective validity ranges and the importance of relativistic corrections.

Findings

Spectral function approach remains accurate down to 300 MeV.

Relativistic corrections may be significant at 570 MeV in Monte Carlo results.

Spectral function factorization ansatz is reliable at lower momentum transfers.

Abstract

The electromagnetic responses of carbon obtained from the Green's function Monte Carlo and spectral function approaches using the same dynamical input are compared in the kinematical region corresponding to momentum transfer in the range 300-570 MeV. The results of our analysis, aimed at pinning down the limits of applicability of the approximations involved in the two schemes, indicate that the factorization ansatz underlying the spectral function formalism provides remarkably accurate results down to momentum transfer as low as 300 MeV. On the other hand, it appears that at 570 MeV relativistic corrections to the electromagnetic current not included in the Monte Carlo calculations may play a significant role in the transverse channel.