3 research outputs found
Lattice QCD Simulations in External Background Fields
We discuss recent results and future prospects regarding the investigation,
by lattice simulations, of the non-perturbative properties of QCD and of its
phase diagram in presence of magnetic or chromomagnetic background fields.
After a brief introduction to the formulation of lattice QCD in presence of
external fields, we focus on studies regarding the effects of external fields
on chiral symmetry breaking, on its restoration at finite temperature and on
deconfinement. We conclude with a few comments regarding the effects of
electromagnetic background fields on gluodynamics.Comment: 31 pages, 10 figures, minor changes and references added. To appear
in Lect. Notes Phys. "Strongly interacting matter in magnetic fields"
(Springer), edited by D. Kharzeev, K. Landsteiner, A. Schmitt, H.-U. Ye
Magnetic Catalysis: A Review
We give an overview of the magnetic catalysis phenomenon. In the framework of
quantum field theory, magnetic catalysis is broadly defined as an enhancement
of dynamical symmetry breaking by an external magnetic field. We start from a
brief discussion of spontaneous symmetry breaking and the role of a magnetic
field in its a dynamics. This is followed by a detailed presentation of the
essential features of the phenomenon. In particular, we emphasize that the
dimensional reduction plays a profound role in the pairing dynamics in a
magnetic field. Using the general nature of underlying physics and its
robustness with respect to interaction types and model content, we argue that
magnetic catalysis is a universal and model-independent phenomenon. In support
of this claim, we show how magnetic catalysis is realized in various models
with short-range and long-range interactions. We argue that the general nature
of the phenomenon implies a wide range of potential applications: from certain
types of solid state systems to models in cosmology, particle and nuclear
physics. We finish the review with general remarks about magnetic catalysis and
an outlook for future research.Comment: 37 pages, to appear in Lect. Notes Phys. "Strongly interacting matter
in magnetic fields" (Springer), edited by D. Kharzeev, K. Landsteiner, A.
Schmitt, H.-U. Yee. Version 2: references adde
Domain wall network as QCD vacuum and the chromomagnetic trap formation under extreme conditions
The ensemble of Euclidean gluon field configurations represented by the
domain wall network is considered. A single domain wall is given by the
sine-Gordon kink for the angle between chromomagnetic and chromoelectric
components of the gauge field. The domain wall separates the regions with
self-dual and anti-self-dual fields. The network of the domain wall defects is
introduced as a combination of multiplicative and additive superpositions of
kinks. The character of the spectrum and eigenmodes of color-charged
fluctuations in the presence of the domain wall network is discussed. The
concept of the confinement-deconfinement transition in terms of the ensemble of
domain wall networks is outlined. Conditions for the formation of thick domain
wall junction during heavy ion collisions are discussed, and the spectrum of
color charged quasiparticles inside the trap is evaluated. An important
observation is the existence of the critical size of the trap stable
against gluon tachyonic modes, which means that deconfinement can occur only in
a finite region of space-time in principle. The size is related to the
value of gluon condensate .Comment: 20 pages, 10 figure