# Refractive index and generalized polarizability

## TL;DR

This paper explores how retardation effects influence polarizability and refractive index, emphasizing the need for nonlocal dielectric models in interpreting precise optical measurements.

## Contribution

It introduces the importance of nonlocal dielectric constant modifications due to retardation corrections in classical electromagnetic theory.

## Key findings

- Retardation corrections significantly affect polarizability and refractive index.
- Nonlocal dielectric models are necessary for accurate optical measurements.
- Classical theory requires modifications to incorporate nonlocal effects.

## Abstract

We investigate the role of retardation corrections to polarizability and to refractive index. We found that the classical electromagnetic theory of dielectrics requires corresponding modifications in terms of nonlocality of the dielectric constant. This nonlocality should be taken into account in the interpretation of accurate measurements of the optical refractivity.