3,108 research outputs found
Competition of Color Ferromagnetic and Superconductive States in a Quark-Gluon System
The possibility of color ferromagnetism in an SU(2) gauge field model is
investigated. The conditions allowing a stable color ferromagnetic state of the
quark system in the chromomagnetic field occupying small domains are
considered. A phase transition between this state and the color superconducting
state is considered. The effect of finite temperature is analyzed.Comment: 21 pages, 4 Postscript figure
Magnetic Oscillations in the Nambu - Jona-Lasinio model
The phase structure of a simple Nambu-Jona-Lasinio model has been
investigated at non-zero values of and H, where H is an external magnetic
field and is the chemical potential. On this basis magnetic oscillations
effects were considered. It was shown that there are standard (periodic) van
Alphen-de Haas magnetic oscillations of some thermodynamical quantities,
including magnetization, pressure and particle density in the NJL system.
Besides, we have found non-standard, i.e. non-periodic, magnetic oscillations,
since the frequency of oscillations is a H-dependent quantity. Finally, there
arises an oscillating behaviour not only for thermodynamical quantities, but
also for a dynamical quantity like the quark mass. The possibility for magnetic
oscillations of some physical quantities inside neutron stars is discussed.Comment: RevTeX, 12 pages; Talk given by K.G. Klimenko at the International
Workshop on Hadron Physics, 10-15 September 1999, Coimbra, Portuga
Diquarks in the color--flavor locked phase of dense quark matter
Diquark excitations of dense quark matter are considered in the framework of
the Nambu -- Jona-Lasinio model with three types of massless quarks in the
presense of a quark number chemical potential . We investigate the
effective action of meson- and diquark fields at sufficiently high values of
, where the color--flavor locked (CFL) phase is realized, and prove the
existence of NG-bosons in the sector of pseudoscalar diquarks. In the sector of
scalar diquarks an additional NG-boson is found, corresponding to the
spontaneous breaking of the U(1) baryon symmetry in the CFL phase. Finally,
the existence of massive scalar and pseudoscalar diquark excitations is
demonstrated.Comment: 10 pages, 2 figures; version accepted for publication in PR
Dressed Polyakov loop and phase diagram of hot quark matter under magnetic field
We evaluate the dressed Polyakov loop for hot quark matter in strong magnetic
field. To compute the finite temperature effective potential, we use the
Polyakov extended Nambu-Jona Lasinio model with eight-quark interactions taken
into account. The bare quark mass is adjusted in order to reproduce the
physical value of the vacuum pion mass. Our results show that the dressed
Polyakov loop is very sensitive to the strenght of the magnetic field, and it
is capable to capture both the deconfinement crossover and the chiral
crossover. Besides, we compute self-consistently the phase diagram of the
model. We find a tiny split of the two aforementioned crossovers as the
strength of the magnetic field is increased. Concretely, for the largest value
of magnetic field investigated here, , the split is of the order
of . A qualitative comparison with other effective models and recent
Lattice results is also performed.Comment: 10 pages, 3 figures, RevTeX4-1 styl
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