17 research outputs found
Supersymmetric sound in fluids
We consider the hydrodynamics of supersymmetric fluids. Supersymmetry is
broken spontaneously and the low energy spectrum includes a fermionic massless
mode, the . We use two complementary approaches to describe
the system: First, we construct a generating functional from which we derive
the equations of motion of the fluid and of the phonino propagating through the
fluid. We write the form of the leading corrections in the derivative
expansion, and show that the so called diffusion terms in the supercurrent are
in fact not dissipative. Second, we use an effective field theory approach
which utilizes a non-linear realization of supersymmetry to analyze the
interactions between phoninos and phonons, and demonstrate the conservation of
entropy in ideal fluids. We comment on possible phenomenological consequences
for gravitino physics in the early universe.Comment: Modified introduction and discussion of diffusion terms in the
supercurren
Diffusion constant of supercharge density in N=4 SYM at finite chemical potential
We compute holographically the diffusion constant of supercharges in N=4 SYM
at finite chemical potential for the R-charge, by solving the equations of
motion for the transverse mode of the gravitino in the STU black hole in 5
dimensions. We consider the case of one charge and three charges, and we
present analytical solutions for small values of the charges and numerical
solutions for arbitrary values. We compare our results with other known results
in 4 dimensions.Comment: 20 pages, 4 figures; v2: typos correcte
Entanglement of heavy quark impurities and generalized gravitational entropy
We calculate the contribution from non-conformal heavy quark sources to the entanglement entropy (EE) of a spherical region in N=4 SUSY Yang-Mills theory. We apply the generalized gravitational entropy method to non-conformal probe D-brane embeddings in AdS_5ĂS^5, dual to pointlike impurities exhibiting flows between quarks in large-rank tensor representations and the fundamental representation. For the D5-brane embedding which describes the screening of fundamental quarks in the UV to the antisymmetric tensor representation in the IR, the EE excess decreases non-monotonically towards its IR asymptotic value, tracking the qualitative behaviour of the one-point function of static fields sourced by the impurity. We also examine two classes of D3-brane embeddings, one which connects a symmetric representation source in the UV to fundamental quarks in the IR, and a second category which yields the symmetric representation source on the Coulomb branch. The EE excess for the former increases from the UV to the IR, whilst decreasing and becoming negative for the latter. In all cases, the probe free energy on hyperbolic space with ÎČ = 2Ï increases monotonically towards the IR, supporting its interpretation as a relative entropy. We identify universal corrections, depending logarithmically on the VEV, for the symmetric representation on the Coulomb branch
Confinement, phase transitions and non-locality in the entanglement entropy
In this paper we study the conjectural relation between confinement in a
quantum field theory and the presence of a phase transition in its
corresponding entanglement entropy. We determine the sufficient conditions for
the latter and compare to the conditions for having a confining Wilson line. We
demonstrate the relation in several examples. Superficially, it may seem that
certain confining field theories with a non-local high energy behaviour, like
the dual of D5 branes wrapping a two-cycle, do not admit the corresponding
phase transition. However, upon closer inspection we find that, through the
introduction of a regulating UV-cutoff, new eight-surface configurations
appear, that satisfy the correct concavity condition and recover the phase
transition in the entanglement entropy. We show that a local-UV-completion to
the confining non-local theories has a similar effect to that of the
aforementioned cutoff.Comment: 64 pages. Lots of figure