57 research outputs found
String Representation of Field Correlators in the SU(3)-Gluodynamics
The string representation of the Abelian projected SU(3)-gluodynamics
partition function is derived by using the path-integral duality
transformation. On this basis, we also derive analogous representations for the
generating functionals of correlators of gluonic field strength tensors and
monopole currents, which are finally applied to the evaluation of the
corresponding bilocal correlators. The large distance asymptotic behaviours of
the latter turn out to be in a good agreement with existing lattice data and
the Stochastic Model of the QCD vacuum.Comment: 11 pages, LaTeX2e, no figure
FQHE interferometers in strong tunneling regime. The role of compactness of edge fields
We consider multiple-point tunneling in the interferometers formed between
edges of electron liquids with in general different filling factors in the
regime of the Fractional Quantum Hall effect (FQHE). We derive an effective
matrix Caldeira-Leggett models for the multiple tunneling contacts connected by
the chiral single-mode FQHE edges. It is shown that the compactness of the Wen-
Fr\"ohlich chiral boson fields describing the FQHE edge modes plays a crucial
role in eliminating the spurious non-locality of the electron transport
properties of the FQHE interferometers arising in the regime of strong
tunneling.Comment: 5 page
Testing Nonperturbative Ansaetze for the QCD Field Strength Correlator
A test for the Gaussian and exponential Ansaetze for the nonperturbative
parts of the coefficient functions, D^{nonpert.} and D_1^{nonpert.}, which
parametrize the gauge-invariant bilocal correlator of the field strength
tensors in the stochastic vacuum model of QCD, is proposed. It is based on the
evaluation of the heavy-quark condensate within this model by making use of the
world-line formalism and equating the obtained result to the one following
directly from the QCD Lagrangian. This yields a certain relation between
D^{nonpert.}(0) and D_1^{nonpert.}(0), which is further compared with an
analogous relation between these quantities known from the existing lattice
data. Such a comparison leads to the conclusion that at the distances smaller
than the correlation length of the vacuum, Gaussian Ansatz is more suitable
than the exponential one.Comment: 10 pages, LaTeX2e, 1 table, no figure
Entanglement Entropy in Critical Phenomena and Analogue Models of Quantum Gravity
A general geometrical structure of the entanglement entropy for spatial
partition of a relativistic QFT system is established by using methods of the
effective gravity action and the spectral geometry. A special attention is
payed to the subleading terms in the entropy in different dimensions and to
behaviour in different states. It is conjectured, on the base of relation
between the entropy and the action, that in a fundamental theory the ground
state entanglement entropy per unit area equals , where is the
Newton constant in the low-energy gravity sector of the theory. The conjecture
opens a new avenue in analogue gravity models. For instance, in higher
dimensional condensed matter systems, which near a critical point are described
by relativistic QFT's, the entanglement entropy density defines an effective
gravitational coupling. By studying the properties of this constant one can get
new insights in quantum gravity phenomena, such as the universality of the
low-energy physics, the renormalization group behavior of , the
statistical meaning of the Bekenstein-Hawking entropy.Comment: 13 pages, published version, minor changes in the abstract, new
reference
Haldane limits via Lagrangian embeddings
In the present paper we revisit the so-called Haldane limit, i.e. a
particular continuum limit, which leads from a spin chain to a sigma model. We
use the coherent state formulation of the path integral to reduce the problem
to a semiclassical one, which leads us to the observation that the Haldane
limit is closely related to a Lagrangian embedding into the classical phase
space of the spin chain. Using this property, we find a spin chain whose limit
produces a relativistic sigma model with target space the manifold of complete
flags U(N)/U(1)^N. We discuss possible other future applications of
Lagrangian/isotropic embeddings in this context.Comment: 29 pages, 2 figure
Spinor and Isospinor Structure of Relativistic Particle Propagators
Representations by means of path integrals are used to find spinor and
isospinor structure of relativistic particle propagators in external fields.
For Dirac propagator in an external electromagnetic field all grassmannian
integrations are performed and a general result is presented via a bosonic path
integral. The spinor structure of the integrand is given explicitly by its
decomposition in the independent -matrix structures. Similar technique
is used to get the isospinor structure of the scalar particle propagator in an
external non-Abelian field.Comment: 9 pages, Preprint IC/93/197 Triest
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.
Gauge-invariant formulation of the d=3 Yang-Mills theory
We write down the Yang-Mills partition function and the average Wilson loop
in terms of local gauge-invariant variables being the six components of the
metric tensor of dual space. The Wilson loop becomes the trace of the parallel
transporter in curved space, else called the gravitational holonomy. We show
that the external coordinates mapping the 3d curved space into a flat 6d space
play the role of glueball fields, and there is a natural mechanism for the mass
gap generation.Comment: 7 page
Loop corrections to the sphaleron transition rate in the minimal standard model
The baryon number dissipation rate due to sphaleron transitions at high
temperatures in the minimal standard model is evaluated. We find that this rate
can be considerably suppressed by one loop contributions of bosonic and
fermionic fluctuations which are particularly important for a small mass of the
Higgs boson and a large top quark mass. Fixing the latter to its recently
stated value of 174 GeV the complete erasure of the baryon asymmetry is
prevented within the framework of the minimal standard model if the Higgs mass
is less than about 66 GeV.Comment: 11 pages (LaTex) plus 2 figures (uuencoded postscript files);
RUB-TPII-05/9
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