2,531 research outputs found
Spontaneous Parity Violation
We disprove the Vafa-Witten theorem on the impossibility of spontaneously
breaking parity in vector-like gauge field theories, identifying a mechanism
driven by quantum fluctuations. With the introduction of a meromorphic Lattice
formulation, defined over 5 dimensions, we demonstrate that the minima of the
free energy can be distinct from the maxima of the partition function :
identifying and evaluating a suitable contour for the partition function
defined such that asymptotic behaviour of the complex action is
non-oscillatory.Comment: 6 page
Lorentz Covariance and the Dimensional Crossover of 2d-Antiferromagnets
We derive a lattice -function for the 2d-Antiferromagnetic Heisenberg
model, which allows the lattice interaction couplings of the nonperturbative
Quantum Monte Carlo vacuum to be related directly to the zero-temperature fixed
points of the nonlinear sigma model in the presence of strong interplanar and
spin anisotropies. In addition to the usual renormalization of the gapful
disordered state in the vicinity of the quantum critical point, we show that
this leads to a chiral doubling of the spectra of excited states
Exact Nonperturbative Renormalization
We propose an exact renormalization group equation for Lattice Gauge
Theories, that has no dependence on the lattice spacing. We instead relate the
lattice spacing properties directly to the continuum convergence of the support
of each local plaquette. Equivalently, this is formulated as a convergence
prescription for a characteristic polynomial in the gauge coupling that allows
the exact meromorphic continuation of a nonperturbative system arbitrarily
close to the continuum limit.Comment: 12 page
The Lattice -function of Quantum Spin Chains
We derive the lattice -function for quantum spin chains, suitable for
relating finite temperature Monte Carlo data to the zero temperature fixed
points of the continuum nonlinear sigma model. Our main result is that the
asymptotic freedom of this lattice -function is responsible for the
nonintegrable singularity in , that prevents analytic continuation
between and .Comment: 10 page
A scanning drift tube apparatus for spatio-temporal mapping of electron swarms
A "scanning" drift tube apparatus, capable of mapping of the spatio-temporal
evolution of electron swarms, developing between two plane electrodes under the
effect of a homogeneous electric field, is presented. The electron swarms are
initiated by photoelectron pulses and the temporal distributions of the
electron flux are recorded while the electrode gap length (at a fixed electric
field strength) is varied. Operation of the system is tested and verified with
argon gas, the measured data are used for the evaluation of the electron bulk
drift velocity. The experimental results for the space-time maps of the
electron swarms - presented here for the first time - also allow clear
observation of deviations from hydrodynamic transport. The swarm maps are also
reproduced by particle simulations
An Open Source Linked Data Framework for Publishing Environment Data under the UK Location Strategy
Not in my back yard! Sports stadia location and the property market
In recent years sports stadia have been built in the UK, not only for their intended sporting purpose but with the twin aim of stimulating economic and physical regeneration. However, proposals to locate stadia in urban areas often prompt a negative reaction from local communities, fearing a decline in property prices. This paper will use a case study of the Millennium Stadium in Cardiff and the City of Manchester Stadium to illustrate that in contrast to this widely held belief, sports stadia can actually enhance the value of residential property. Furthermore, it will argue that stadia also contribute indirectly to property value through the creation of pride, confidence and enhanced image of an area.</p
Sport in the city: measuring economic significance at the local level
In many cities throughout Europe, sport is increasingly being used as a tool for economic revitalisation. While there has been a growth in literature relating to the specific economic impacts of sports-led development, including professional sport facilities, teams, and sport events, limited research has been undertaken on the contribution of the whole sport sector to output and employment. In the United Kingdom (UK), studies have focused on evaluating sport-related economic activity at the national level, yet despite the increasing use of sport for local economic development little research has been undertaken at the city level. To address this situation, this article uses the National Income Accounting framework to measure the economic importance of sport in Sheffield, UK. It shows that the value-added in 1996/97 was 165.61m or 4.11% of Gross Domestic Product (GDP), approximately twice the amount predicted from current national estimates. It is argued that this can primarily be explained by previous studies under-estimating the economic importance of sport, largely due to methodological differences. It goes on to suggest that future research on the significance of sport should be undertaken at the local level to provide policymakers with information at the spatial level where regeneration programmes are being implemented.</p
On the possibility to supercool molecular hydrogen down to superfluid transition
Recent calculations by Vorobev and Malyshenko (JETP Letters, 71, 39, 2000)
show that molecular hydrogen may stay liquid and superfluid in strong electric
fields of the order of . I demonstrate that strong local
electric fields of similar magnitude exist beneath a two-dimensional layer of
electrons localized in the image potential above the surface of solid hydrogen.
Even stronger local fields exist around charged particles (ions or electrons)
if surface or bulk of a solid hydrogen crystal is statically charged.
Measurements of the frequency shift of the photoresonance transition
in the spectrum of two-dimensional layer of electrons above positively or
negatively charged solid hydrogen surface performed in the temperature range 7
- 13.8 K support the prediction of electric field induced surface melting. The
range of surface charge density necessary to stabilize the liquid phase of
molecular hydrogen at the temperature of superfluid transition is estimated.Comment: 5 pages, 2 figure
The pseudo-Goldstone spectrum of 2-colour QCD at finite density
We examine the spectrum of 2-colour lattice QCD with 4 continuum flavours at
a finite chemical potential () for quark-number, on a
lattice. First we present evidence that the system undergoes a transition to a
state with a diquark condensate, which spontaneously breaks quark number at
, and that this transition is mean field in nature. We then
examine the 3 states that would be Goldstone bosons at for zero Dirac
and Majorana quark masses. The predictions of chiral effective Lagrangians give
a good description of the behaviour of these masses for . Except
for the heaviest of these states, these predictions diverge from our
measurements, once is significantly greater than . However, the
qualitative behaviour of these masses, indicates that the physics is very
similar to that predicted by these effective Lagrangians, and there is some
indication that at least part of these discrepancies is due to saturation, a
lattice artifact.Comment: 32 pages LaTeX/Revtex, 8 Postscript figure
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