Gauge-invariant inflaton in the minimal supersymmetric standard model

We argue that all the necessary ingredients for successful inflation are present in the flat directions of the Minimally Supersymmetric Standard Model. We show that out of many gauge-invariant combinations of squarks, sleptons, and Higgs bosons, there are two directions, LLe and udd, which are promising candidates for the inflaton. The model predicts more than 10(3) e-foldings, with an inflationary scale of H(inf) approximately O(1-10) GeV, provides a tilted spectrum with an amplitude of delta(H) approximately 10(-5) and a negligible tensor perturbation. The temperature of the thermalized plasma could be as low as T(rh) approximately O(1-10) TeV. Parts of the inflaton potential can be determined independently of cosmology by future particle physics experiments.     

Charged current universality in the minimal supersymmetric standard model

We compute the complete one-loop contributions to low-energy charged current weak interaction observables in the minimal supersymmetric standard model (MSSM). We obtain the constraints on the MSSM parameter space which arise when precision low-energy charged current data are analyzed in tandem with measurements of the muon anomaly. While the data allow the presence of at least one light neutralino, they also imply a pattern of mass splittings among first and second generation sleptons and squarks which contradicts predictions of widely used models for supersymmetry-breaking mediation.     

Neutrino charge radius in the minimal supersymmetric standard model

As recently suggested by Degrassi, Marciano, and Sirlin, the electromagnetic form factor of the neutrino extracted from low energy elastic scattering cross sections ofv e and can be used to define the neutrino charge radius in the Standard Model in a gauge-invariant way. The complete one-loop contributions to the form factor consist not only the induced vertex but also the Z vertex corrections and theW andZ propagators arise from the counterterm diagrams, and theWW andZZ box diagrams. We show that the neutrino charge radius is a finite and gauge independent quantity in the Minimal Supersymmetric Standard Model. We consider only the oblique corrections to the neutrino charge radius in our numerical work, because the vertex and box contributions are small. The dependence of the oblique corrections on the supersymmetric parameters in each of the three sectors: Higgs, scalar matter and gaugino sectors are studied by taking into account of the current experimental bounds from LEP.     

A non-commutative version of the minimal supersymmetric standard model

A minimal supersymmetric standard model on non-commutative space-time (NC MSSM) is proposed. The model fulfills the requirements of non-commutative gauge invariance and the absence of anomaly. The existence of supersymmetry with a scale of its breaking lower than the non-commutative scale is crucial in order to achieve consistent gauge symmetry breaking.     

Mechanisms of supersymmetry breaking in the minimal supersymmetric standard model

We provide a bird’s eyeview of current ideas on supersymmetry breaking mechanisms in the MSSM. The essentials of gauge, gravity, anomaly and gaugino/higgsino mediation mechanisms are covered briefly and the phenomenology of the associated models is touched upon. A few statement are also made on braneworld supersymmetry breaking.     

Curvaton scenario within the minimal supersymmetric standard model and predictions for non-Gaussianity

We provide a model in which both the inflaton and the curvaton are obtained from within the minimal supersymmetric standard model, with known gauge and Yukawa interactions. Since now both the inflaton and curvaton fields are successfully embedded within the same sector, their decay products thermalize very quickly before the electroweak scale. This results in two important features of the model: first, there will be no residual isocurvature perturbations, and second, observable non-Gaussianities can be generated with the non-Gaussianity parameter f(NL)~O(5-1000) being determined solely by the combination of weak-scale physics and the standard model Yukawa interactions.