DECONFINEMENT, MONOPOLES AND NEW PHENOMENA IN HEAVY ION COLLISIONS

摘要

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, T ≈ Tc 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-pt 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-Tc matter than do confining strings in vacuum.