Hristo Dimov

Generalized pulsating strings

In this paper we consider new solutions for pulsating strings. For this purpose we use the idea of the generalized ansatz for folded and circular strings in [1]. We find the solutions to the resulting Neumann-Rosochatius integralbe system and the corrections to the energy. To do that we use the approach developed by Minahan in [2] and find that the corrections are quite different from those obtained in that paper and in [3]. We conclude with comments on our solutions and the obtained corrections to the energy, expanded to the leading order in lambda.

Semiclassical strings, dipole deformations of Script N = 1 SYM and decoupling of KK modes

In this paper we investigate the recently found °-deformed Maldacena-Nunez background by studying the behavior of different semiclassical string configurations. This background is conjectured to be dual to dipole deformations of N = 1 SYM. We compare our results to those in the pure Maldacena-Nunez background and show that the energies of our string configurations are higher than in the undeformed background. Thinking in the lines of (1) we argue that this is an evidence for better decoupling of the Kaluza-Klein modes from the pure SYM theory excitations. Moreover we are able to find a limit of the background in which the string energy is independent of °, these strings are interpreted as corresponding to pure gauge theory effects.

On the pulsating strings in AdS5 × T1, 1

We study the class of pulsating strings in AdS5 × T1, 1. Using a generalized ansatz for pulsating string configurations, we find new solutions of this class. Further we semiclassically quantize the theory and obtain the first correction to the energy. The latter, due to AdS/CFT correspondence, is supposed to give the anomalous dimensions of operators in the dual superconformal gauge field theory.

On the Pulsating Strings in Sasaki‐Einstein Spaces

We study the class of pulsating strings in AdS5×Yp,q and AdS5×Lp,q,r. Using a generalized ansatz for pulsating string configurations, we find new solutions for this class in terms of Heun functions, and derive the particular case of AdS5×T1,1, which was analyzed in arXiv:1006.1539 [hep‐th]. Unfortunately, Heun functions are still little studied, and we are not able to quantize the theory quasi‐classically and obtain the first corrections to the energy. The latter, due to AdS/CFT correspondence, is supposed to give the anomalous dimensions of operators of the gauge theory dual N = 1 superconformal field theory.

Non-abelian T-duality of Pilch-Warner background

In this work we obtain the non-abelian T-dual geometry of the well-known Pilch-Warner supergravity solution in its infrared point. We derive the dual metric and the NS two-form by gauging the isometry group of the initial theory and integrating out the introduced auxiliary gauge fields. Then we use the Fourier-Mukai transform from algebraic geometry to find the transformation rules of the R-R fields. The dual background preserves the supersymmetry of the original one due to the fact that the Killing spinor does not depend on the directions on which the N-AT-D is performed. Finally, we consider two different pp-wave limits of the T-dual geometry by performing Penrose limits for two light-like geodesics.

Strings on the deformed T 1,1 : giant magnon and single spike solutions

In this paper we have found giant magnon and single spike string solutions in a sector of the gamma-deformed conifold. We examined the dispersion relations and find a behavior analogous to the undeformed case. The transcendental functional relations between the conserved charges are shifted by a certain gamma-dependent term. The latter is proportional to the total momentum and thus qualitatively different from known cases.

Entanglement of higher-derivative oscillators in holographic systems

We study the quantum entanglement of coupled Pais–Uhlenbeck oscillators using the formalism of thermo-field dynamics. The entanglement entropy is computed for the specific cases of two and a ring of N coupled Pais–Uhlenbeck oscillators of fourth order. It is shown that the entanglement entropy depends on the temperatures, frequencies and coupling parameters of the different degrees of freedom corresponding to harmonic oscillators. We also make remarks on the appearance of instabilities of higher-derivative oscillators in the context of AdS/CFT correspondence. Finally, we advert to the information geometry theory by calculating the Fisher information metric for the considered system of coupled oscillators.

Large J expansion in ABJM theory revisited

Recently there has been progress in the computation of the anomalous dimensions of gauge theory operators at strong coupling by making use of the AdS/CFT correspondence. On the string theory side they are given by dispersion relations in the semiclassical regime. We revisit the problem of a large-charge expansion of the dispersion relations for simple semiclassical strings in an

Semiclassical Strings in Lunin-Maldacena Background

\mathrm{AdS}_4\times {\mathbb {CP}}^3