Soft branes in supersymmetry-breaking backgrounds (original) (raw)
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Softbranes in supersymmetri-breaking backgrounds
We revisit the analysis of effective field theories resulting from non-supersymmetric perturbations to supersymmetric flux compactifications of the type-IIB superstring with an eye towards those resulting from the backreaction of a small number of D3-branes. Independently of the background, we show that the low-energy Lagrangian describing the fluctuations of a stack of probe D3-branes exhibits soft supersymmetry breaking, despite perturbations to marginal operators that were not fully considered in some previous treatments. We take this as an indication that the breaking of supersymmetry by D3-branes or other sources may be spontaneous rather than explicit. In support of this, we consider the action of an D3-brane probing an otherwise supersymmetric configuration and identify a candidate for the corresponding goldstino.
Low-energy supersymmetry breaking from string flux compactifications: Benchmark scenarios
Journal of High Energy Physics, 2006
Soft supersymmetry breaking terms were recently derived for type IIB string flux compactifications with all moduli stabilised. Depending on the choice of the discrete input parameters of the compactification such as fluxes and ranks of hidden gauge groups, the string scale was found to have any value between the TeV and GUT scales. We study the phenomenological implications of these compactifications at low energy. Three realistic scenarios can be identified depending on whether the Standard Model lies on D3 or D7 branes and on the value of the string scale. For the MSSM on D7 branes and the string scale between 10 12 GeV and 10 17 GeV we find that the LSP is a neutralino, while for lower scales it is the stop. At the GUT scale the results of the fluxed MSSM are reproduced, but now with all moduli stabilised. For the MSSM on D3 branes we identify two realistic scenarios. The first one corresponds to an intermediate string scale version of split supersymmetry. The second is a stringy mSUGRA scenario. This requires tuning of the flux parameters to obtain the GUT scale. Phenomenological constraints from dark matter, (g − 2) µ and BR(b → sγ) are considered for the three scenarios. We provide benchmark points with the MSSM spectrum, making the models suitable for a detailed phenomenological analysis.
We show how to construct chiral tachyon-free perturbative orientifold models, where supersymmetry is broken at the string scale on a collection of branes while, to lowest order, the bulk and the other branes are supersymmetric. In higher orders, supersymmetry breaking is mediated to the remaining sectors, but is suppressed by the size of the transverse space or by the distance from the brane where supersymmetry breaking primarily occurred. This setting is of interest for orbifold models with discrete torsion, and is of direct relevance for low-scale string models. It can guarantee the stability of the gauge hierarchy against gravitational radiative corrections, allowing an almost exact supergravity a millimeter away from a non-supersymmetric world.
Accidental SUSY: enhanced bulk supersymmetry from brane back-reaction
We compute how bulk loops renormalize both bulk and brane effective interactions for codimension-two branes in 6D gauged chiral supergravity, as functions of the brane tension and brane-localized flux. We do so by explicitly integrating out hyper-and gauge-multiplets in 6D gauged chiral supergravity compactified to 4D on a flux-stabilized 2D rugby-ball geometry, specializing the results of a companion paper, arXiv:1210.3753, to the supersymmetric case. While the brane back-reaction generically breaks supersymmetry, we show that the bulk supersymmetry can be preserved if the amount of branelocalized flux is related in a specific BPS-like way to the brane tension, and verify that the loop corrections to the brane curvature vanish in this special case. In these systems it is the brane-bulk couplings that fix the size of the extra dimensions, and we show that in some circumstances the bulk geometry dynamically adjusts to ensure the supersymmetric BPS-like condition is automatically satisfied. We investigate the robustness of this residual supersymmetry to loops of non-supersymmetric matter on the branes, and show that supersymmetry-breaking effects can enter only through effective brane-bulk interactions involving at least two derivatives. We comment on the relevance of this calculation to proposed applications of codimension-two 6D models to solutions of the hierarchy and cosmological constant problems.
Brane-induced supersymmetry breaking
Journal of High Energy Physics, 2002
We study spontaneous supersymmetry breaking induced by brane-localized dynamics in five-dimensional supergravity compactified on S^1/Z_2. We consider a model with gravity in the bulk and matter localized on tensionless branes at the orbifold fixed points. We assume that the brane dynamics give rise to effective brane superpotentials that trigger the supersymmetry breaking. We analyze in detail the super-Higgs effect. We compute the full spectrum and show that the symmetry breaking is spontaneous but nonlocal in the fifth dimension. We demonstrate that the model can be interpreted as a new, non-trivial implementation of a coordinate-dependent Scherk-Schwarz compactification.
D-branes, supersymmetry breaking, and neutrinos
2010
This thesis studies meta-and exactly stable supersymmetry breaking mechanisms in heterotic and type IIB string theories and constructs an F-theory Grand Unified Theory model for neutrino physics in which neutrino mass is determined by the supersymmetry breaking mechanism.
MAD-TH-04-6 Model Building and Phenomenology of Flux-Induced Supersymmetry Breaking on D3-branes
2004
We study supersymmetry breaking effects induced on D3-branes at singularities by the presence of NSNS and RR 3-form fluxes. First, we discuss some local constructions of chiral models from D3-branes at singularities, as well as their global embedding in flux compactifications. The low energy spectrum of these constructions contains features of the supersymmetric Standard Model. In these models, both the soft SUSY parameters and the µ-term are generated by turning on the 3-form NSNS and RR fluxes. We then explore some model-independent phenomenological features as, e.g., the fine-tuning problem of electroweak symmetry breaking in flux compactifications. We also comment on other phenomenological
Model building and phenomenology of flux-induced supersymmetry breaking on D3-branes
Nuclear Physics B, 2005
We study supersymmetry breaking effects induced on D3-branes at singularities by the presence of NSNS and RR 3-form fluxes. First, we discuss some local constructions of chiral models from D3-branes at singularities, as well as their global embedding in flux compactifications. The low energy spectrum of these constructions contains features of the supersymmetric Standard Model. In these models, both the soft SUSY parameters and the µ-term are generated by turning on the 3-form NSNS and RR fluxes. We then explore some model-independent phenomenological features as, e.g., the fine-tuning problem of electroweak symmetry breaking in flux compactifications. We also comment on other phenomenological features of this scenario.
Journal of High Energy Physics, 2020
We discuss how to incorporate non-supersymmetric branes in compactifications of type II string theories. We particularly focus on flux compactifications on SU(3) × SU(3) structure manifolds to four dimensions, so that a linear mathcalN\mathcal{N}mathcalN N = 1 supersymmetry is spontaneously broken by spacetime filling Dp-branes. Anti-Dp-branes are a very special subset of such branes but our analysis is generic. We show that the backreaction of non-supersymmetric branes can be incorporated into the standard 4d mathcalN\mathcal{N}mathcalN N = 1 supergravity by including a nilpotent chiral multiplet. Supersymmetry in such setups is always spontaneously broken and non-linearly realized. In particular this means that, contrary to what was previously thought, brane supersymmetry breaking cannot be simply described by a D-term in 4d mathcalN\mathcal{N}mathcalN N = 1 supergravity theories.
Soft supersymmetry-breaking terms from supergravity and superstring models
1997
We review the origin of soft supersymmetry-breaking terms in N = 1 supergravity models of particle physics. We first consider general formulae for those terms in general models with a hidden sector breaking supersymmetry at an intermediate energy scale. The results for some simple models are given. We then consider the results obtained in some simple superstring models in which particular assumptions about the origin of supersymmetry breaking are made. These are models in which the seed of supersymmetry breaking is assumed to be originated in the dilaton/moduli sector of the theory.