Quantum stability in open string theory with broken supersymmetry

H Partouche

doi:10.1088/1742-6596/1586/1/012036

Abstract

We consider the 1-loop effective potential in type I string theory compactified on a torus, with supersymmetry broken by the Scherk-Schwarz mechanism. At fixed supersymmetry breaking scale M, and up to exponentially suppressed terms, we show that the potential admits local minima of arbitrary sign, in dimension d ≤ 5. While the open string Wilson lines are massive, the closed string moduli are flat directions. In a T-dual picture, the relevant backgrounds involve isolated ½-branes, whose positions are frozen on orientifold planes, thus decreasing the rank of the gauge group, and introducing massless fermions in fundamental representations.

Highlights

In string theory, when supersymmetry is spontaneously broken in flat space at a scale M moderately smaller than the string scale Ms, the effective potential simplifies greatly and the questions of its sign, magnitude and stability at extrema can be addressed is a systematic way
Note that because of the underlying extended supersymmetry, all moduli fields can be interpreted as Wilson lines (WLs), but we find convenient to use this denomination for all moduli fields except the so-called no-scale modulus M [3]
-branes coincident on a single orientifold plane yields the lowest value nF − nB = −8 × 504, and it is stable with respect to all open string WLs in arbitrary dimension d

Summary

Introduction

In string theory, when supersymmetry is spontaneously broken in flat space at a scale M moderately smaller than the string scale Ms, the effective potential simplifies greatly and the questions of its sign, magnitude and stability at extrema can be addressed is a systematic way. Where ξd > 0 captures the contributions of the KK modes [4] At such a point in moduli space, the potential is critical with respect to the WLs, as follows from the enhancement of the massless spectrum (no Higgs-like scale between 0 and M). The point is that the higher V is (due to the presence of massless fermions), the more unstable the background is, as follows from dangerous contributions arising from the massless fermions charged under the gauge group i.e. coupled to the WLs. In the present work, we review the fact that stable backgrounds exist, while satisfying V ≥ 0 [1]. We review the fact that stable backgrounds exist, while satisfying V ≥ 0 [1] Note that such models may be relevant in several respects. -branes with positions frozen on orientifold planes play a crucial role, since (i) they do not yield marginal deformations that may be tachyonic, (ii) they decrease the dimension of the gauge group, lowering nB, (iii) and they yield massless fermionic strings stretched between them and other branes, due to the interplay between WL deformations and Scherk-Schwarz mechanism

Wilson line stability in 9 dimensions

Wilson line stability and positive potential in d dimensions

Conclusion and remarks