We study the dynamics of a spherically symmetric thin shell of perfect fluid embedded in d-dimensional Anti-de Sitter space-time. In global coordinates, besides collapsing solutions, oscillating solutions are found where the shell bounces back and fo
rth between two radii. The parameter space where these oscillating solutions exist is scanned in arbitrary number of dimensions. As expected AdS3 appears to be singled out.
We study holographic models related to global quantum quenches in finite size systems. The holographic set up describes naturally a CFT, which we consider on a circle and a sphere. The enhanced symmetry of the conformal group on the circle motivates
us to compare the evolution in both cases. Depending on the initial conditions, the dual geometry exhibits oscillations that we holographically interpret as revivals of the initial field theory state. On the sphere, this only happens when the energy density created by the quench is small compared to the system size. However on the circle considerably larger energy densities are compatible with revivals. Two different timescales emerge in this latter case. A collapse time, when the system appears to have dephased, and the revival time, when after rephasing the initial state is partially recovered. The ratio of these two times depends upon the initial conditions in a similar way to what is observed in some experimental setups exhibiting collapse and revivals.
We review the construction of gravitational solutions holographically dual to N=1 quiver gauge theories with dynamical flavor multiplets. We focus on the D3-D7 construction and consider the finite temperature, finite quark chemical potential case whe
re there is a charged black hole in the dual solution. Discussed physical outputs of the model include its thermodynamics (with susceptibilities) and general hydrodynamic properties.
We analyze the charge diffusion and conductivity in a Dp/Dq holographic setup that is dual to a supersymmetric Yang-Mills theory in p+1 dimensions with N_f<< N_c flavour degrees of freedom at finite temperature and nonvanishing U(1) baryon number che
mical potential. We provide a new derivation of the results that generalize the membrane paradigm to the present context. We perform a numerical analysis in the particular case of the D3/D7 flavor system. The results obtained support the validity of the Einstein relation at finite chemical potential.
Using the AdS/CFT correspondence, we compute the spectral functions of thermal super Yang Mills at large N_c coupled to a small number of flavours of fundamental matter, N_f<<N_c, in the presence of a nonzero baryon density. The holographic dual of s
uch a theory involves the addition of probe D7-branes with a background worldvolume gauge field switched on, embedded in the geometry of a stack of black D3-branes. We perform the analysis in the vector and scalar channels which become coupled for nonzero values of the spatial momentum and baryon density. In addition, we obtain the effect of the presence of net baryon charge on the photon production. We also extract the conductivity and find perfect agreement with the results derived by Karch and OBannon in a macroscopic setup.
