1,287 research outputs found
Symplectic gauge fields and dark matter
The dynamics of symplectic gauge fields provides a consistent framework for
fundamental interactions based on spin three gauge fields. One remarkable
property is that symplectic gauge fields only have minimal couplings with
gravitational fields and not with any other field of the Standard Model.
Interactions with ordinary matter and radiation can only arise from radiative
corrections. In spite of the gauge nature of symplectic fields they acquire a
mass by the Coleman-Weinberg mechanism which generates Higgs-like mass terms
where the gravitational field is playing the role of a Higgs field. Massive
symplectic gauge fields weakly interacting with ordinary matter are natural
candidates for the dark matter component of the Universe.Comment: 16 page
Vacuum Boundary Effects
The effect of boundary conditions on the vacuum structure of quantum field
theories is analysed from a quantum information viewpoint. In particular, we
analyse the role of boundary conditions on boundary entropy and entanglement
entropy. The analysis of boundary effects on massless free field theories
points out the relevance of boundary conditions as a new rich source of
information about the vacuum structure. In all cases the entropy does not
increase along the flow from the ultraviolet to the infrared.Comment: 10 page
Nodes, Monopoles and Confinement in 2+1-Dimensional Gauge Theories
In the presence of Chern-Simons interactions the wave functionals of physical
states in 2+1-dimensional gauge theories vanish at anumber of nodal points. We
show that those nodes are located at some classical configurations which carry
a non-trivial magnetic charge. In abelian gauge theories this fact explains why
magnetic monopoles are suppressed by Chern-Simons interactions. In non-abelian
theories it suggests a relevant role for nodal gauge field configurations in
the confinement mechanism of Yang-Mills theories. We show that the vacuum nodes
correspond to the chiral gauge orbits of reducible gauge fields with
non-trivial magnetic monopole components.Comment: 11 pages, revtex, no figures
Universalty and Ultraviolet Regularizations of Chern-Simons Theory
The universality of radiative corrections to the gauge coupling constant
of Chern-Simons theory is studied in a very general regularization scheme. We
show that the effective coupling constant induced by radiative corrections
depends crucially on the balance between the ultraviolet behavior of scalar and
pseudoscalar terms in the regularized action. There are three different
regimes. When the ultraviolet leading term is scalar the coupling is
shifted to .However, if the leading term is pseudoscalar the shift
is with or depending on the sign of such a term. In
the borderline case when the scalar and pseudoscalar terms have the same
ultraviolet behavior the shift of becomes arbitrary (even non-integer) and
depends on the parameters of the regularization. We also show that the
coefficient of the induced gravitational Chern-Simons term is different for the
three regimes and has the same universality properties than the effective
coupling constant . The results open the possibility of a connection with
non-rational two-dimensional conformal theories in the borderline regime.Comment: 34 pages, harvmac, no changes, 6 Postscript figures (now included
Boundary conditions: The path integral approach
The path integral approach to quantum mechanics requires a substantial
generalisation to describe the dynamics of systems confined to bounded domains.
Non-local boundary conditions can be introduced in Feynman's approach by means
of boundary amplitude distributions and complex phases to describe the quantum
dynamics in terms of the classical trajectories. The different prescriptions
involve only trajectories reaching the boundary and correspond to different
choices of boundary conditions of selfadjoint extensions of the Hamiltonian.
One dimensional particle dynamics is analysed in detail.Comment: 8 page
Attractive and Repulsive Casimir Vacuum Energy with General Boundary Conditions
The infrared behavior of quantum field theories confined in bounded domains
is strongly dependent on the shape and structure of space boundaries. The most
significant physical effect arises in the behaviour of the vacuum energy. The
Casimir energy can be attractive or repulsive depending on the nature of the
boundary. We calculate the vacuum energy for a massless scalar field confined
between two homogeneous parallel plates with the most general type of boundary
conditions depending on four parameters. The analysis provides a powerful
method to identify which boundary conditions generate attractive or repulsive
Casimir forces between the plates. In the interface between both regimes we
find a very interesting family of boundary conditions which do not induce any
type of Casimir force. We also show that the attractive regime holds far beyond
identical boundary conditions for the two plates required by the Kenneth-Klich
theorem and that the strongest attractive Casimir force appears for periodic
boundary conditions whereas the strongest repulsive Casimir force corresponds
to anti-periodic boundary conditions. Most of the analysed boundary conditions
are new and some of them can be physically implemented with metamaterials.Comment: 21 pages, 11 figure
Vacuum Nodes and Anomalies in Quantum Theories
We show that nodal points of ground states of some quantum systems with
magnetic interactions can be identified in simple geometric terms. We analyse
in detail two different archetypical systems: i) a planar rotor with a
non-trivial magnetic flux , ii) Hall effect on a torus. In the case of
the planar rotor we show that the level repulsion generated by any reflection
invariant potential is encoded in the nodal structure of the unique vacuum
for . In the second case we prove that the nodes of the first
Landau level for unit magnetic charge appear at the crossing of the two
non-contractible circles , with holonomies
for any reflection invariant potential
. This property illustrates the geometric origin of the quantum translation
anomaly.Comment: 14 pages, 2 ps-figures, to appear in Commun. Math. Phy
Perturbative quantum gauge fields on the noncommutative torus
Using standard field theoretical techniques, we survey pure Yang-Mills theory
on the noncommutative torus, including Feynman rules and BRS symmetry. Although
in general free of any infrared singularity, the theory is ultraviolet
divergent. Because of an invariant regularization scheme, this theory turns out
to be renormalizable and the detailed computation of the one loop counterterms
is given, leading to an asymptoticaly free theory. Besides, it turns out that
non planar diagrams are overall convergent when is irrational.Comment: Latex 2e, 19 pages 5 eps figures, typos corrected and 1 reference
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