125776289
tau ---> mu mu anti-mu and tau ---> mu e- e+ decays in string models with E-6 symmetry
44568977
Is the Gepner three generation model phenomenologically viable?
The low-energy spectrum of the Gepner three generation model constructed from the discrete series of the [ital N]=2 superconformal theory below the intermediate scale is studied. It is found that, aside from the usual standard model leptons and quarks, there appear four Higgs doublets, six exotic light neutral particles, and a pair of light color Higgs triplets. Although the proton is stable, the presence of these new particles and the difficulty for the up and down quarks and the first two lepton generations to grow nonzero masses may rule out this model phenomenologically. Despite this discouraging result we do find that the nonrenormalizable interactions can provide a viable mechanism to solve the lepton-quark mass hierarchy problem, due to the large VEV growth of the standard model singlet fields at the intermediate symmetry-breaking scale.
16298898
Landau pole effects and the parameter space of the minimal supergravity model.
It is shown that analyses at the electroweak scale can be significantly affected due to Landau pole effects in certain regions of the parameter space. This phenomenon arises due to a large magnification of errors of the input parameters $m_t$, $\alpha_G$ which have currently a 10 percent uncertainty in their determination. The influence of the Landau pole on the constraint that the scalar SUSY spectrum be free of tachyons is also investigated.It is found that this constraint is very strong and eliminates a large portion of the parameter space.Under the above constraint the trilinear soft SUSY breaking term at the electroweak scale is found to lie in a restricted domain.
38924798
Constraints on the minimal supergravity model from the b-->s gamma decay.
The constraints on the minimal supergravity model from the b → s decay are studied. A large domain in the parameter space for the model satisfies the CLEO bound, BR(b → s) 0, however, the branching ratio � � ,
118728823
Phenomenological Implications of Three-Generation Heterotic String Models.
106116857
Study of K- p ---> Lambda pi+ pi-, Lambda pi0 and gamma N ---> K+ Sigma*
119210702
Multi-Spin Strings in AdS_4*CP^3 and its \beta-deformations
In this paper, we study the multi-spin string solutions in AdS_4*CP^3 and its \beta-deformation with real \beta. We give various explicit solutions after some general studies. Conserved charges are computed for these explicit solutions.
41259393
Electrostatic and magnetostatic solutions in a Lorentz-violating electrodynamics model
We propose an effective Lorentz-violating electrodynamics model via the static de Sitter metric, which is deviated from the Minkowski metric by a minuscule amount depending on the cosmological constant. We obtain the electromagnetic field equations via the vierbein decomposition of the tensors. In addition, as an application of the electromagnetic field equations obtained, we derive the solutions of the electrostatic field and the magnetostatic field due to a point charge and a circle current, respectively, and discuss the implication of the effect of Lorentz violation in our electromagnetic theory.
6976924
(Non)-supersymmetric Marginal Deformations from Twistor String Theory
The tree-level amplitudes in the β-deformed supersymmetric gauge theory are derived from twistor string theory. We first show that a simple generalization of [M. Kulaxizi, K. Zoubos, Marginal deformations of N=4 SYM from open/closed twistor strings, Nucl. Phys. B 738 (2006) 317, hep-th/0410122] gives us the desired results for all the tree-level amplitudes up to first order in the deformation parameter β. Then we provide a new proposal which matches field theory to all orders of β. With our deformed twistor string theory, it can be shown that integration over connected instantons and disconnected instantons remain equivalent. The tree-level amplitudes in the non-supersymmetric γ-deformed theory can be obtained using a similar deformation of the twistor string. Finally, we find improved twistor string results for the tree-level purely gluonic amplitudes in theories with more general marginal deformations.
119208151
Holographic superconductors from the massive gravity
A holographic superconductor is constructed in the background of a massive gravity theory. In the normal state without condensation, the conductivity exhibits a Drude peak that approaches a delta function in the massless gravity limit as studied by David Vegh. In the superconducting state, besides the infinite DC conductivity, the AC conductivity has Drude behavior at low frequency followed by a power law-fall. These results are in agreement with that found earlier by Horowitz and Santos, who studied a holographic superconductor with an implicit periodic potential beyond the probe limit. The results also agree with measurements on some cuprates.