Comment on "Relativistic covariance and nonlinear quantum mechanics: Tomonaga-Schwinger analysis''

TL;DR

This paper refutes a previous claim by demonstrating that the Tomonaga-Schwinger equation remains covariant even with nonlinear modifications, clarifying misconceptions and correcting earlier errors.

Contribution

It provides a corrected proof showing the covariance of the Tomonaga-Schwinger equation under nonlinear modifications, addressing and fixing errors in prior work.

Findings

The Tomonaga-Schwinger equation is covariant with nonlinear modifications.

Previous claims of non-covariance were based on errors and loopholes.

The corrected proof simplifies understanding of covariance in nonlinear quantum mechanics.

Abstract

Contrary to the central claim (Hsu, 2026) published in Physics Letters B, the Tomonaga--Schwinger equation remains covariant despite the nonlinear modification of it. The proof of covariance becomes simple after the loopholes and mistakes in Hsu's arguments are identified.