6,601 research outputs found
QCD, monopoles on the Lattice and gauge invariance
The number and the location of the monopoles observed on the lattice in QCD
configurations happens to depend strongly on the choice of the gauge used to
expose them, in contrast to the physical expectation that monopoles be gauge
invariant objects. It is proved by use of the non abelian Bianchi identities
(NABI) that monopoles are indeed gauge invariant, but the method used to detect
them depends, in a controllable way, on the choice of the abelian projection.
Numerical checks are presented.Comment: 3 pages, 1 figure. Presented at the Conference QUARK CONFINEMENT AND
THE HADRON SPECTRUM IX, Madrid Aug.30-Sept.3 201
Gauge Invariance and Lattice Monopoles
The number and the location of monopoles in Lattice configurations depend on
the choice of the gauge, in contrast to the obvious requirement that monopoles,
as physical objects, have a gauge-invariant status.
It is proved, starting from non-abelian Bianchi identities, that monopoles
are indeed gauge-invariant: the technique used to detect them has instead an
efficiency which depends on the choice of the abelian projection, in a known
and well understood way.Comment: Presented at the Conference QCD@WORK10, Martina Franca (Italy) 20-23
June 2010 to appear in the proceeding
Detecting monopoles on the lattice
We address the issue why the number and the location of magnetic monopoles
detected on lattice configurations are gauge dependent, in contrast with the
physical expectation that monopoles have a gauge invariant status. By use of
the Non-Abelian Bianchi Identities we show that monopoles are gauge invariant,
but the efficiency of the technique usually adopted to detect them depends on
the choice of the gauge in a well understood way. In particular we have studied
a class of gauges which interpolates between the Maximal Abelian gauge, where
all monopoles are observed, and the Landau gauge, where all monopoles escape
detection.Comment: 5 pages, 1 ps figur
Topological Quantum Phase Transition in Synthetic Non-Abelian Gauge Potential
The method of synthetic gauge potentials opens up a new avenue for our
understanding and discovering novel quantum states of matter. We investigate
the topological quantum phase transition of Fermi gases trapped in a honeycomb
lattice in the presence of a synthetic non- Abelian gauge potential. We develop
a systematic fermionic effective field theory to describe a topological quantum
phase transition tuned by the non-Abelian gauge potential and ex- plore its
various important experimental consequences. Numerical calculations on lattice
scales are performed to compare with the results achieved by the fermionic
effective field theory. Several possible experimental detection methods of
topological quantum phase tran- sition are proposed. In contrast to condensed
matter experiments where only gauge invariant quantities can be measured, both
gauge invariant and non-gauge invariant quantities can be measured by
experimentally generating various non-Abelian gauges corresponding to the same
set of Wilson loops
The Waning of the WIMP? A Review of Models, Searches, and Constraints
Weakly Interacting Massive Particles (WIMPs) are among the best-motivated
dark matter candidates. In light of no conclusive detection signal yet despite
an extensive search program that combines, often in a complementary way,
direct, indirect, and collider probes, we find it timely to give a broad
overview of the WIMP paradigm. In particular, we review here the theoretical
foundations of the WIMP paradigm, discuss status and prospects of various
detection strategies, and explore future experimental challenges and
opportunities.Comment: 101 pages, 20 figure
Spin superfluidity and spin-orbit gauge symmetry fixing
The Hamiltonian describing 2D electron gas, in a spin-orbit active medium,
can be cast into a consistent non-Abelian gauge field theory leading to a
proper definition of the spin current. The generally advocated gauge symmetric
version of the theory results in current densities that are gauge covariant, a
fact that poses severe concerns on their physical nature. We show that in fact
the problem demands gauge fixing, leaving no room to ambiguity in the
definition of physical spin currents. Gauge fixing also allows for polarized
edge excitations not present in the gauge symmetric case. The scenario here is
analogous to that of superconductivity gauge theory. We develop a variational
formulation that accounts for the constraints between U(1) physical fields and
SU(2) gauge fields and show that gauge fixing renders a physical matter and
radiation currents and derive the particular consequences for the Rashba SO
interaction.Comment: to appear in EP
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