The phases of 2D NCOS

TL;DR

This paper investigates the phase structure of 1+1 dimensional non-commutative open string theory on a circle, revealing how non-commutativity scale and stringy behavior depend on coupling and charge, with implications for UV-IR mixing.

Contribution

It provides a detailed analysis of the phase transitions and geometric features of 2D NCOS, including the behavior of non-commutativity and the near horizon geometry at different couplings.

Findings

Non-commutativity length scale increases with strong coupling.

System exhibits stringy behavior at a specific length scale.

Near horizon geometry shows UV-IR mixing effects.

Abstract

We study the phases of the 1+1 dimensional Non-Commutative Open String theory on a circle. We find that the length scale of non-commutativity increases at strong coupling, the coupling in turn being dressed by a power of D-string charge. The system is stringy at around this length scale, with dynamics involving an interplay between the open and wrapped closed strings sectors. Above this energy scale and at strong coupling, and below it at weak coupling, the system acquires a less stringy character. The near horizon geometry of the configuration exhibits several intriguing features, such as a flip in the dilaton field and the curvature scale, reflecting UV-IR mixing in non-commutative dynamics. Two special points in the parameter measuring the size of the circle are also identified.