On the term of the 4-th order with respect to the field operators in the translation-invariant polaron theory

TL;DR

This paper demonstrates that the fourth-order term in the translation-invariant polaron theory is zero, simplifying the theoretical framework and potentially impacting related calculations.

Contribution

It proves that the fourth-order term with respect to field operators in the translation-invariant polaron theory vanishes, a novel theoretical insight.

Findings

Fourth-order term in the theory vanishes

Simplifies the mathematical structure of the theory

Impacts future calculations in polaron models

Abstract

It is shown that 4-th order term in the translation-invariant polaron theory vanishes.