Wess-Zumino Consistency Condition for Entanglement Entropy

In this brief note, we consider the variation of the entanglement entropy of a region as the shape of the entangling surface is changed. We show that the variation satisfies a Wess-Zumino like integrability condition in field theories which can be consistently coupled to gravity. In this case the "anomaly" is localized on the entangling surface. The solution of the integrability condition should give all the nontrivial finite local terms which can appear in the variation of the entanglement entropy.Comment: 14 pages, presentation improve

Interpolating Action for Strings and Membranes - a Study of Symmetries in the Constrained Hamiltonian Approach

A master action for bosonic strings and membranes, interpolating between the Nambu--Goto and Polyakov formalisms, is discussed. The role of the gauge symmetries vis-\`{a}-vis reparametrization symmetries of the various actions is analyzed by a constrained Hamiltonian approach. This analysis reveals the difference between strings and higher branes, which is essentially tied to a degree of freedom count. The cosmological term for membranes follows naturally in this scheme. The conncetion of our aproach with the Arnowitt--Deser--Misner representation in general relativity is illuminated.Comment: LaTex, 23 pages; discussion on ADM representation included and new references adde

Semiclassical Strings in Supergravity PFT

Puff Field Theory (PFT) is an example of a non-local field theory which arises from a novel embedding of D-branes in Melvin universe. We study several rotating and pulsating string solutions of the F-string equations of motion in the supergravity dual of the PFT. Further, we find a PP-wave geometry from this nonlocal spacetime by applying a Penrose limit and comment on its similarity with the maximally supersymmetric PP-wave background.Comment: 21 pages, added clarification

A note on oscillating strings in AdS3×S3AdS_3 \times S^3 with mixed three-form fluxes

We present a detailed study of the pulsating string solutions in AdS3 x S3 supported by both RR and NS-NS fluxes. This background has recently been proved to be integrable. We find the dispersion relation between the energy, oscillation number and other conserved charges when the NS-NS flux turned on is small. We further discuss the fate of the string solutions in pure RR and NS-NS cases.Comment: 26 pages, version to appear in JHE

On multi-spin classical strings with NS-NS flux

We study multi spin semiclassical strings in $AdS_3\times S^3 \times T^4$ background supported by a mixture of Neveu-Schwarz-Neveu-Schwarz (NS-NS) and Ramond-Ramond (R-R) fluxes. This `mixed flux' background has been recently proved to be classically integrable. We start with a particular rigidly spinning fundamental string in $AdS_3\times S^1$ coupled to the NS-NS flux and classify the possible profiles. We also find out how the scaling relation among the energy and angular momenta of such a string changes due to presence of these fluxes. We emphasize on pure NS-NS flux case and discuss the fate of such solutions in that limit.Comment: 22 pages, 4 figure

Adiabatic charge pumping through a dot at the junction of N quantum wires

We study adiabatic charge pumping through a quantum dot placed at the junction of $N$ quantum wires. We explicitly map out the pattern of pumped charge as a function of the time-varying tunneling parameters coupling the wires to the dot and the phase between any two time varying parameters controlling the shape of the dot. We find that with $N-2$ time-independent well-coupled leads, the maximum pumped charge in the remaining two leads is strongly suppressed with increasing $N$, leading to the possibility of tuning of the pumped charge, by modulating the coupling of the $N-2$ leads.Comment: 5 pages, 6 figures, version to be published in PR

Spiky strings on AdS3 x S3 with NS-NS flux

We study rigidly rotating strings in the background of AdS3 x S3 with Neveu-Schwarz (NS) fluxes. We find two interesting limiting cases corresponding to the known giant magnon and the new single spike solution of strings in the above background and write down the dispersion relations among various conserved charges. We use proper regularization to find the correct relations among them. We further study the circular and infinite spiky strings on AdS and study their properties.Comment: 19 pages, added clarification, typos fixe