Pulsating strings from two dimensional CFT on (T4)N/S(N)(T^4)^N/S(N)

We propose a state from the two-dimensional conformal field theory on the orbifold $(T^4)^N/S(N)$ as a dual description for a pulsating string moving in $AdS_3$. We show that, up to first order in the deforming parameter, the energy in both descriptions has the same dependence on the mode number, but with a non-trivial function of the coupling.Comment: 10+4 pages. Misprints corrected. References added. Version published in Nuclear Physics

Strings from large charged fields

It has been known long time ago that the low energy dynamics of open-strings is described by non-abelian gauge theories in the same way that the low energy effective description of closed strings is governed by Einstein's gravity. In this short note, we review and comment on some examples where conversely, an effective behavior of non-abelian gauge theories in some particular limits are described by some type of extended objects like strings or branes. We constrain the discussion to a few examples sharing some similarities.Comment: 5 pages, 1 figure, Proceedings X SILAFAE Medellin-2014. To appear in Nuclear Physics B - Proceedings Supplement

Comments on Correlation Functions of Large Spin Operators and Null Polygonal Wilson Loops

We discuss the relation between correlation functions of twist-two large spin operators and expectation values of Wilson loops along light-like trajectories. After presenting some heuristic field theoretical arguments suggesting this relation, we compute the divergent part of the correlator in the limit of large 't Hooft coupling and large spins, using a semi-classical worldsheet which asymptotically looks like a GKP rotating string. We show this diverges as expected from the expectation value of a null Wilson loop, namely, as $(\ln{\mu^{-2}})^ 2$, $\mu$ being a cut-off of the theory.Comment: 16+3 pages, 3 figures. Computation in section 4.1 has been clarified. Some comments on the vertex contributions has been added in section 4.2. Some other minor corrections. Version to appear in Nucl. Phys.

Open strings on D-branes from ABJM

We study open strings on giant gravitons (D-branes on cycles) in the ABJM/$AdS_4\times \mathbb{CP}^3$ correspondence. We find that their energy spectrum has the same form as the one for closed strings, with a nontrivial function of the coupling, avoiding BMN scaling. A similar, Cuntz oscillator, Hamiltonian description for the string (operators at strong coupling) to the $AdS_5$ case is valid also in this case.Comment: 25 pages, 4 figures; paragraph removed at end of section 2, footnotes and references adde

Anomalous dimensions at finite conformal spin from OPE inversion

We compute anomalous dimensions of higher spin operators in Conformal Field Theory at arbitrary space-time dimension by using the OPE inversion formula of \cite{Caron-Huot:2017vep}, both from the position space representation as well as from the integral (viz. Mellin) representation of the conformal blocks. The Mellin space is advantageous over the position space not only in allowing to write expressions agnostic to the space-time dimension, but also in that it replaces tedious recursion relations in terms of simple sums which are easy to perform. We evaluate the contributions of scalar and spin exchanges in the $t-$channel exactly, in terms of higher order Hypergeometric functions. These relate to a particular exchange of conformal spin $\beta=\Delta+J$ in the $s-$channel through the inversion formula. Our exact results reproduce the special cases for large spin anomalous dimension and OPE coefficients obtained previously in the literature.Comment: 37 pages, not figures, some typos corrected, acknowledgement added. Added comments and clarifications regarding finite beta contribution