2,684 research outputs found
Finite-temperature chiral condensate and low-lying Dirac eigenvalues in quenched SU(2) lattice gauge theory
The spectrum of low-lying eigenvalues of overlap Dirac operator in quenched
SU(2) lattice gauge theory with tadpole-improved Symanzik action is studied at
finite temperatures in the vicinity of the confinement-deconfinement phase
transition defined by the expectation value of the Polyakov line. The value of
the chiral condensate obtained from the Banks-Casher relation is found to drop
down rapidly at T = Tc, though not going to zero. At Tc' = 1.5 Tc = 480 MeV the
chiral condensate decreases rapidly one again and becomes either very small or
zero. At T < Tc the distributions of small eigenvalues are universal and are
well described by chiral orthogonal ensemble of random matrices. In the
temperature range above Tc where both the chiral condensate and the expectation
value of the Polyakov line are nonzero the distributions of small eigenvalues
are not universal. Here the eigenvalue spectrum is better described by a
phenomenological model of dilute instanton - anti-instanton gas.Comment: 8 pages RevTeX, 5 figures, 2 table
Numerical study of chiral magnetic effect in quenched SU(2) lattice gauge theory
A possible experimental observation of the chiral magnetic effect in heavy
ion collisions at RHIC was recently reported by the STAR Collaboration. We
study signatures of this effect in SU(2) lattice gluodynamics with the chirally
invariant Dirac operator. We find that at zero temperature the local
fluctuations of an electric current of quarks and chirality fluctuations
increase with external Abelian magnetic field. The external magnetic field
leads to spatial separation of the quark's electric charges. The separation
increases with the strength of the magnetic field. As temperature gets higher
the dependence of these quantities on the strength of the magnetic field
becomes weaker. In the deconfinement phase the local fluctuations of the chiral
density and of the spatial components of the quarks electric current are large
and are almost independent on the external magnetic field. The local
fluctuations of the electric charge density decrease with the strength of the
magnetic field in this phase.Comment: 7 pages, 8 figures; Presented at 27th International Symposium on
Lattice Field Theory, Beijing, China, 25 Jul -31 Jul 2009; revision: minor
stylistic change
Monopoles and Confining Strings in QCD
We review the recent results in the physics of the magnetic monopoles in
gluodynamics and a dual formulation of non-Abelian theories, relevant to the
physics of the confinement. It occurs that the dual gluon is a U(1) gauge
boson, despite of the fact that usual gluons are non-Abelian. The effective
infrared Lagrangian for gluodynamics is suggested which leads to the Casimir
scaling of the string tension for quarks in various representations. We also
show that the results of the calculations in lattice gauge theories confirm our
theoretical predictions.Comment: 36 pp., Latex2e, 9 figures (epsfig). Review based on the plenary
talks of M.I.Polikarpov at International Conference "Supersymmetry and
Quantum Field Theory", dedicated to the 75th birthday anniversary of Dmitrij
Volkov (NSC KIPT, Kharkov, Ukraine 25 - 29 July, 2000) and XVIII CFIF Autumn
School "Topology of strongly correlated systems" (Lisbon 8-13 October 2000
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