Non-supersymmetric Vacua Research Articles

META-STABLE BRANE CONFIGURATIONS WITH MULTIPLE NS5-BRANES

Starting from an [Formula: see text] supersymmetric electric gauge theory with the multiple product gauge group and the bifundamentals, we apply Seiberg dual to each gauge group, obtain the [Formula: see text] supersymmetric dual magnetic gauge theories with dual matters including the gauge singlets. Then we describe the intersecting brane configurations, where there are NS-branes and D4-branes (and anti-D4-branes), of type IIA string theory corresponding to the meta-stable nonsupersymmetric vacua of this gauge theory. We also discuss the case where the orientifold 4-planes are added into the above brane configuration. Next, by adding an orientifold 6-plane, we apply to an [Formula: see text] supersymmetric electric gauge theory with the multiple product gauge group (where a single symplectic or orthogonal gauge group is present) and the bifundamentals. Finally, we describe the other cases where the orientifold 6-plane intersects with NS-brane.

META-STABLE BRANE CONFIGURATIONS OF TRIPLE PRODUCT GAUGE GROUPS

From an [Formula: see text] supersymmetric electric gauge theory with the gauge group [Formula: see text] with fundamentals for each gauge group and the bifundamentals, we apply Seiberg dual to each gauge group and obtain the [Formula: see text] supersymmetric dual magnetic gauge theories with dual matters including the additional gauge singlets. By analyzing the F-term equations of the dual magnetic superpotentials, we describe the intersecting brane configurations of type IIA string theory corresponding to the meta-stable nonsupersymmetric vacua of this gauge theory. We apply also to the case for [Formula: see text] supersymmetric electric gauge theory with the gauge group [Formula: see text] with flavors for each gauge group and the bifundamentals. Finally, we describe the meta-stable brane configurations of multiple product gauge groups.

META-STABLE BRANE CONFIGURATIONS OF MULTIPLE PRODUCT GAUGE GROUPS WITH ORIENTIFOLD 6 PLANE

Starting from an [Formula: see text] supersymmetric electric gauge theory with the gauge group [Formula: see text] with fundamentals for each gauge group, the bifundamentals, a symmetric flavor and a conjugate symmetric flavor for SU (Nc), we apply Seiberg dual to each gauge group, obtain the [Formula: see text] supersymmetric dual magnetic gauge theories with dual matters including the gauge singlets, and describe the intersecting brane configurations of type IIA string theory corresponding to the meta-stable nonsupersymmetric vacua of this gauge theory. We also discuss the case where a symmetric flavor is replaced by an antisymmetric flavor. Next we apply to the case for [Formula: see text] supersymmetric electric gauge theory with the gauge group [Formula: see text] with flavors for each gauge group and the bifundamentals. Finally, we describe the case where the orientifold 6-plane charge is reversed.

Open string wavefunctions in warped compactifications

We analyze the wavefunctions for open strings in warped compactifications, and compute the warped Kähler potential for the light modes of a probe D-brane. This analysis not only applies to the dynamics of D-branes in warped backgrounds, but also allows to deduce warping corrections to the closed string Kähler metrics via their couplings to open strings. We consider in particular the spectrum of D7-branes in warped Calabi-Yau orientifolds, which provide a string theory realizations of the Randall-Sundrum scenario. We find that certain background fluxes, necessary in the presence of warping, couple to the fermionic wavefunctions and qualitatively change their behavior. This modified dependence of the wavefunctions are needed for consistency with supersymmetry, though it is present in non-supersymmetric vacua as well. We discuss the deviations of our setup from the RS scenario and, as an application of our results, compute the warping corrections to Yukawa couplings in a simple model. Our analysis is performed both with and without the presence of D-brane world-volume flux, as well as for the case of backgrounds with varying dilaton.

Nonsupersymmetric brane vacua in stabilized compactifications

We derive the equations for the nonsupersymmetric vacua of D3-branes in the presence of nonperturbative moduli stabilization in type IIB flux compactifications, and solve and analyze them in the case of two particular 7-brane embeddings at the bottom of the warped deformed conifold. In the limit of large volume and long throat, we obtain vacua by imposing a constraint on the 7-brane embedding. These vacua fill out continuous spaces of higher dimension than the corresponding supersymmetric vacua, and have negative effective cosmological constant. Perturbative stability of these vacua is possible but not generic. Finally, we argue that -branes at the tip of the conifold share the same vacua as D3-branes.

Type IIB flux vacua at large complex structure

We study models of stabilization near large complex structure in type IIB O3/O7 flux compactifications. We consider a special family of examples with a single nonvanishing Yukawa coupling in the large complex structure limit, which allows us to study all possible stable vacua of the tree-level no-scale potential very explicitly. We find that, by tuning fluxes, both supersymmetric and nonsupersymmetric vacua can be realized at almost any point in the large complex structure moduli space of one-, two-, and three-parameter models. We also consider the effects of stringy corrections on tree-level vacua. We argue quite generally that, in certain regimes, both supersymmetric and nonsupersymmetric tree-level vacua could serve as consistent, controllable foundations for full stabilization beyond tree level (including Kahler moduli), leading to either AdS or dS cosmological constants. We show how to achieve these regimes in our models. Finally, we discuss some implications of minimizing at tree level the no-scale form of the scalar potential, versus other potentials used in statistical studies.

Other meta-stable brane configuration by adding an orientifold 6-plane to Giveon–Kutasov

Giveon and Kutasov have found the type IIA intersecting nonsupersymmetric meta-stable brane configuration where the electric gauge theory superpotential has a quartic term as well as the mass term for quarks. In this Letter, by adding the orientifold 6-plane to this brane configuration, we describe the brane configuration corresponding to the meta-stable nonsupersymmetric vacua of the supersymmetric unitary gauge theory with symmetric flavor as well as fundamental flavors.

O'Raifeartaigh models with spontaneous R-symmetry breaking

O'Raifeartaigh models can have non-supersymmetric vacua with broken R-symmetry if they contain fields with R-charges different from 0 and 2. Runaway directions often occur in these models. We outline the relation between these runaway directions and R-symmetry.

Geometrically induced phase transitions at largeN

Utilizing the large N dual description of a metastable system of branes and anti-branes wrapping rigid homologous S^2's in a non-compact Calabi-Yau threefold, we study phase transitions induced by changing the positions of the S^2's. At leading order in 1/N the effective potential for this system is computed by the planar limit of an auxiliary matrix model. Beginning at the two loop correction, the degenerate vacuum energy density of the discrete confining vacua split, and a potential is generated for the axion. Changing the relative positions of the S^2's causes discrete jumps in the energetically preferred confining vacuum and can also obstruct direct brane/anti-brane annihilation processes. The branes must hop to nearby S^2's before annihilating, thus significantly increasing the lifetime of the corresponding non-supersymmetric vacua. We also speculate that misaligned metastable glueball phases may generate a repulsive inter-brane force which stabilizes the radial mode present in compact Calabi-Yau threefolds.

More on meta-stable brane configuration by quartic superpotential for fundamentals

For the case where the gauge theory superpotential has a quartic term as well as the mass term for quarks, the nonsupersymmetric meta-stable brane configuration was found recently. By adding the orientifold 6-planes and the extra fundamental flavors to this brane configuration, we describe the meta-stable nonsupersymmetric vacua of the gauge theory with antisymmetric flavor as well as fundamental flavors in type IIA string theory.

Supersymmetric QCD vacua and geometrical engineering

We consider the geometrical engineering constructions for the $N=1$ supersymmetric QCD vacua recently proposed by Giveon and Kutasov. After 1 T-duality, the geometries with wrapped D5 branes become $N=1$ brane configurations with NS branes and D4 branes. The field theories encoded by the geometries contain extra massive adjoint fields for the flavor group. After performing a flop, the geometries contain branes, antibranes and branes wrapped on nonholomorphic cycles. The various tachyon condensations between pairs of wrapped D5 branes and anti-D5 branes together with deformations of the cycles give rise to a variety of supersymmetric and metastable nonsupersymmetric vacua.

Mirrorfolds with K3 fibrations

We study a class of non-geometric string vacua realized as completely soluble superconformal field theory (SCFT). These models are defined as `interpolating orbifolds' of K3 × S1 by the mirror transformation acting on the K3 fiber combined with the half-shift on the S1-base. They are variants of the T-folds, the interpolating orbifolds by T-duality transformations, and thus may be called `mirrorfolds'. Starting with arbitrary (compact or non-compact) Gepner models for the K3 fiber, we construct modular invariant partition functions of general mirrorfold models. In the case of compact K3 fiber the mirrorfolds only yield non-supersymmetric string vacua. They exhibit IR instability due to winding tachyon condensation which is similar to the Scherk-Schwarz type circle compactification. When the fiber SCFT is non-compact (say, the ALE space in the simplest case), on the other hand, both supersymmetric and non-supersymmetric vacua can be constructed. The non-compact non-supersymmetric mirrorfolds can get stabilised at the level of string perturbation theory. We also find that in the non-compact supersymmeric mirrorfolds D-branes are always non-BPS. These D-branes can get stabilized against both open- and closed-string marginal deformations.

Stable and metastable vacua in brane constructions of SQCD

In a recent paper [1] we showed that N=1 supersymmetric QCD in the presence of certain superpotential deformations has a rich landscape of supersymmetric and non-supersymmetric vacua. In this paper we embed this theory in string theory as a low energy theory of intersecting NS and D-branes. We find that in the region of parameter space of brane configurations that can be reliably studied using classical string theory, the vacuum structure is qualitatively similar to that in the field theory regime. Effects that in field theory come from one loop corrections arise in string theory as classical gravitational effects. The brane construction provides a useful guide to the structure of stable and metastable gauge theory vacua.

Stable and metastable vacua in SQCD

We study deformations of N = 1 supersymmetric QCD that exhibit a rich landscape of supersymmetric and non-supersymmetric vacua.

Geometrically induced metastability and holography

We construct metastable configurations of branes and anti-branes wrapping 2-spheres inside local Calabi–Yau manifolds and study their large N duals. These duals are Calabi–Yau manifolds in which the wrapped 2-spheres have been replaced by 3-spheres with flux through them, and supersymmetry is spontaneously broken. The geometry of the non-supersymmetric vacuum is exactly calculable to all orders of the 't Hooft parameter, and to the leading order in 1 / N . The computation utilizes the same matrix model techniques that were used in the supersymmetric context. This provides a novel mechanism for breaking supersymmetry in the context of flux compactifications.

Metastable string vacua

We argue that tachyon-free type I string vacua with supersymmetry breaking in the open sector at the string scale can be interpreted, via S- and T-duality arguments, as metastable vacua of the supersymmetric type I superstring. The dynamics of the process can be partly captured via nucleation of brane–anti-brane pairs out of the non-supersymmetric vacuum and subsequent tachyon condensation.

Metastable vacua and D-branes at the conifold

We consider quiver gauge theories arising on D-branes at simple Calabi-Yau singularities (quotients of the conifold). These theories have metastable supersymmetry breaking vacua. The field theoretic mechanism is basically the one exhibited by the examples of Intriligator, Seiberg and Shih in SUSY QCD. In a dual description, the SUSY breaking is captured by the presence of anti-branes. In comparison to our earlier related work, the main improvements of the present construction are that we can reach the free magnetic range of the SUSY QCD theory where the existence of the metastable vacua is on firm footing, and we can see explicitly how the small masses for the quark flavors (necessary to the existence of the SUSY breaking vacua) are dynamically stabilized. One crucial mass term is generated by a stringy instanton. Finally, our models naturally incorporate R-symmetry breaking in the non-supersymmetric vacuum, in a way similar to the examples of Kitano, Ooguri and Ookouchi.

SUSY breaking by a metastable ground state: why the early Universe preferred the non-supersymmetric vacuum

Supersymmetry breaking in a metastable vacuum is re-examined in a cosmological context. It is shown that thermal effects generically drive the Universe to the metastable minimum even if it begins in the supersymmetry-preserving one. This is a generic feature of the ISS models of metastable supersymmetry breaking due to the fact that SUSY preserving vacua contain fewer light degrees of freedom than the metastable ground state at the origin. These models of metastable SUSY breaking are thus placed on an equal footing with the more usual dynamical SUSY breaking scenarios.

Why the early Universe preferred the non-supersymmetric vacuum: part II

It was recently shown in hep-th/0610334 that in the context of the ISS models with a metastable supersymmetry breaking vacuum, thermal effects generically drive the Universe to the metastable vacuum even if it began after inflation in the supersymmetry-preserving one. We continue this programme and specifically take into account two new effects. First is the effect of the mass-gap of the gauge degrees of freedom in the confining supersymmetry preserving vacua, and second, is the effect of the back reaction of the MSSM sector on the SUSY breaking ISS sector. It is shown that, even though the mass-gap is parametrically smaller than the <\phi> vevs, it drastically reduces the temperature required for the Universe to be driven to the metastable vacuum: essentially any temperature larger than the supersymmetry breaking scale \mu is sufficient. On the other hand we also find that any reasonable transmission of SUSY breaking to the MSSM sector has no effect on the vacuum transitions to, and the stability of the SUSY breaking vacuum. We conclude that for these models the early Universe does end up in the SUSY breaking vacuum.

Stable non-supersymmetric vacua in the moduli space of non-critical superstrings

We study a set of asymmetric deformations of non-critical superstring theories in various dimensions. The deformations arise as Kähler and complex structure deformations of an orthogonal two-torus comprising of a parallel and a transverse direction in the near-horizon geometry of NS5-branes. The resulting theories have the following intriguing features: Spacetime supersymmetry is broken in a continuous fashion and the masses of the lightest modes are lifted. In particular, no bulk or localized tachyons are generated in the non-supersymmetric vacua. We discuss the effects of these deformations in the context of the holographic duality between non-critical superstrings and little string theories and find solutions of rotating fivebranes in supergravity. We also comment on the generation of a one-loop cosmological constant and determine the effects of the one-loop backreaction to leading order.