Remarks on Time-Space Noncommutative Field Theories

TL;DR

This paper interprets the unitarity breakdown in time-like noncommutative field theories as tachyonic particle production, linking string theory remnants to field theory issues and analyzing their locality and causality properties.

Contribution

It offers a unified string-theoretic and field-theoretic perspective on the problems of time-like noncommutative theories and studies their quantum locality and causality features.

Findings

Unitarity breakdown linked to tachyonic particle production.

Remnants of closed-string modes influence noncommutative field theories.

Quantum analysis of locality and causality properties.

Abstract

We propose a physical interpretation of the perturbative breakdown of unitarity in time-like noncommutative field theories in terms of production of tachyonic particles. These particles may be viewed as a remnant of a continuous spectrum of undecoupled closed-string modes. In this way, we give a unified view of the string-theoretical and the field-theoretical no-go arguments against time-like noncommutative theories. We also perform a quantitative study of various locality and causality properties of noncommutative field theories at the quantum level.