No Arabic abstract
This proceeding is based on arXiv:1105.0591 [hep-th] where we consider breaking of supersymmetry in intersecting D-brane configurations by slight deviation of the angles from their supersymmetric values. We compute the masses generated by radiative corrections for the adjoint scalars on the brane world-volumes. In the open string channel, the string two-point function receives contributions only from the infrared limits of N~4 and N~2 supersymmetric configurations, via messengers and their Kaluza-Klein excitations, and leads at leading order to tachyonic directions.
We construct the most general supersymmetric configuration of D2-branes and D6-branes on a 6-torus. It contains arbitrary numbers of branes at relative U(3) angles. The corresponding supergravity solutions are constructed and expressed in a remarkably simple form, using the complex geometry of the compact space. The spacetime supersymmetry of the configuration is verified explicitly, by solution of the Killing spinor equations. Our configurations can be interpreted as a 16-parameter family of regular extremal black holes in four dimensions. Their entropy is interpreted microscopically by counting the degeneracy of bound states of D-branes. Our result agrees in detail with the prediction for the degeneracy of BPS states in terms of the quartic invariant of the E(7,7) duality group.
In this paper we continue the study of the model proposed in the previous paper hep-th/0002077. The model consist of a system of extended objects of diverse dimensionalities, with or without boundaries, with actions of the Chern-Simons form for a supergroup. We also discuss possible connections with Superstring/M-theory.
We study the generic $p-p^prime$ system in the presence of constant NS 2-form $B_{ij}$ field. We derive properties concerning with the noncommutativity of D-brane worldvolume, the Green functions and the spectrum of this system. In the zero slope limit, a large number of light states appear as the lowest excitations in appropriate cases. We are able to relate the energies of the lowest states after the GSO projection with the configurations of branes at angles. Through analytic continuation, the system is compared with the branes with relative motion.
Extensions of the MSSM generically feature gauge singlet Higgs bosons. These singlet Higgs bosons have tan(beta)-enhanced Yukawa couplings to down-type quarks and leptons at the one-loop level. We present an effective Lagrangian incorporating these Yukawa couplings and use it to study their effect on singlet Higgs boson phenomenology within both the mnSSM and NMSSM. It is found that the loop-induced couplings represent an appreciable effect for the singlet pseudoscalar in particular, and may dominate its decay modes in some regions of parameter space.
Neutrino oscillation experiments are known to be sensitive to Non-Standard Interactions (NSIs). We extend the NSI formalism to include one-loop effects. We discuss universal effects induced by corrections to the tree level W exchange, as well as non-universal effects that can arise from scalar charged current interactions. We show how the parameters that can be extracted from the experiments are obtained from various loop amplitudes, which include vertex corrections, wave function renormalizations, mass corrections as well as box diagrams. As an illustrative example, we discuss NSIs at one loop in the Minimal Supersymmetric Standard Model (MSSM) with generic lepton flavor violating sources in the soft sector. We argue that the size of one-loop NSIs can be large enough to be probed in future neutrino oscillation experiments.