178 research outputs found
Deconfinement, Monopoles and New Phenomena in Heavy Ion Collisions
We discuss various manifestations of the "magnetic scenario" for the
quark-gluon plasma viewed as a mixture of two plasmas, of electrically (quark
and gluons) as well as magnetically charged quasiparticles. Near the
deconfinement phase transition, very small density of free
quarks should lead to negligible screening of electric field while magnetic
screening remains strong. The consequence of this should be existence of a
"corona" of the QGP, in a way similar to that of the Sun, in which electric
fields influence propagation of perturbations and even form metastable flux
tubes. The natural tool for its description is (dual) magnetohydrodynamics:
among observable consequences is splitting of sound into two modes, with larger
and smaller velocity. The latter can be zero, hinting for formation of
pressure-stabilized flux tubes. Remarkably, recent experimental discoveries at
RHIC show effects similar to expected for "corona structures". In dihadron
correlation function with large- trigger there are a "cone" and a "hard
ridge",while the so called "soft ridge" is a similar structure seen without
hard trigger. They seem to be remnants of flux tubes, which -- contrary to
naive expectations -- seem to break less often in near- matter than do
confining strings in vacuum.Comment: Written version of talk given at "Shifmania" conference, June 2009,
Minneapolis, related to 60-the birthday of Misha Shifma
Recent progress in understanding deconfinement and chiral restoration phase transitions
Paradigme shift in gauge topology, from instantons to their constituents --
instanton-dyons -- has recently lead to very significant advances. Like
instantons, they have fermionic zero modes, and their collectivization at
sufficiently high density explains the chiral symmetry breaking. Unlike
instantons, these objects have electric and magnetic charges. Their back
reaction on the mean value of the Polyakov line (holonomy) allows to explain
the deconfinement transition. The talk summarizes recent works on the dyon
ensemble, done in the mean field approximation (MFA), and also by direct
numerical statistical simulation. Introduction of non-trivial quark periodicity
conditions leads to drastic changes in both deconfinement and chiral
transitions. In particulaly, in the so called Z(N_c)-QCD model the former gets
much stronger, while the latter does not seem to occur at all.Comment: XIIth Quark Confinement and the Hadron Spectrum, 28 Aug to 4 Sep 201
Comments on the CMS discovery of the "Ridge" in High Multiplicity pp collisions at LHC
A very recent paper by the CMS collaboration \cite{cms_ridge} has created
large discussion in the media, which call it important but did not explain why,
in some places even calling it "unundestandable". While it is of course too
soon to know what causes the correlations in question, a very similar
observation in heavy ion collisions at RHIC has rather simple explanation
related to explosion of high energy density matter. Perhaps this observation is
the first hint for an explosive behavior in pp, which was anticipated and
looked for for decades, yet never been seen
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