This is the 5th post in our series in which we have asked a number of leading scientists in our field to identify the 3-5 most important challenges which the field of hot and dense QCD matter theory has to address (click for the previous posts by Larry McLerran, Carsten Greiner, Nu Xu and Dmitri Kharzeev).
- What is the state of matter at temperatures between TC and 2 TC, and how it is related to the weakly interacting QGP at high enough temperature?
- What is the “direct” evidence of the QCD phase transition (or rapid crossover) and TC (or pseudo critical temperature) in relativistic heavy ion collisions?
- What is the exact location of the critical point(s) in the QCD phase diagram?
- What is the state of matter at baryon densities between
ρ0 and 10 ρ0 relevant to the interior of neutron stars?
To answer the above questions, the following immediate challenges need to be addressed:
- Determination of TC (or the pseudo critical temperature)
with a few % accuracy right at the physial u,d,s masses in lattice QCD. Dynamical fermions having good chiral properties must be used.
- Calculation of spectral functions of q-qbar and qqq states in all spin-flavor channels below and above TC in full QCD simulations.
Also we need to develop new theoretical approaches such as
- a non-equilibrium formulation of lattice field theory and its
- method(s) to simulate QCD at high baryon density.
- testing of theories of QCD at high baryon density in collaboration with cold atom experiments.