5,855 research outputs found
The Electromagnetic Gauge Field Interpolation between the Instant Form and the Front Form of the Hamiltonian Dynamics
We present the electromagnetic gauge field interpolation between the instant
form and the front form of the relativistic Hamiltonian dynamics and extend our
interpolation of the scattering amplitude presented in the simple scalar field
theory to the case of the electromagnetic gauge field theory with the scalar
fermion fields known as the sQED theory. We find that the Coulomb gauge in the
instant form dynamics (IFD) and the light-front gauge in the front form
dynamics, or the light-front dynamics (LFD), are naturally linked by the
unified general physical gauge that interpolates between these two forms of
dynamics and derive the spin-1 polarization vector for the photon that can be
generally applicable for any interpolation angle. Corresponding photon
propagator for an arbitrary interpolation angle is found and examined in terms
of the gauge field polarization and the interpolating time ordering. Using
these results, we calculate the lowest-order scattering processes for an
arbitrary interpolation angle in sQED. We provide an example of breaking the
reflection symmetry under the longitudinal boost, ,
for the time-ordered scattering amplitude in any interpolating dynamics except
the LFD and clarify the confusion in the prevailing notion of the equivalence
between the infinite momentum frame (IMF) and the LFD. The particular
correlation found in our previous analysis of the scattering amplitude in the
simple scalar field theory, coined as the J-shaped correlation, between the
total momentum of the system and the interpolation angle persists in the
present analysis of the sQED scattering amplitude. We discuss the singular
behavior of this correlation in conjunction with the zero-mode issue in the
LFD.Comment: 22 pages, 5 figure
Charmonium ground and excited states at finite temperature from complex Borel sum rules
Charmonium spectral functions in vector and pseudoscalar channels at finite
temperature are investigated through the complex Borel sum rules and the
maximum entropy method. Our approach enables us to extract the peaks
corresponding to the excited charmonia, and , as
well as those of the ground states, and , which has never been
achieved in usual QCD sum rule analyses. We show the spectral functions in
vacuum and their thermal modification around the critical temperature, which
leads to the almost simultaneous melting (or peak disappearance) of the ground
and excited states.Comment: 6 pages, 4 figures; published versio
Pauli-Villars Regularization Elucidated in Bopp-Podolsky's Generalized Electrodynamics
We discuss an inherent Pauli-Villars regularization in Bopp-Podolsky's
generalized electrodynamics. Introducing gauge-fixing terms for Bopp-Podolsky's
generalized electrodynamic action, we realize a unique feature for the
corresponding photon propagator with a built-in Pauli-Villars regularization
independent of the gauge choice made in Maxwell's usual electromagnetism.
According to our realization, the length dimensional parameter associated
with Bopp-Podolsky's higher order derivatives corresponds to the inverse of the
Pauli-Villars regularization mass scale , i.e. .
Solving explicitly the classical static Bopp-Podolsky's equations of motion for
a specific charge distribution, we explore the physical meaning of the
parameter in terms of the size of the charge distribution. As an offspring
of the generalized photon propagator analysis, we also discuss our findings
regarding on the issue of the two-term vs. three-term photon propagator in
light-front dynamics
Linking generalized parton distributions to constituent quark models
The link between the nucleon generalized parton distributions and the
non-diagonal one-body density matrix in momentum space is studied. Attention is
focussed on the region where quark generalized parton distributions (GPD's)
describe emission and reabsorption of a single active quark by the target
nucleon. The correct covariant connection with wave functions used in any
constituent quark model is established. Results obtained with different
constituent quark models are presented for the unpolarized quark GPD's.Comment: 2 new figures included and references added, conclusions unchanged.
Version to appear in Nucl. Phys.
Stand structure and dynamics during a 16-year period in a sub-boreal conifer-hardwood mixed forest, northern Japan
ArticleFOREST ECOLOGY AND MANAGEMENT. 174(1-3):39-50(2003)journal articl
A New Epoxy-cadinane Sesquiterpene from the Marine Brown Alga Dictyopteris divaricata
A new epoxy-cadinane sesquiterpene, 4β,5β-epoxycadinan-1β-ol (1), and six known cadinane sesquiterpenes: cadinan-1,4,5-triol (2), 4α,5β-dihydroxycubenol (3), cubenol (4), cadinan-3-ene-1,5-diol (5), cubenol-3-one (6), and torreyol (7), were isolated from a sample of marine brown alga Dictyopteris divaricata collected off the coast of Yantai (China). Their structures were established by detailed MS and NMR spectroscopic analysis, as well as comparison with literature data
Chiral-odd transversity spin structure function of the nucleon in a constituent quark model
We study the chiral-odd transversity spin-dependent quark distribution
function of the nucleon in a constituent quark model. The twist-2
structure functions, , and are calculated within the
diquark spectator approximation. Whereas an inequality holds with the interaction between quark and diquark being scalar, the
axial-vector effective quark-diquark interaction, which contributes to the
-quark distribution, does not lead to such a simple relation. We find that
for the -quark becomes somewhat smaller than , when we
fix the model parameter to reproduce known other structure functions. We also
include corrections due to the non-trivial structure of the constituent quark,
which is modeled by the Goldstone boson dressing. This improves agreements of
and with experiments, and brings further reduction of
distribution. Consequences for semi-inclusive experiments are also
discussed.Comment: 33 pages, latex with 13 figures, to appear in Nuclear Physics A,
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