Scale dependence of deuteron electrodisintegration

TL;DR

This paper investigates how the interpretation of deuteron electrodisintegration reactions varies with the renormalization group scale, showing that different resolutions alter the roles of wave functions, currents, and final state interactions, affecting physical intuition.

Contribution

It demonstrates the scale dependence of reaction mechanisms in deuteron electrodisintegration using similarity RG evolution, revealing how intuitive pictures change with resolution.

Findings

FSI are unaffected in some kinematic regions after evolution

Low-resolution evolution simplifies the current representation

Scale dependence affects interpretation of short-range correlations

Abstract

A model calculation of deuteron electrodisintegration is used to explore renormalization group (RG) scale dependence for knock-out reactions. When evolved to different resolutions with the similarity RG (SRG), the initial deuteron wave function, the current operator, and the final state interactions (FSI) are all modified, but how they combine depends strongly on the kinematic region. In some regions, for example, the FSI are largely unaffected by evolution, while elsewhere FSI are greatly reduced. For certain kinematics, the impulse approximation at a high RG resolution gives an intuitive picture in terms of a one-body current breaking up a short-range correlated neutron-proton pair, although FSI distort this simple picture. With evolution to low resolution, however, the cross section is unchanged but a very different and arguably simpler intuitive picture emerges, with the evolved current efficiently represented at low momentum through derivative expansions or low-rank singular value decompositions. A consequence is that intuition about physics such as the role of short-range correlations or $D$-state mixing in particular kinematic regimes can be strongly scale dependent.