1,777 research outputs found
1+1 Dimensional Yang-Mills Theories in Light-Cone Gauge
In 1+1 dimensions two different formulations exist of SU(N) Yang Mills
theories in light-cone gauge; only one of them gives results which comply with
the ones obtained in Feynman gauge. Moreover the theory, when considered in
1+(D-1) dimensions, looks discontinuous in the limit D=2. All those features
are proven in Wilson loop calculations as well as in the study of the
bound state integral equation in the large N limit.Comment: Invited report at the Workshop "Low Dimensional Field Theory",
Telluride (CO), Aug. 5-17 1996; 16 pages, latex, no figures To appear in
International Journal of Modern Physics A minor misprints correcte
Zero Modes and Conformal Anomaly in Liouville Vortices
The partition function of a two dimensional Abelian gauge model reproducing
magnetic vortices is discussed in the harmonic approximation. Classical
solutions exhibit conformal invariance, that is broken by statistical
fluctuations, apart from an exceptional case. The corresponding ``anomaly'' has
been evaluated. Zero modes of the thermal fluctuation operator have been
carefully discussed.Comment: RevTex, 14 pages, no figures. To appear on Nucl. Phys.
interaction in light-cone gauge formulations of Yang-Mills theory in 1+1 dimensions
A rectangular Wilson loop with sides parallel to space and time directions is
perturbatively evaluated in two light-cone gauge formulations of Yang-Mills
theory in 1+1 dimensions, with ``instantaneous'' and ``causal'' interactions
between static quarks. In the instantaneous formulation we get Abelian-like
exponentiation of the area in terms of . In the ``causal'' formulation the
loop depends not only on the area, but also on the dimensionless ratio , and being the lengths of the rectangular sides. Besides
it also exhibits dependence on . In the limit the area law
is recovered, but dependence on survives. Consequences of these results
are pointed out.Comment: 30 pages, latex, one figure included as a ps file, an Erratum
include
Time exponentiation of a Wilson loop for Yang-Mills theories in 2+\epsilon dimensions
A rectangular Wilson loop centered at the origin, with sides parallel to
space and time directions and length and respectively, is
perturbatively evaluated in Feynman gauge for Yang--Mills
theory in dimensions. When , there is a dependence on the
dimensionless ratio , besides the area. In the limit ,
keeping , the leading expression of the loop involves only the Casimir
constant of the fundamental representation and is thereby in agreement
with the expected Abelian-like time exponentiation (ALTE). At the result
depends also on , the Casimir constant of the adjoint representation and a
pure area law behavior is recovered, but no agreement with ALTE in the limit
. Consequences of these results concerning two and
higher-dimensional gauge theories are pointed out.Comment: RevTex, 28 pages, two figure files include
Is porto sinusoidal vascular disease to be actively searched in patients with portal vein thrombosis?
Porto sinusoidal vascular liver disease (PSVD) and portal vein thrombosis (PVT) are distinct vascular liver diseases characterized, respectively, by an intrahepatic and a prehepatic obstacle to the flow in the liver portal system. PVT may also occur as a complication of the natural history of PSVD, especially if a prothrombotic condition coexists. In other cases, it is associated to local and systemic pro-thrombotic conditions, even if its cause remains unknown in up to 25% despite an active search. In our opinion, the presence of PSVD should be suspected in patients with PVT especially in those with PVT "sine causa" and the active search of this condition should be included in their diagnostic work-out. However, sometimes the diagnosis of pre-existing PSVD is very hard. Biopsy cannot be fully discriminant as similar histological data have been described in both conditions. Liver stiffness may help as it has been shown to be higher in PSVD than in "pure" PVT, due to the presence of sclerosis in the portal venous radicles observable in PSVD patients. Nevertheless, comparing liver stiffness between PVT and PSVD has until now been restricted to very limited series of patients. In conclusion, even if it is still totally hypothetical, our point of view may have clinical consequences, especially when deciding to perform a liver biopsy in patients with a higher liver stiffness and suspending the anticoagulation in patients with PVT and no detectable prothrombotic factors
Nonlocal gravity and the diffusion equation
We propose a nonlocal scalar-tensor model of gravity with pseudodifferential
operators inspired by the effective action of p-adic string and string field
theory on flat spacetime. An infinite number of derivatives act both on the
metric and scalar field sector. The system is localized via the diffusion
equation approach and its cosmology is studied. We find several exact dynamical
solutions, also in the presence of a barotropic fluid, which are stationary in
the diffusion flow. In particular, and contrary to standard general relativity,
there exist solutions with exponential and power-law scale factor also in an
open universe, as well as solutions with sudden future singularities or a
bounce. Also, from the point of view of quantum field theory, spontaneous
symmetry breaking can be naturally realized in the class of actions we
consider.Comment: 18 pages, 5 figures. v2: typos corrected, references added. Major
changes are an expansion of the discussion of homogeneous perturbations and
the inclusion of cosmological fluids in the dynamic
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