D-branes in Melvin Background

TL;DR

This paper investigates D-branes in Melvin backgrounds, constructing boundary states and analyzing how their spectra depend on the rationality of magnetic flux, revealing connections to fractional D-branes and noncommutative geometry.

Contribution

It explicitly constructs D-brane boundary states in Melvin backgrounds, exploring their spectra and supersymmetry properties based on flux rationality, linking to fractional branes and noncommutative geometry.

Findings

D-brane spectra depend on magnetic flux rationality

Rational flux yields fractional D-brane generalizations

Irrational flux results in a limited D-brane spectrum

Abstract

In this paper we discuss D-branes in the Melvin background and its supersymmetric generalizations. In particular we determine the D-brane spectra in these backgrounds by constructing their boundary states explicitly, where some of the D-branes are supersymmetric. The results sensitively depend on whether the value of magnetic flux in the Melvin background is rational or irrational. For the rational case the D-branes are regarded as the generalizations of fractional D-branes in abelian orbifolds ${\bf C^n/Z_N}$ of type II or type 0 string theory. For the irrational case we found a very limited spectrum. Since the background includes the nontrivial H-flux, the D-branes will provide interesting examples from the viewpoint of the noncommutative geometry.