9,520 research outputs found
Theta Dependence In The Large N Limit Of Four-Dimensional Gauge Theories
The theta dependent of pure gauge theories in four dimensions can be studied
using a duality of large N gauge theories with string theory on a certain
spacetime. Via this duality, one can argue that for every theta, there are
infinitely many vacua that are stable in the large N limit. The true vacuum,
found by minimizing the energy in this family, is a smooth function of theta
except at theta equal to pi, where it jumps. This jump is associated with
spontaneous breaking of CP symmetry. Domain walls separating adjacent vacua are
described in terms of wrapped sixbranes.Comment: 8 p
On Induced Gravity in 2-d Topological Theories
We study 2-d gauge theories with the objective to understand, also
at the quantum level, the emergence of induced gravity. The wave functionals -
representing the eigenstates of a vanishing flat potential - are obtained in
the representation. The composition of the space they describe is then
analyzed: the state corresponding to the singlet representation of the gauge
group describes a topological universe. For other representations a metric
which is invariant under the residual gauge group is induced, apart from
possible topological obstructions. Being inherited from the group metric it is
rather rigid.Comment: 38, tex, 160/93/e
Wu-Yang Monopoles and Non-Abelian Seiberg-Witten Equations
Some exact solutions of the SU(2) Seiberg-Witten equations in Minkowski
spacetime are given.Comment: 6 pages, LATEX file, no figures. To appear in Mod. Phys. Lett.
Universal Ratios of Characteristic Lengths in Semidilute Polymer Solutions
We use experimental and simulation data from the literature to infer five
characteristic lengths, denoted , , , , and
of a semidilute polymer solution. The first two of these are defined in
terms of scattering from the solution, the third is defined in terms of osmotic
pressure, the fourth by the spatial monomer concentration profile, and the last
by co-operative diffusion. In a given solution the ratios of any of these five
lengths are expected to be universal constants. Knowing these constants thus
allows one to use one measured property of a solution as a means of inferring
others. We calculate these ratios and estimate their uncertainties for
solutions in theta as well as good-solvent conditions. The analysis is
strengthened by use of scattering properties of isolated polymers inferred from
computer simulations.Comment: 15 pages(pdf), to be submitted to Macromolecules or J. Chem. Phy
Making Nuclei Out Of The Skyrme Crystal
A new method for approximating Skyrme solutions is developed. It consists of
cutting sections out of the Skyrme crystal and smoothly interpolating between
the boundary and spatial infinity. Several field configurations are
constructed, and their energies calculated. The surface energy (per unit area)
of an infinite flat plane of the crystal is also calculated, and the result
used to derive a formula analogous to the semi-empirical mass formula of
nuclear physics. This formula can be used to give some idea of what the Skyrme
model predicts about volume and surface energies of the nucleus over a broad
range of baryon numbers.Comment: 20 pages, uuencoded ps file `crystal.uu'. The LaTeX version can be
obtained by emailing [email protected] or [email protected]
The polymer mat: Arrested rebound of a compressed polymer layer
Compression of an adsorbed polymer layer distorts its relaxed structure.
Surface force measurements from different laboratories show that the return to
this relaxed structure after the compression is released can be slowed to the
scale of tens of minutes and that the recovery time grows rapidly with
molecular weight. We argue that the arrested state of the free layer before
relaxation can be described as a Guiselin brush structure1, in which the
surface excess lies at heights of the order of the layer thickness, unlike an
adsorbed layer. This brush structure predicts an exponential falloff of the
force at large distance with a decay length that varies as the initial
compression distance to the 6/5 power. This exponential falloff is consistent
with surface force measurements. We propose a relaxation mechanism that
accounts for the increase in relaxation time with chain length.Comment: 24 pages, 5 figre
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