Nuclear Matter Physics Experiment Insights
Explore the experimental views on dense nuclear matter in the context of SIS100 at GSI, focusing on degrees of freedom, chiral symmetry restoration, and the phase diagram of nuclear matter. Discover critical aspects related to meson dominance, mass shifts, and the search for chiral symmetry restoration signatures in high-energy collisions.
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Nuclear Matter Physics at SIS100, GSI, April 2009 Dense Nuclear Matter: an experimentalists view Joachim Stroth, Goethe-University / GSI
What are the relevant degrees of freedom of nuclear matter at 2 - 5 0?
20 years of dileptons from HI collisions The search for signatures of a partial restoration of the spontaneously broken chiral symmtery (SB S): look for the meson (Vector Meson Dominance). Mass shifts ( condesate): G. E. Brown and M. Rho T. Hatsuda and S. H. Lee Broadening (hadronic): B. Friman, H.J. Pirner . F. Klingl, W. Weise . R. Rapp and J. Wambach As of today no rigorous evidence for restoration! No evidence for in-medium from HADES! See arXiv:0901.3289v1 (Hees, Rapp, Wambach) for recent review.
Restoration of SBS The only direct evidence for a restoration of chiral symmtery is an aligment of the vector and axial vector spectral strength. a1 is in any case hard to detect mostly , also The order parameter of chiral symmtery breaking is the four quark condensate (Weinberg sum rules) 1 ( ) qq V A 2 ss Im R ( ) s R ( ) s q q d ? But both states can acquire a huge width at the same time!
The phase diagram of nuclear matter Chemical freeze-out points derived from Statistical Hadronization Model Universal conditions for freeze-out (?) Limiting temperature Tmax? Why is it woking at low beam energies? LHC LQCD explores unknown regions from solid grounds at B=0. Tc = Tmax? 1st order phase transition Critical point ? 3 6 . 0 GeV / fm <qqbar> <gg> <(qqbar)2> Sch fer, Wambach Leupold Sch fer, Wambach priv. communication priv. communication J.Phys.G32:2199,2006 QCD inspired models demonstrate the melting of the condesates. A. Andronic, P. Braun-Munzinger, K. Redlich, J. Stachel J. Cleymans, K. Redlich
Ignorant interpretation (Cloudy Bag Model) 1 fm : equiv. to 100 MeV (uncertainty relation) q qq qq q q qq qq q q qq qq q q qq q q q q qq qq q q qq qq q q qq qq q q qq qq q
T Tc , mB ~ 0 Excitation/melting of the vacuum/cloud. smooth cross over qq qq- - qq qq- - q qq qq q qq qq- - q qq qq q q qq qq q qq qq- - qq qq- - qq qq- - q qq q q q q qq qq q q qq qq q qq qq- - qq qq- - qq qq- - q qq qq q q qq qq q
T << Tc , finite B q qq qq q q qq qq q q qq qq q qq qq- - q qq qq q q qq qq q q qq q q q q qq qq q q qq qq q
T << Tc , finite B Bag fusion 1st order q qq qq q q qq qq q q qq qq q q qq qq q q q q qq qq q q q q q q qq q q q q q q qq q
Phase diagram from large Nc Larry McLerran, QM09 conjecture for Nc = 3 Quarkyonic Matter: Confined gas of perturbative quarks!
Role of freeze-out line. Meson to baryon ratio may seperate quarkionic from non-quarkionic world. Red line from Hadron Gas Model, Sasaki QM09 meson N N = 1 baryon
Observable I Thermal dilepton rate ... 3 4 d N d dp ( ), T x ( ), x v ( ),.. x dx B coll dMdydp = 0 t t , T , 0 V 0 o ...or from transport isentropic expansion In future: use transport to generate statistical ensembles Couple hydro to transport and calculate dileptons from hydro also.
Observable II Strangeness production and equilibration. Try to seperate yields from core and corona . q qq qq q q qq qq q - - s s s s q qq qq q q qq qq q q qq qq q q qq q q q q qq qq q q qq qq q
