35,945 research outputs found
Quantum-classical interactions through the path integral
I consider the case of two interacting scalar fields, \phi and \psi, and use
the path integral formalism in order to treat the first classically and the
second quantum-mechanically. I derive the Feynman rules and the resulting
equation of motion for the classical field, which should be an improvement of
the usual semi-classical procedure. As an application I use this method in
order to enforce Gauss's law as a classical equation in a non-abelian gauge
theory. I argue that the theory is renormalizable and equivalent to the usual
Yang-Mills as far as the gauge field terms are concerned. There are additional
terms in the effective action that depend on the Lagrange multiplier field
\lambda that is used to enforce the constraint. These terms and their relation
to the confining properties of the theory are discussed.Comment: 16 pages, LaTeX, 1 fig, final version to appear in PR
Transport anomalies in a simplified model for a heavy electron quantum critical point
We discuss the transport anomalies associated with the development of heavy
electrons out of a neutral spin fluid using the large-N treatment of the
Kondo-Heisenberg lattice model. At the phase transition in this model the spin
excitations suddenly acquire charge. The Higgs process by which this takes
place causes the constraint gauge field to loosely ``lock'' together with the
external, electromagnetic gauge field. From this perspective, the heavy fermion
phase is a Meissner phase in which the field representing the difference
between the electromagnetic and constraint gauge field, is excluded from the
material. We show that at the transition into the heavy fermion phase, both the
linear and the Hall conductivity jump together. However, the Drude weight of
the heavy electron fluid does not jump at the quantum critical point, but
instead grows linearly with the distance from the quantum critical point,
forming a kind of ``gossamer'' Fermi-liquid.Comment: 15 pages, 3 figures. Small change in references in v
Quantum Fermion Hair
It is shown that the Dirac operator in the background of a magnetic
%Reissner-Nordstr\"om black hole and a Euclidean vortex possesses normalizable
zero modes in theories containing superconducting cosmic strings. One
consequence of these zero modes is the presence of a fermion condensate around
magnetically charged black holes which violates global quantum numbers.Comment: 16pp (harvmac (l)) and 2 figs.(not included
Persistence of inflationary shocks: Implications for West African Monetary Union Membership
Plans are far advanced to form a second monetary union, the West African Monetary Zone
(WAMZ), in Africa. While much attention is being placed on convergence criteria and
preparedness of the five aspiring member states, less attention is being placed on the extent
to which the dynamics of inflation in individual countries are (dis)similar. This paper aims to
stimulate debate on the long term sustainability of the union by examining the dynamics of
inflation within these countries. Using Fractional Integration (FI) methods, we establish that
some significant differences exist among the countries. Shocks to inflation in Sierra Leone
are non mean reverting; results for The Gambia, Ghana and Guinea-Bissau suggest some
inflation persistence, despite being mean reverting. Some policy implications are discussed
and some warnings are raised
A Second Shell in the Fornax dSph Galaxy
In the search for tidal structure in Galactic satellite systems, we have
conducted a photometric survey over a 10 square degree area centred on the
Fornax dSph galaxy. The survey was made in two colours, and the resulting
colour-magnitude data were used as a mask to select candidate Fornax RGB stars,
thereby increasing the contrast of Fornax stars to background sources in the
outer regions. Previously, we reported the presence of a shell (age 2 Gyr)
located towards the centre of Fornax. In this contribution we reveal a second
shell, significantly larger than the first, located 1.3 degrees NW from the
centre of Fornax, outside the nominal tidal radius. Moreover, the distribution
of Fornax RGB stars reveals two lobes extending to the spatial limit of our
survey, and aligned with the minor axis and with the two shells. These results
support the hypothesis of a merger between Fornax and a gas-rich companion
approximately 2 Gyr ago.Comment: Four pages,accepted for the Publications of the Astronomical Society
of Australia. Contribution the annual ASA meeting, Brisbane 200
Exploring the Dynamics of Building Supply: A Duration Model of the Development Cycle
A noticeable omission in the existing body of applied real estate research is the lack of empirical analysis of the commercial development process. We address this shortcoming by utilizing a large panel database of individual building projects that in principle allows us to follow individual projects through various stages of their development life cycle. We begin by examining the basic distributional and time series characteristics of the development cycle, and then examine how these results vary by stage of construction, property sector and geography. We then estimate unconditional transition probabilities and finally, present preliminary results from a formal, nonparametric duration model.
Q-ball formation at the deconfinement temperature in large- QCD
The deconfinement phase transition in large- QCD is studied within the
framework of an effective Polyakov-loop model, where the potential has a U(1)
symmetry originating in the large- limit of a Z-symmetric model.
At the critical temperature, the shape of the effective potential allows the
existence of Q-balls as position-dependent fluctuations of the Polyakov loop.
Q-balls with spherical or axial symmetry are numerically obtained from the
equations of motion of the effective model under consideration. The physical
properties of these non-topological solitons (mass, charge and size) are
discussed, as well as their interpretation in terms of spinning "bubbles", with
various shapes, of deconfined matter surrounded by a confined environment.Comment: 21 pages, 8 figures ; v2 matches the published versio
Gauge Group TQFT and Improved Perturbative Yang-Mills Theory
We reinterpret the Faddeev-Popov gauge-fixing procedure of Yang-Mills
theories as the definition of a topological quantum field theory for gauge
group elements depending on a background connection. This has the advantage of
relating topological gauge-fixing ambiguities to the global breaking of a
supersymmetry. The global zero modes of the Faddeev-Popov ghosts are handled in
the context of an equivariant cohomology without breaking translational
invariance. The gauge-fixing involves constant fields which play the role of
moduli and modify the behavior of Green functions at subasymptotic scales. At
the one loop level physical implications from these power corrections are gauge
invariant.Comment: 28 pages, uuencoded and compressed tar-file, LATEX+4 PS-figures, uses
psfig.sty. New appendix and some clarifying modifications, references adde
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