Holographic phase transitions at finite baryon density

Abstract

We use holographic techniques to study SU (N c ) super Yang-Mills theory coupled to N f ≪ N c flavours of fundamental matter at finite temperature and baryon density. We focus on four dimensions, for which the dual description consists of N f D7-branes in the background of N c black D3-branes, but our results apply in other dimensions as well. A non-zero chemical potential µ b or baryon number density n b is introduced via a nonvanishing worldvolume gauge field on the D7-branes. Ref.[1] identified a first order phase transition at zero density associated with 'melting' of the mesons. This extends to a line of phase transitions for small n b , which terminates at a critical point at finite n b . Investigation of the D7-branes' thermodynamics reveals that (∂µ b /∂n b ) T < 0 in a small region of the phase diagram, indicating an instability. We comment on a possible new phase which may appear in this region.

Mesons in gauge/gravity duals

“…As an example we consider here spectral functions at finite temperature and the quark chemical potential as discussed in [209]. The phase diagram was found in [202,205] and is displayed in fig. 29.…”

“…30. The finite-temperature part of the spectral function R − R0 (in units of N f N T 2 /4) in the temperature-dominated region (upper plot) and in the potential-dominated region (lower plot).d parametrizes the quark density and χ0, introduced in [202], essentially corresponds to mq/T . Figures from [209].…”

Holographic quark gluon plasma with flavor

“…This section summarizes the results of the work of Myers et al on this topic [41,42,52,56] and provides a few additional remarks. This will help us to interpret our own results within this and similar setups that follow in the next sections and chapters.…”

“…In this context we will review the thermodynamics at finite U(1) baryon density [42] or finite baryon chemical potential [52] in section 4.3. Investigating the effects of isospin and the non-Abelian part of the flavor group we will develop the thermodynamics for the non-Abelian part SU(N f ) of the full flavor gauge symmetry U(N f ).…”

“…quarks and their bound states, the mesons [36] further studied in [37,38,39,40,41,42]. In particular in [37] it was found that a gravity black hole background induces a phase transition in the dual gauge theory.…”