57 research outputs found
Higgs-inspired corrections to the RG flow in the finite-temperature 3D Georgi-Glashow model and its SU(N)-generalization
The Berezinsky-Kosterlitz-Thouless (BKT) RG flow in the ensemble of monopoles
existing in the finite-temperature (2+1)D Georgi-Glashow model is explored in
the regime when the Higgs field is not infinitely heavy, but its mass is rather
of the same order of magnitude as the mass of the W-boson. The corrections to
the standard RG flow are derived to the leading order in the inverse mass of
the Higgs boson. According to the obtained RG equations, the scaling of the
free-energy density in the critical region and the value of the critical
temperature of the phase transition are found to be unaffected by the
finiteness of the Higgs-boson mass. The evolution of the Higgs mass itself is
also investigated and shown to be rather weak, that enables one to treat this
parameter as a constant. The same analysis is further performed in the
SU(N)-case at N>2, where the RG invariance is demonstrated to hold only
approximately, in a certain sense. Modulo this approximation, the critical
behaviour of the SU(N)-model turns out to be identical to that of the
SU(2)-one.Comment: 12 pages, LaTeX2e, no figure
Nonperturbative QCD vacuum and Colour Superconductivity
We discuss the possibility of existence of colour superconducting state in
real QCD vacuum with nonzero gluon condensate. We argue, that nonperturbative
gluonic fields might play a crucial role in colour superconductivity scenario.Comment: LaTeX, 12 pages, reference adde
Chiral thermodynamics in a magnetic field
We study thermodynamic properties of the QCD vacuum in a magnetic field below
chiral phase transition. The hadronic phase free energy in a constant
homogeneous magnetic field is calculated in the framework of the chiral
perturbation theory at non-zero pionic mass. It is demonstrated that the order
parameter of the chiral phase transition remains constant provided temperature
and magnetic field strength are related through obtained equation (the
phenomenon of ''quark condensate freezing'').Comment: RevTeX4, 9 pages, no figure
BCS-Bose Crossover in Color Superconductivity
It is shown that the onset of the color superconducting phase occurs in the
BCS-BE crossover region.Comment: 5 pages, LaTeX, references adde
Nature of the deconfining phase transition in the 2+1-dimensional SU(N) Georgi-Glashow model
The nature of the deconfining phase transition in the 2+1-dimensional SU(N)
Georgi-Glashow model is investigated. Within the dimensional-reduction
hypothesis, the properties of the transition are described by a two-dimensional
vectorial Coulomb gas models of electric and magnetic charges. The resulting
critical properties are governed by a generalized SU(N) sine-Gordon model with
self-dual symmetry. We show that this model displays a massless flow to an
infrared fixed point which corresponds to the Z parafermions conformal
field theory. This result, in turn, supports the conjecture of Kogan, Tekin,
and Kovner that the deconfining transition in the 2+1-dimensional SU(N)
Georgi-Glashow model belongs to the Z universality class.Comment: 12 page
Deconfining phase transition in the 3D Georgi-Glashow model with finite Higgs-boson mass
The (2+1)D Georgi-Glashow model is explored at finite temperature in the
regime when the Higgs boson is not infinitely heavy. The resulting
Higgs-mediated interaction of monopoles leads to the appearance of a certain
upper bound for the parameter of the weak-coupling approximation. Namely, when
this bound is exceeded, the cumulant expansion used for the average over the
Higgs field breaks down. The finite-temperature deconfining phase transition
with the account for the same Higgs-mediated interaction of monopoles is
further analysed. It is demonstrated that in the general case, accounting for
this interaction leads to the existence of two distinct phase transitions
separated by the temperature region where W-bosons exist in both, molecular and
plasma, phases. The dependence of possible ranges of the critical temperatures
corresponding to these phase transitions on the parameters of the
Georgi-Glashow model is discussed. The difference in the RG behaviour of the
fugacity of W-bosons from the respective behaviour of this quantity in the
compact-QED limit of the model is finally pointed out.Comment: 9 pages, LaTeX2e, no figures, to appear in Phys. Lett.
The chicken or the egg; or Who ordered the chiral phase transition?
We draw an analogy between the deconfining transition in the 2+1 dimensional
Georgi-Glashow model and the chiral phase transition in 3+1 dimensional QCD.
Based on the detailed analysis of the former (hep-th/0010201) we suggest that
the chiral symmetry restoration in QCD at high temperature is driven by the
thermal ensemble of baryons and anti-baryons. The chiral symmetry is restored
when roughly half of the volume is occupied by the baryons. Surprisingly
enough, even though baryons are rather heavy, a crude estimate for the critical
temperature gives Mev. In this scenario the binding of the instantons
is not the cause but rather a consequence of the chiral symmetry restoration.Comment: 22 pages, 7 figures, comments about chiral symmetry at finite nuclear
density are adde
A lattice study of 3D compact QED at finite temperature
We study the deconfinement phase transition and monopole properties in the
finite temperature 3D compact Abelian gauge model on the lattice. We predict
the critical coupling as function of the lattice size in a simplified model to
describe monopole binding. We demonstrate numerically that the monopoles are
sensitive to the transition. In the deconfinement phase the monopoles appear in
the form of a dilute gas of magnetic dipoles. In the confinement phase both
monopole density and string tension differ from semiclassical estimates if
monopole binding is neglected. However, the analysis of the monopole clusters
shows that the relation between the string tension and the density of monopoles
in charged clusters is in reasonable agreement with those predictions. We study
the cluster structure of the vacuum in both phases of the model.Comment: 18 pages, 14 EPS figures, LaTeX uses epsfig.st
Clustering of Monopoles in the Instanton Vacuum
We generate a random instanton vacuum with various densities and size
distributions. We perform numerically the maximally abelian gauge fixing of
these configurations in order to find monopole trajectories induced by
instantons. We find that instanton-induced monopole loops form enormous
clusters occupying the whole physical volume, provided instantons are
sufficiently dense. It indicates that confinement might be caused by
instantons.Comment: 7 pages, Plain Latex, (3 figures - available on request from
[email protected]
Interaction of electric charges in (2+1)D magnetic dipole gas
The interaction of electrically charged particles in a dilute gas of
point--like magnetic dipoles is studied. We show that the interaction potential
at small distances has a linear piece due to overlap of the dipole clouds
gathered near electric sources. At large distances the potential becomes of the
Coulomb type with non-perturbatively renormalized charge of the test particle.
The physical applications of these results are discussed.Comment: 23 pages, 12 EPS figures, RevTeX, uses epsfig.sty; misprints
corrected (to appear in Phys.Rev.D
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