We consider the quantum loop effects in scalar electrodynamics on de Sitter space by making use of the functional renormalization group approach. We first integrate out the photon field, which can be done exactly to leading (zeroth) order in the gradients of the scalar field, thereby making this method suitable for investigating the dynamics of the infrared sector of the theory. Assuming that the scalar remains light we then apply the functional renormalization group methods to the resulting effective scalar theory and focus on investigating the effective potential, which is the leading order contribution in the gradient expansion of the effective action. We find symmetry restoration at a critical renormalization scale $\kappa=\kappa_{\rm cr}$ much below the Hubble scale $H$. When compared with the results of Serreau and Guilleux [arXiv:1306.3846 [hep-th], arXiv:1506.06183 [hep-th]] we find that the photon facilitates symmetry restoration such that it occurs at an RG scale $\kappa_{\rm cr}$ that is higher than in the case of a pure scalar theory. The true effective potential is recovered when $\kappa\rightarrow 0$ and in that limit one obtains the results that agree with those of stochastic inflation, provided one interprets it in the sense as advocated by Lazzari and Prokopec [arXiv:1304.0404 [hep-th]].
The "long" indecomposable N=2, d=1 multiplet (2, 4, 2) defined in arXiv:1503.05537 [hep-th] as a deformation of the pair of chiral multiplets (2, 2, 0) and (0, 2, 2) by a number of the mass-dimension parameters is described in the superfield approach. We present its most general superfield and component actions, as well as a generalization to the case with the superfields of the opposite Grassmann parities and dimensionless deformation parameter. We show that the long N=2, d=1 multiplets are naturally embedded into the chiral SU(2|1), d=1 superfields having nonzero external spins with respect to SU(2) \subset SU(2|1). A superfield with spin s contains 2s long multiplets and two short multiplets (2, 2, 0) and (0, 2, 2). Two possible N=4, d=1 generalizations of the N=2 long multiplet in the superfield approach are also proposed.
In this paper, we try to prove the absence of the ghosts in case of the general nonlinear massive gravity action in Stuckelberg formalism. We argue that in order to find the explicit form of the Hamiltonian it is natural to start with the general nonlinear massive gravity action [S. F. Hassan and R. A. Rosen, Phys. Rev. Lett. 108, 041101 (2012), arXiv:1106.3344 [hep-th]]. We perform the complete Hamiltonian analysis of the Stuckelberg form of the minimal the nonlinear gravity action in this formulation and show that the constraint structure is so rich that it is possible to eliminate nonphysical modes. Then, we extend this analysis to the case of the general nonlinear massive gravity action. We find the corresponding Hamiltonian and collection of the primary constraints. Unfortunately we are not able to finish the complete analysis of the stability of all constraints due to the complex form of one primary constraint so that we are not able to determine the conditions under which given constraint is preserved during the time evolution of the system.
Recently a low-energy effective theory on non-Abelian semilocal vortices in SQCD with the U(N) gauge group and N + \tilde{N} quark flavors was obtained in field theory arXiv:1104.2077. The result is exact in a certain limit of large infrared cut-off. The resulting model was called the zn model. We study quantum dynamics of the zn model in some detail. First we solve it at large N in the leading order. Then we compare our results with those of Hanany and Tong hep-th/0403158 (the HT model) who based their derivation on a certain type-IIA formalism, rather than on a field-theory construction. In the 't Hooft limit of infinite N both model's predictions are identical. At finite N our calculations agree with the Hanany-Tong results only in the BPS sector. Beyond the BPS sector there is no agreement between the zn and HT models. Finally, we study perturbation theory of the zn model from various standpoints.
In arXiv:1101.3326[hep-th], a (2+1)-dimensional holographic Josephson junction was constructed, and it was shown that the DC Josephson current is proportional to the sine of the phase difference across the junction. In this paper, we extend this study to a holographic description for the (3+1)-dimensional holographic DC Josephson junction. By solving numerically the coupled differential equations, we also obtain the familiar characteristics of Josephson junctions.
We give a review on our recent work arXiv:1006.0779 [hep-th] and arXiv:1006.1719 [hep-th], in which properties of holographic strange metals were investigated. The background is chosen to be anisotropic scaling solution in Einstein-Maxwell-Dilaton theory with a Liouville potential. The effects of bulk Maxwell field, an extra U (1) gauge field and probe D-branes on the DC conductivity, the DC Hall conductivity and the AC conductivity are extensively analyzed. We classify behaviors of the conductivities according to the parameter ranges in the bulk theory and characterize conditions when the holographic results can reproduce experimental data.
Abstract Modified Gauss–Bonnet, i.e., f ( G ) gravity is a possible explanation of dark energy. Late time cosmology for the f ( G ) gravity non-minimally coupled with a free massless scalar field have been investigated in Ref. [S. Nojiri, S.D. Odintsov, P.V. Tretyakov, Phys. Lett. B 651 (2007) 224, arXiv:0704.2520 [hep-th] ; S. Nojiri, S.D. Odintsov, P.V. Tretyakov, Progr. Theor. Phys. Suppl. 172 (2008) 81, arXiv:0710.5232]. In this Letter we generalize the work of Ref. [S. Nojiri, S.D. Odintsov, P.V. Tretyakov, Phys. Lett. B 651 (2007) 224, arXiv:0704.2520 [hep-th] ; S. Nojiri, S.D. Odintsov, P.V. Tretyakov, Progr. Theor. Phys. Suppl. 172 (2008) 81, arXiv:0710.5232 ] by including scalar potential in the matter Lagrangian which is non-minimally coupled with modified Gauss–Bonnet gravity. Also we obtain the conditions for having a much more amazing problem than the acceleration of the universe, i.e. crossing of ω = − 1 , in f ( G ) non-minimally coupled with tachyonic Lagrangian.
Abstract We study metastable nonsupersymmetric configurations in type IIA string theory, obtained by suspending D4-branes and D 4 ¯ -branes between holomorphically curved NS5's, which are related to those of hep-th/0610249 by T-duality. When the numbers of branes and antibranes are the same, we are able to obtain an exact M theory lift which can be used to reliably describe the vacuum configuration as a curved NS5 with dissolved RR flux for g s ≪ 1 and as a curved M5 for g s ≫ 1 . When our weakly coupled description is reliable, it is related by T-duality to the deformed IIB geometry with flux of hep-th/0610249 with moduli exactly minimizing the potential derived therein using special geometry. Moreover, we can use a direct analysis of the action to argue that this agreement must also hold for the more general brane/antibrane configurations of hep-th/0610249 . On the other hand, when our strongly coupled description is reliable, the M5 wraps a nonholomorphic minimal area curve that can exhibit quite different properties, suggesting that the residual structure remaining after spontaneous breaking of supersymmetry at tree level can be further broken by the effects of string interactions. Finally, we discuss the boundary condition issues raised in hep-th/0608157 for nonsupersymmetric IIA configurations, their implications for our setup, and their realization on the type IIB side.
We investigate a string/M theoretic realization of the varying speed of light scenario. We consider a (3+1)-dimensional probe-brane universe in the background of a black hole in the bulk formed by a stack of branes, in the spirit of Kiritsis (hep-th/9906206). We generalize the dynamics of the system at hand by including rotation and Hubble damping of the bulk space-time and show that this may lead to a mechanism to stabilize the brane-universe and hence fix the speed of light at late times.
Abstract Using the covariant N =2 harmonic supergraph techniques we calculate the one-loop low-energy effective action of N =4 super-Yang–Mills theory in Coulomb branch with gauge group SU(2) spontaneously broken down to U(1). The full dependence of the low-energy effective action on both the hypermultiplet and gauge fields is determined. The direct quantum calculation confirms the correctness of the exact N =4 SYM low-energy effective action derived in hep-th/0111062 on the purely algebraic ground by invoking a hidden N =2 supersymmetry which completes the manifest N =2 one to N =4 . Our results provide an exhaustive solution to the problem of finding out the exact completely N =4 supersymmetric low-energy effective action for the theory under consideration.
Abstract Using superspace projection operators we provide a classification of (3/2,2) off-shell supermultiplets which are realized in terms of a real axial vector superfield, with or without compensating superfields. Any linearized supergravity action is shown to be a superposition of those corresponding to (i) old minimal supergravity, (ii) new minimal supergravity and (iii) the novel (3/2,2) off-shell supermultiplet with 12+12 degrees of freedom obtained in hep-th/0201096 .
Abstract A natural extension of the Dijkgraaf–Vafa proposal is to include fields in the fundamental representation of the gauge group. In this paper we use field theory techniques to analyze gauge theories whose tree level superpotential is a generic polynomial in multi-trace operators constructed out of such fields. We show that the effective superpotential is generated by planar diagrams with at most one (generalized) boundary. This justifies the proposal put forward in [I. Bena, R. Roiban, hep-th/0211075 ]. We then proceed to extend the gauge theory-matrix model duality to include baryonic operators. We obtain the full moduli space of vacua for an U ( N ) theory with N flavors. We also outline a program leading to a string theory justification of the gauge theory-matrix model correspondence with fundamental matter.