Abstract
The ability to describe strongly interacting matter at finite temperature and baryon density provides the means to determine, for instance, the equation of state of QCD at non-zero baryon chemical potential. From a theoretical point of view, direct lattice simulations are hindered by the numerical sign problem, which prevents the use of traditional methods based on importance sampling. Despite recent successes, simulations using the complex Langevin method have been shown to exhibit instabilities, which cause convergence to wrong results. We introduce and discuss the method of dynamic stabilisation (DS), a modification of the complex Langevin process aimed at solving these instabilities. We present results of DS being applied to the heavy-dense approximation of QCD, as well as QCD with staggered fermions at zero chemical potential and finite chemical potential at high temperature. Our findings show that DS can successfully deal with the aforementioned instabilities, opening the way for further progress.
Highlights
Heavy-ion collisions have been successfully used to investigate the high temperature behaviour of QCD at the relativistic heavy ion collider (RHIC) and the large hadron collider (LHC)
Lattice QCD simulations at finite baryon/quark density are carried out using the grand canonical ensemble, with the chemical potential introduced as conjugate variable to the appropriate number density
We found that even with a large number of gauge cooling steps, instabilities still may appear [46] in simulations of heavy-dense limit of QCD (HDQCD), which we briefly review in Appendix A
Summary
Heavy-ion collisions have been successfully used to investigate the high temperature behaviour of QCD at the relativistic heavy ion collider (RHIC) and the large hadron collider (LHC) These facilities, together with future ones, namely the Facility for Antiproton and Ion Research (FAIR) and the nuclotron-based ion collider facility (NICA), will further explore the phase diagram of QCD. At finite quark chemical potential, the simulations have to overcome the infamous sign problem—a complex weight in the Euclidean path integral. This imposes severe limitations on the applicability of standard numerical methods [3,4]. Further discussions on the criteria for correct convergence of com-
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
