We explore the efficacy of entanglement entropy as a tool for detecting thermal phase transitions in a family of gauge theories described holographically. The rich phase diagram of these theories encompasses first and second-order phase transitions, as well as a critical and a triple point. While entanglement measures demonstrate some success in probing transitions between plasma phases, they prove inadequate when applied to phase transitions leading to gapped phases. Nonetheless, entanglement measures excel in accurately determining the critical exponent associated with the observed phase transitions, providing valuable insight into the critical behavior of these systems.

We study the phase diagram of a strongly coupled confining theory in 2+1 dimensions, as a function of temperature and baryon chemical potential. The theory has a fully fledged supergravity holographic dual, that we use to predict a line of first-order phase transitions separating a confining phase and a deconfined phase. Both phases exhibit a nonzero baryon density thus providing a first example of baryonic matter in a confining string dual that does not require the introduction of flavor branes. We argue that the confining phase is a baryon superfluid, while the deconfined phase has nonzero baryon magnetization.

We study the phase diagram of a confining three-dimensional N = 1 super symmetric U(N) x U(N + M) theory with holographic dual corresponding to a known string theory solution. The theory possesses a global U(1) symmetry under which magnetic monopoles are charged. We introduce both temperature and an external magnetic field for monopoles and find that there are deconfinement phase transitions as any of the two is increased, supporting monopole condensation as the possible mechanism for confinement. We find that the transition as the magnetic field is increased is second order, providing the first example in holographic duals of a deconfinement transition which is not first order. We also uncover a rich structure in the phase diagram, with a triple point and a critical point where a line of first order transitions end.

The final mass distribution of primordial black holes is sensitive to the equation of state of the Universe at the scales accessible by the power spectrum. Motivated by the presence of phase transitions in several beyond the Standard Model theories, some of which are strongly coupled, we analyze the production of primordial black holes during such phase transitions, which we model using the gauge/gravity duality. We focus in the (often regarded as physically uninteresting) case for which the phase transition is just a smooth crossover. We find an enhancement of primordial black hole production in the range MPBH is an element of [10-16; 10-6]M circle dot.

We present some exact solutions to the ideal hydrodynamics of a relativistic superfluid with an almost-conformal equation of state. The solutions have stress tensors which are invariant under Lorentz boosts in one direction, and represent superfluid generalisations of the Bjorken and Gubser flows. We also study corrections to the flows in first-order hydrodynamics, arguing that dissipation is dominated by the shear viscosity. We present some simple numerical solutions for these viscous corrections. Finally, we estimate the size of corrections to the flows arising when the spontaneously broken U(1) symmetry responsible for superfluidity is only approximate, giving the corresponding Gold-stone boson a small non-zero mass. We find that the massless solutions can still provide good approximations at sufficiently small spatial rapidities.

The transport properties of dense QCD matter play a crucial role in the physics of neutron stars and their mergers but are notoriously difficult to study with traditional quantum field theory tools. Specializing to the case of unpaired quark matter in beta equilibrium, we approach the problem through the machinery of holography, in particular the V-QCD and D3-D7 models, and derive results for the electrical and thermal conductivities and the shear and bulk viscosities. In addition we compare the bulk to shear viscosity ratio to the speed of sound and find that it violates the so-called Buchel bound. Our results differ dramatically from earlier predictions of perturbative QCD, the root causes and implications of which we analyze in detail.