Effective Field Theory for Noncommutative Spacetime: A Toy Model

TL;DR

This paper introduces a geometric toy model of a noncommutative plane that captures key features of noncommutative spacetime physics, revealing internal angular momentum, spin of particles, and stringy signatures within a field theory framework.

Contribution

It presents a novel geometric model demonstrating noncommutative spacetime features through internal constraints, linking noncommutative and ordinary field theories as gauge equivalent.

Findings

Elementary excitations exhibit stringy signatures like dipolar nature.

Noncommutative and ordinary field theories are gauge equivalent.

Classical analysis shows subtlety in Nambu-Goto and Polyakov formulations.

Abstract

A novel geometric model of a noncommutative plane has been constructed. We demonstrate that it can be construed as a toy model for describing and explaining the basic features of physics in a noncommutative spacetime from a field theory perspective. The noncommutativity is induced internally through constraints and does not require external interactions. We show that the noncommutative space-time is to be interpreted as having an {\it internal} angular momentum throughout. Subsequently, the elementary excitations - {\it i.e.} point particles - living on this plane are endowed with a {\it spin}. This is explicitly demonstrated for the zero-momentum Fourier mode. The study of these excitations reveals in a natural way various {\it stringy} signatures of a noncommutative quantum theory, such as dipolar nature of the basic excitations \cite{jab} and momentum dependent shifts in the interaction point \cite{big}. The observation \cite{sw} that noncommutative and ordinary field theories are alternative descriptions of the same underlying theory, is corroborated here by showing that they are gauge equivalent. Also, treating the present model as an explicit example, we show that, even classically, in the presence of additional constraints, (besides the usual ones due to reparameterization invariances), the equivalence between Nambu-Goto and Polyakov formulations is subtle.