Supersymmetry Breaking In Theories Research Articles

Non-minimal scalar multiplets, supersymmetry breaking and dualities

We study supersymmetry breaking in theories with non-minimal multiplets (such as the complex linear or CNM multiplets), by using superspace higher derivative terms which give rise to new supersymmetry breaking vacuum solutions on top of the standard supersymmetric vacuum. We illustrate the decoupling of the additional massive sectors inside the complex linear and the CNM multiplets and show that only the Goldstino sector is left in the low energy limit. We also discuss the duality between non-minimal scalar multiplets and chiral multiplets in the presence of superspace higher derivatives. From the superspace Noether procedure we calculate the supercurrents, and we show that in the supersymmetry breaking vacuum the chiral superfield X which enters the Ferrara-Zumino supercurrent conservation equation does indeed flow in the IR to the chiral constrained Goldstino superfield. We also provide a description of the Goldstino sector in terms of the Samuel-Wess superfield for the supersymmetry breaking mechanism at hand.

Dynamical supersymmetry breaking in theories without Lagrangians

We demonstrate that the supersymmetry is dynamically broken in the four-dimensional SU(N) gauge theory coupled to a strongly-coupled superconformal theory T_N. This is a direct generalization of the model of supersymmetry breaking on deformed moduli space in supersymmetric QCD with an SU(2) gauge group.

Hunting for dynamical supersymmetry breaking in theories that s-confine

The s-confining theories are a class of supersymmetric gauge theories with infrared dynamics which are well-understood. Perturbing such theories can give rise to dynamical supersymmetry breaking. We realize simple models of dynamical supersymmetry breaking by perturbing two of the 10 SU(N) s-confining gauge theories by a single trilinear operator. These examples have locally stable vacua with spontaneous supersymmetry breaking. The first is SU(5) with two generations (consisting of an antisymmetric tensor and an antifundamental) plus two flavors. The second is SU(5) with three generations. The properties of the former vacuum are calculable while those of the latter vacuum are not. We briefly discuss the other SU(N) models.

Regulating Eternal Inflation II: The Great Divide

In a previous paper, two of the authors presented a "regulated" picture of eternal inflation. This picture both suggested and drew support from a conjectured discontinuity in the amplitude for tunneling from positive to negative vacuum energy, as the positive vacuum energy was sent to zero; analytic and numerical arguments supporting this conjecture were given. Here we show that this conjecture is false, but in an interesting way. There are no cases where tunneling amplitudes are discontinuous at vanishing cosmological constant; rather, the space of potentials separates into two regions. In one region decay is strongly suppressed, and the proposed picture of eternal inflation remains viable; sending the (false) vacuum energy to zero in this region results in an absolutely stable asymptotically flat space. In the other region, we argue that the space-time at vanishing cosmological constant is unstable, but not asymptotically Minkowski. The consequences of our results for theories of supersymmetry breaking are unchanged.

Predictions of the sign ofμfrom supersymmetry breaking models

The sign of the supersymmetric Higgs boson mass \ensuremath{\mu} is usually taken as an independent input parameter in analyses of the supersymmetric standard model. I study the role of theories of supersymmetry breaking in determining the sign of \ensuremath{\mu} as an output. Models with vanishing soft scalar couplings at the apparent gauge coupling unification scale are known to predict a positive \ensuremath{\mu}. I investigate more general results for the sign of \ensuremath{\mu} as a function of the holomorphic soft scalar couplings, and compare to predictions of models with gaugino mass dominance at higher scales. In a significant region of the ${B}_{0}{/m}_{1/2}$ versus ${A}_{0}{/m}_{1/2}$ plane including ${A}_{0}{=B}_{0}=0, \ensuremath{\mu}$ must be positive. In another region, \ensuremath{\mu} is definitely negative. Only in a smaller intermediate region does knowledge of the supersymmetry breaking mechanism not permit a definite prediction of the sign of \ensuremath{\mu}. The last region will shrink considerably as the top quark mass becomes more accurately known.

Branes and vector-like supersymmetry breaking theories with gauged global symmetry

We show that the brane configuration describing the Izawa-Yanagida-Intriligator-Thomas (IYIT) model with gauged U(1) global symmetry subgroup contains inconsistent geometry, implying that there exists a stable vacuum where supersymmetry is dynamically broken.

Nucleosynthesis bounds in gauge-mediated supersymmetry breaking theories

In gauge-mediated supersymmetry breaking theories the next-to-lightest supersymmetric particle can decay during or after the nucleosynthesis epoch. The decay products such as photons and hadrons can destroy the light element abundances. Restricting the damage that these decays can do leads to constraints on the abundance and lifetime of the NLSP. We compute the freezeout abundance of the NLSP by including all coannihilation thresholds which are particularly important in the case in which the NLSP is the lightest stau. We find that the upper bound on the messenger scale can be as stringent as 10 12 GeV when the NLSP is the lightest neutralino and 10 13 GeV when the NLSP is the lightest stau. Our findings disfavour models of gauge mediation where the messenger scale is close to the GUT scale or results from balancing renormalisable interactions with non-renormalisable operators at the Planck scale. When combined with the requirement of no gravitino overabundance, our bound implies that the reheating temperature after inflation must be less than 10 7 GeV.

Cosmological moduli problem in gauge-mediated supersymmetry breaking theories

A generic class of string theories predicts the existence of light moduli fields, and they are expected to have masses $m_\phi$ comparable to the gravitino mass $m_{3/2}$ which is in a range of $10^{-2}$keV--1GeV in gauge-mediated supersymmetry breaking theories. Such light fields with weak interactions suppressed by the Planck scale can not avoid some stringent cosmological constraints, that is, they suffer from `cosmological moduli problems'. We show that all the gravitino mass region $10^{-2}$keV $\lesssim m_{3/2} \lesssim$ 1GeV is excluded by the constraints even if we incorporate a late-time mini-inflation (thermal inflation). However, a modification of the original thermal inflation model enables the region $10^{-2}$keV $\lesssim m_{3/2} \lesssim$ 500keV to survive the constraints. It is also stressed that the moduli can be dark matter in our universe for the mass region $10^{-2}$keV $\lesssim m_\phi \lesssim$ 100keV.

Dynamical supersymmetry breaking in models with a Green–Schwarz mechanism

We consider supersymmetry breaking in theories with gaugino condensation in the presence of an anomalous U(1) symmetry with anomaly cancellation by the Green-Schwarz mechanism. In these models, a Fayet-Iliopoulos D-term can give important contributions to the soft supersymmetry-breaking scalar masses. Most discussions of this possibility have ignored the dilaton field. We argue that this is not appropriate in general, and show that the F-term contributions to the soft breaking terms are comparable to or much larger than the D-term contributions, depending on how the dilaton is stabilized. We discuss phenomenological implications of these results.

Gauge-mediated supersymmetry breaking without fundamental singlets

The messenger sector of existing models of gauge-mediated supersymmetry breaking may be simplified by using a non-renormalizable superpotential term to couple the vector-like quark and lepton messenger fields to a chiral gauge-invariant of the supersymmetry-breaking sector. This eliminates the need for a fundamental singlet and for an additional gauge sector needed to generate appropriate expectation values for the singlet component fields. This scenario is more natural if the supersymmetry-breaking sector itself involves a non-renormalizable superpotential. Several examples are constructed based on non-renormalizable $SU(n)\times SU(n-1)$ supersymmetry-breaking theories.

Constraints fromb→sγon gauge-mediated supersymmetry-breaking models

We consider the branching ratio of $b \to s\gamma$ in gauge mediated supersymmetry breaking theories. Useful bounds on the parameter space of these models are derived from the experimental bounds on $b \to s\gamma$. Constraints on masses of NLSP are presented as a function of $tan\beta$ and $M/\Lambda$ for $\mu<0$ and $\mu>0$.

Constraint on cosmic density of the string moduli field in gauge-mediated supersymmetry-breaking theories

We derive a constraint on the cosmic density of string moduli fields in gauge-mediated supersymmetry-breaking theories by requiring that photons emitted from the unstable moduli fields should not exceed the observed X-ray backgrounds. Since mass of the moduli field lies in the range between $O(0.1)$keV and $O(1)$MeV and the decay occurs through a gravitational interaction, the lifetime of the moduli field is much longer than the age of the present universe. The obtained upperbound on their cosmic density becomes more stringent than that from the unclosure condition for the present universe for the mass greater than about 100keV.

Cosmological implications of dynamical supersymmetry breaking

We provide a taxonomy of dynamical supersymmetry-breaking theories, and discuss the cosmological implications of the various types of models. Models in which supersymmetry breaking is produced by chiral superfields which only have interactions of gravitational strength (e.g., string theory moduli) are inconsistent with standard big bang nucleosynthesis unless the gravitino mass is greater than \AA{}3 \ifmmode\times\else\texttimes\fi{} ${10}^{4}$ GeV. This problem cannot be solved by inflation. Models in which supersymmetry is dynamically broken by renormalizable interactions in flat space have no such cosmological problems. Supersymmetry can be broken either in a hidden or the visible sector. However, hidden sector models suffer from several naturalness problems and have difficulties in producing an acceptably large gluino mass.