In arXiv:1403.0389 and arXiv:1610.07140 intersecting $D$-branes in flat space were studied at finite temperature in the Yang-Mills approximation. The one-loop correction to the tachyon mass was computed and the critical temperature at which the tachyon becomes massless was obtained numerically. In this paper we extend the computation of one-loop two-point amplitude to the case of intersecting stacks of $D3$-branes in flat space. The motivation for this calculation is to study the strong coupling holographic BCS model proposed in arXiv:1104.2843 at finite temperature. We show that the analytical results of arXiv:1403.0389 and arXiv:1610.07140 can be embedded into this more general setup. The main technicality involved here is keeping track of the extra color factors coming from the unbroken gauge groups. We further discuss the issues involved in the computation of two point amplitude for case of multiple intersecting stacks of branes.
We analyze proton decay via dimension six operators in certain GUT-like models derived from Type IIA orientifolds with $D6$-branes. The amplitude is parametrically enhanced by a factor of $alpha_{GUT}^{-1/3}$ relative to the coresponding result in four-dimensional GUTs. Nonetheless, even assuming a plausible enhancement from the threshold corrections, we find little overall enhancement of the proton decay rate from dimension six operators, so that the predicted lifetime from this mechanism remains close to $10^{36}$ years.
In this paper we study dynamical supersymmetry breaking in absence of gravity with the matter content of the minimal supersymmetric standard model. The hidden sector of the theory is a strongly coupled gauge theory, realized in terms of microscopic variables which condensate to form mesons. The supersymmetry breaking scalar potential combines F, D terms with instanton generated interactions in the Higgs-mesons sector. We show that for a large region in parameter space the vacuum breaks in addition to supersymmetry also electroweak gauge symmetry. We furthermore present local D-brane configurations that realize these supersymmetry breaking patterns.
We show that contrary to first expectations realistic three generation supersymmetric intersecting brane world models give rise to phenomenologically interesting predictions about gauge coupling unification. Assuming the most economical way of realizing the matter content of the MSSM via intersecting branes we obtain a model independent relation among the three gauge coupling constants at the string scale. In order to correctly reproduce the experimentally known values of sin^2[theta_W(M_z)] and alpha_s(M_z) this relation leads to natural gauge coupling unification at a string scale close to the standard GUT scale 2 x 10^16 GeV. Additional vector-like matter can push the unification scale up to the Planck scale.
For background gauge field configurations reducible to the form Amu = (A3, A(x)) where A3 is a constant, we provide an elementary derivation of the recently obtained result for the exact induced Chern-Simons (CS) effective action in QED3 at finite temperature. The method allows us to extend the result in several useful ways: to obtain the analogous result for the `mixed CS term in the Dorey-Mavromatos model of parity-conserving planar superconductivity, thereby justifying their argument for flux quantization in the model; to the induced CS term for a tau-dependent flux; and to the term of second order in A(x) (and all orders in A3) in the effective action.
String instanton effects in Higgs physics are discussed through a type IIA model based on T^{6}/(Z^{2}times Z^{2}) orentifold compactifaction. By inclusion of rigid E2-branes, the model exhibits a MSSM-like spectrum, as well as extra mu and quartic Higgs couplings. These extra couplings are induced via E2 instantons non-perturbatively. Setting the string scale at 10^{18} GeV, one gets interesting TeV Higgs physics. In particlular, the tree-level Higgs mass can be uplifted substantially.