100 likes | 258 Views
Crossover, fluctuations and Anderson transition in quark matter formation. Boris Kerbikov,ITEP. The physics of (nuclear matter) (quark matter) transition. QCD phase diagram. We are here today. T. Triple point (Stephanov). T c. BCS (Son). Hadron gas. CFL. 2SC. (GeV). 0.3.
E N D
Crossover, fluctuations and Anderson transition in quark matter formation Boris Kerbikov,ITEP
The physics of (nuclear matter) (quark matter) transition QCD phase diagram We are here today T Triple point (Stephanov) Tc BCS (Son) Hadron gas CFL 2SC (GeV) 0.3 0.6
The interplay of three events • BEC-BCS crossover • Strong fluctuations • Anderson transition (?) Transition region: • ( 0.3 – 0.5 ) GeV n = - / (3-5 ) times > n of normal nuclear matter n1/3 1 fm-1
The key parameters describing the NM QM transition • n1/3 1 – the BCS-BEC crossover parameter, n is the quark number density, is the qq pair size (for BCS n1/3 103 ) • Gi 10-2 – the Ginzburg-Levanyuk number (Gi 10-12 – 10-14 for BCS ) • kFlmfp 1 fm – Anderson parameter ( l – mean free path ) The three parameters are interconnected
Crossover - what is it? gap Fluctuating pairs Cooper pairs Gas of tightly Bound pairs n1/3 g/g0
Crossover for Quarks In 2SC phase u- and d-quarks are paired, s- is out of the game Pairing pattern: scalar, color 3, flavor singlet Pairing mechanism: 4-fermion interaction ( NJL, or instantons, or gluon echange) ( 1 – 2 ) fm Quark matter emerges in the crossover regime rather than in BCS
NM QM transition goes with strong fluctuations Ginzburg – Levanyuk parameter is a measure of fluctuations • Tc ( 40 – 50 ) Mev • 400 Mev In BSC Gi 10-12 – 10-14, in HTSC Gi 10-5 Fluctuations and Crossover Gi 0.4 / ( n1/3 )4 Gi 10- 2
Color diamagnetism Fluctuations of the gluon field are more important than fluctuations of quark pairs Two effects: • Lowering of the critical temperature T* = Tc ( 1- g22< A2 > ) • First order phase transition instead of second – cubic term in Ginzburg-Landau functional
Anderson localization in quark matter Anderson localization – dynamical diffusion coefficient turns zero due to random impurities Ioffe-Regel criterion kFl 1, l is the quark mean free path Impurities – stochastic field configurations (e.g.,instantons) kF 400 Mev, l 1 fm, close to the mobility edge D = 0 Along with D the gradient term in GL functional is suppressed
CONCLUSIONS • The dynamics of NM QM transition is ill known • The phenomenology of NM QM transition includes three main events: 1) Crossover from strong coupling/low density to weak coupling/high density (BCS) 2) Strong fluctuations including color diamagnetism 3) Possible Anderson localization of quarks The three events are interconnected