21,024 research outputs found
Magnetic condensation, Abelian dominance and instability of Savvidy vacuum
We show that a certain type of color magnetic condensation originating from
magnetic monopole configurations is sufficient to provide the mass for
off-diagonal gluons in the SU(2) Yang-Mills theory under the
Cho--Faddeev--Niemi decomposition. We point out that the generated gluon mass
can cure the instability of the Savvidy vacuum. In fact, such a novel type of
magnetic condensation is shown to occur by calculating the effective potential.
This enables us to explain the infrared Abelian dominance and monopole
dominance by way of a non-Abelian Stokes theorem, which suggests the dual
superconductivity picture of quark confinement. Finally, we discuss the
implication to the Faddeev-Skyrme model with knot soliton as a low-energy
effective theory of Yang-Mills theory.Comment: 14 pages, 2 figures; a version accepted in Phys. Lett. B, Main
changes in sections 2.5 and 2.6. in order to explain the crucial idea bette
The `BRST-invariant' Condensate of Dimension Two in QCD
The status of the `BRST-invariant' condensate of mass dimension two in QCD is
explained. The condensate is only invariant under an `on-shell' BRST symmetry
which includes a partial gauge-fixing. The on-shell BRST symmetry represents
the residual gauge symmetry under gauge transformations which preserve the
partial gauge fixing. The gauge-invariant operators which correspond to the
BRST-invariant condensate are identified in the Lorentz and maximal Abelian
gauges and are shown to be invariant under the residual gauge transformations.Comment: 6 page
Reformulating SU(N) Yang-Mills theory based on change of variables
We propose a new version of SU(N) Yang-Mills theory reformulated in terms of
new field variables which are obtained by a nonlinear change of variables from
the original Yang-Mills gauge field. The reformulated Yang-Mills theory enables
us to study the low-energy dynamics by explicitly extracting the topological
degrees of freedom such as magnetic monopoles and vortices to clarify the
mechanism for quark confinement.
The dual superconductivity in Yang-Mills theory is understood in a
gauge-invariant manner, as demonstrated recently by a non-Abelian Stokes
theorem for the Wilson loop operator, although the basic idea of this
reformulation is based on the Cho-Faddeev-Niemi decomposition of the gauge
potential.Comment: 51 pages, 1 figure; version to be published in Prog. Theor. Phys.
Vol. 120, No.1 (2008
Yang-Mills theory constructed from Cho--Faddeev--Niemi decomposition
We give a new way of looking at the Cho--Faddeev--Niemi (CFN) decomposition
of the Yang-Mills theory to answer how the enlarged local gauge symmetry
respected by the CFN variables is restricted to obtain another Yang-Mills
theory with the same local and global gauge symmetries as the original
Yang-Mills theory. This may shed new light on the fundamental issue of the
discrepancy between two theories for independent degrees of freedom and the
role of the Maximal Abelian gauge in Yang-Mills theory. As a byproduct, this
consideration gives new insight into the meaning of the gauge invariance and
the observables, e.g., a gauge-invariant mass term and vacuum condensates of
mass dimension two. We point out the implications for the Skyrme--Faddeev
model.Comment: 17pages, 1 figure; English improved; a version appeared in Prog.
Theor. Phy
Vacuum condensate of mass dimension 2 as the origin of mass gap and quark confinement (A review)
This is a brief summary of recent works on the possibility of vacuum
condensate of mass dimension 2 in Yang-Mills theory as the gluon sector of QCD.
In particular, I discuss the physical implications due to this condensate,
especially, for the mass gap and quark confinement. This talk is mainly based
on a recent paper [1] and papers in preparation [2].Comment: 13 pages, no figures, Talk presented at the workshop ``Structure and
Reaction of Hadrons based on non-perturbative QCD" held at the Research
Center of Nuclear Physics (RCNP), Osaka University, Japan, 23-24 July 200
The exact decomposition of gauge variables in lattice Yang-Mills theory
In this paper, we consider lattice versions of the decomposition of the Yang-
Mills field a la Cho-Faddeev-Niemi, which was extended by Kondo, Shinohara and
Murakami in the continuum formulation. For the SU(N) gauge group, we propose a
set of defining equations for specifying the decomposition of the gauge link
variable and solve them exactly without using the ansatz adopted in the
previous studies for SU(2) and SU(3). As a result, we obtain the general form
of the decomposition for SU(N) gauge link variables and confirm the previous
results obtained for SU(2) and SU(3).Comment: 16 page
BRST symmetry of SU(2) Yang-Mills theory in Cho--Faddeev--Niemi decomposition
We determine the nilpotent BRST and anti-BRST transformations for the
Cho--Faddeev-Niemi variables for the SU(2) Yang-Mills theory based on the new
interpretation given in the previous paper of the Cho--Faddeev-Niemi
decomposition. This gives a firm ground for performing the BRST quantization of
the Yang--Mills theory written in terms of the Cho--Faddeev-Niemi variables. We
propose also a modified version of the new Maximal Abelian gauge which could
play an important role in the reduction to the original Yang-Mills theory.Comment: 11 pages, no figure; Introduction improved, 3 references adde
Detection of spin voltaic effect in a p-n heterojunction
Model calculation and experimental data of
circularly-polarized-light-dependent photocurrent in a n-AlGaAs/p-InGaAs/p-GaAs
heterostructure are reported. It is found that, under the appropriate forward
bias condition, spin voltaic effect (SVE) can survive across the heterojunction
and give rise to detectable polarization-dependent photocurrent signals which
are greater than the signals due to the magnetic circular dichroism. Our
analysis suggests that SVE can be enhanced by optimization of layer thickness,
doping profile, and applied bias, making SVE favorable for the realization of a
semiconductor-based polarization detector, a spin-photodiode (spin-PD).Comment: 16 pages, 3figure
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