Holographic gravity in many dimensions predicts only small supercooling in confinement transitions
This paper studies how a class of strongly interacting particle theories cool and change phase by using a gravitational picture. In that picture, a four‑dimensional confining gauge theory is modelled by gravity in higher dimensions. The authors show that if one generalises the gravity side to D+1 spacetime dimensions and expands in 1/D (the inverse number of dimensions), a clear and simple prediction emerges: the deconfined phase cannot supercool by a large amount. Supercooling here means the deconfined phase persisting below the critical temperature; the authors quantify it as ε_sc = 1 − T_min/T_c, where T_min is the lowest temperature at which the deconfined (black‑brane) solution exists and T_c is the transition temperature.
What the authors did was to take Einstein gravity coupled to a scalar field (a common holographic model) and solve the equations in a 1/D expansion. In this setup the black‑brane geometry that represents the deconfined phase has its main effects confined to a thin layer near the horizon. The relevant length scale near the horizon is the local AdS (Anti‑de Sitter) curvature divided by D, so for large D the problem splits into a near‑horizon region and a far region that can be solved separately and then matched. This separation makes an analytic construction of the black‑brane solution possible at leading order in 1/D.
From that analysis the authors find two concrete results. First, the black‑brane solution ceases to exist below a minimal temperature T_min, so the amount of possible supercooling is finite. Second, the maximum supercooling is generically small for large D: it is suppressed by a factor of 1/D^2. At leading order they obtain the remarkably simple relation ε_sc = c_s^2(T_c)/2, where c_s is the speed of sound in the deconfined phase evaluated at the critical temperature. The paper reports that these predictions match explicit calculations in three examples they check: an exponential superpotential case, an improved holography model, and the thermal transition of N=4 super Yang–Mills theory on a sphere.