22,157 research outputs found
Transverse Ward-Takahashi Identity, Anomaly and Schwinger-Dyson Equation
Based on the path integral formalism, we rederive and extend the transverse
Ward-Takahashi identities (which were first derived by Yasushi Takahashi) for
the vector and the axial vector currents and simultaneously discuss the
possible anomaly for them. Subsequently, we propose a new scheme for writing
down and solving the Schwinger-Dyson equation in which the the transverse
Ward-Takahashi identity together with the usual (longitudinal) Ward-Takahashi
identity are applied to specify the fermion-boson vertex function. Especially,
in two dimensional Abelian gauge theory, we show that this scheme leads to the
exact and closed Schwinger-Dyson equation for the fermion propagator in the
chiral limit (when the bare fermion mass is zero) and that the Schwinger-Dyson
equation can be exactly solved.Comment: 22 pages, latex, no figure
Detection of local-moment formation using the resonant interaction between coupled quantum wires
We study the influence of many-body interactions on the transport
characteristics of a novel device structure, consisting of a pair of quantum
wires that are coupled to each other by means of a quantum dot. Under
conditions where a local magnetic moment is formed in one of the wires, we show
that tunnel coupling to the other gives rise to an associated peak in its
density of states, which can be detected directly in a conductance measurement.
Our theory is therefore able to account for the key observations in the recent
study of T. Morimoto et al. [Appl. Phys. Lett. {\bf 82}, 3952 (2003)], and
demonstrates that coupled quantum wires may be used as a system for the
detection of local magnetic-moment formation
Compact lattice formulation of Cho-Faddeev-Niemi decomposition: string tension from magnetic monopoles
In this paper we begin on a new lattice formulation of the non-linear change
of variables called the Cho--Faddeev--Niemi decomposition in SU(2) Yang-Mills
theory. This is a compact lattice formulation improving the non-compact lattice
formulation proposed in our previous paper. Based on this formulation, we
propose a new gauge-invariant definition of the magnetic monopole current which
guarantees the magnetic charge quantization and reproduces the conventional
magnetic-current density obtained in the Abelian projection based on the
DeGrand--Toussaint method. Finally, we demonstrate the magnetic monopole
dominance in the string tension in SU(2) Yang-Mills theory on a lattice. Our
formulation enables one to reproduce in the gauge-invariant way remarkable
results obtained so far only in the Maximally Abelian gauge.Comment: 14 pages, v2: minor corrections; v3: explanations added and improve
Interacting with digital media at home via a second screen
In recent years Interactive Television (iTV) has become a household technology on a global scale. However, iTV is still a new technology in the early stages of its evolution.
Our previous research looked at how everyday users of iTV feel about the interactive part of iTV. In a series of studies we investigated how people use iTV services; their likes, dislikes, preferences and opinions. We then developed a second screen-based prototype device in response to these findings and tested it with iTV users in their own homes. This is a work in progress paper that outlines the work carried previously in the area of controlling interactive Television via a second screen. The positive user responses led us to extend the scope of our previous research to look into other related areas such as barriers to digital interactive media and personalisation of digital interactive media at home
Prediction of the capacitance lineshape in two-channel quantum dots
We propose a set-up to realize two-channel Kondo physics using quantum dots.
We discuss how the charge fluctuations on a small dot can be accessed by using
a system of two single electron transistors arranged in parallel. We derive a
microscopic Hamiltonian description of the set-up that allows us to make
connection with the two-channel Anderson model (of extended use in the context
of heavy-Fermion systems) and in turn make detailed predictions for the
differential capacitance of the dot. We find that its lineshape, which we
determined precisely, shows a robust behavior that should be experimentally
verifiable.Comment: 4 pages, 3 figure
KUV 01584-0939: A Helium-transferring Cataclysmic Variable with an Orbital Period of 10 Minutes
High speed photometry of KUV 01584-0939 (alias Cet3) shows that is has a
period of 620.26 s. Combined with its hydrogen-deficient spectrum, this implies
that it is an AM CVn star. The optical modulation is probably a superhump, in
which case the orbital period will be slightly shorter than what we have
observed.Comment: Published by PASP. See also the latest Early-Release Research Paper
website of the PAS
A formulation of the Yang-Mills theory as a deformation of a topological field theory based on background field method and quark confinement problem
By making use of the background field method, we derive a novel reformulation
of the Yang-Mills theory which was proposed recently by the author to derive
quark confinement in QCD. This reformulation identifies the Yang-Mills theory
with a deformation of a topological quantum field theory. The relevant
background is given by the topologically non-trivial field configuration,
especially, the topological soliton which can be identified with the magnetic
monopole current in four dimensions. We argue that the gauge fixing term
becomes dynamical and that the gluon mass generation takes place by a
spontaneous breakdown of the hidden supersymmetry caused by the dimensional
reduction. We also propose a numerical simulation to confirm the validity of
the scheme we have proposed. Finally we point out that the gauge fixing part
may have a geometric meaning from the viewpoint of global topology where the
magnetic monopole solution represents the critical point of a Morse function in
the space of field configurations.Comment: 45 pages, 3 figures included in LaTe
Renormalizing a BRST-invariant composite operator of mass dimension 2 in Yang-Mills theory
We discuss the renormalization of a BRST and anti-BRST invariant composite
operator of mass dimension 2 in Yang-Mills theory with the general BRST and
anti-BRST invariant gauge fixing term of the Lorentz type. The interest of this
study stems from a recent claim that the non-vanishing vacuum condensate of the
composite operator in question can be an origin of mass gap and quark
confinement in any manifestly covariant gauge, as proposed by one of the
authors. First, we obtain the renormalization group flow of the Yang-Mills
theory. Next, we show the multiplicative renormalizability of the composite
operator and that the BRST and anti-BRST invariance of the bare composite
operator is preserved under the renormalization. Third, we perform the operator
product expansion of the gluon and ghost propagators and obtain the Wilson
coefficient corresponding to the vacuum condensate of mass dimension 2.
Finally, we discuss the connection of this work with the previous works and
argue the physical implications of the obtained results.Comment: 49 pages, 35 eps-files, A number of typographic errors are corrected.
A paragraph is added in the beginning of section 5.3. Two equations (7.1) and
(7.2) are added. A version to be published in Phys. Rev.
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