Probing naked singularities in non-supersymmetric string vacua

Abstract

We present a detailed analysis of non-supersymmetric spacetime varying string vacua which can lead to an exponential hierarchy between the electroweak and the gravitational scales. In particular, we identify a limit in which these vacua can be interpreted as supersymmetric vacua of F-theory. Furthermore, we study the properties of these solutions as seen by D7-brane probes and establish a non-supersymmetric analogue of the enhançon mechanism.

Graviton absorption by non-BPS branes

“…Perhaps this is the supergravity way of observing that at short distances the predominant features of non-BPS branes spring from open string excitations. This suggests a possible resolution of the naked singularity by a non-supersymmetric enhançon mechanism [18,19] whereby the ρ ≤ r 0 region is smoothed out while the ρ ≥ r 0 remains unchanged.…”

On stringy de Sitter spacetimes

“…In particular, we will focus on a class of models arising from type IIB/F-theory, the so called 'axilaton' models 1 [12][13][14][15][16][17]: (1) evade the oft-mentioned no-go theorem 2 [19][20][21][22], (2) form a discretuum owing to their stringy SL(2; Z) monodromy, (3) the overall lengthscale is determined by dimensional transmutation, (4) require g s ∼ O (1), with an effective incorporation of S-duality, and (5) relate two classes of standard supersymmetric string theory solutions [23,24] and [25], and a third, novel class. This resonates with some recent assessments [26], and some features of the recent efforts [27,28]; it reminds of the "T-fold" constructions [29][30][31][32], and qualifies the standard low-energy effective theory limit description as encouraging but incomplete: more of the stringy degrees of freedom must be included, as also advocated recently in the phase-space approach [33][34][35][36][37][38][39][40][41], and also in the different, earlier double field theory approach [42][43][44][45][46].…”

The enhançon and the consistency of excision

“…Refs [16]. provide other opportunities to apply the techniques discussed here to non-supersymmetric cases…”