35,574 research outputs found
The Synthesis, Resolution and Configuration of Beta-hydroxyvaline
Synthesis, resolution, and configuration of alpha-hydroxyvalin
Role of high-spin hyperon resonances in the reaction of
The recent data taken by the CLAS Collaboration at the Thomas Jefferson
National Accelerator Facility for the reaction of
are reanalyzed within a relativistic meson-exchange model of hadronic
interactions. The present model is an extension of the one developed in an
earlier work by Nakayama, Oh, and Haberzettl [Phys. Rev. C 74, 035205 (2006)].
In particular, the role of the spin-5/2 and -7/2 hyperon resonances, which were
not included in the previous model, is investigated in the present study. It is
shown that the contribution of the hyperon having spin-7/2 and
positive parity has a key role to bring the model predictions into a fair
agreement with the measured data for the invariant mass
distribution.Comment: 8 pages, 3 figures, REVTe
Einstein Manifolds As Yang-Mills Instantons
It is well-known that Einstein gravity can be formulated as a gauge theory of
Lorentz group where spin connections play a role of gauge fields and Riemann
curvature tensors correspond to their field strengths. One can then pose an
interesting question: What is the Einstein equations from the gauge theory
point of view? Or equivalently, what is the gauge theory object corresponding
to Einstein manifolds? We show that the Einstein equations in four dimensions
are precisely self-duality equations in Yang-Mills gauge theory and so Einstein
manifolds correspond to Yang-Mills instantons in SO(4) = SU(2)_L x SU(2)_R
gauge theory. Specifically, we prove that any Einstein manifold with or without
a cosmological constant always arises as the sum of SU(2)_L instantons and
SU(2)_R anti-instantons. This result explains why an Einstein manifold must be
stable because two kinds of instantons belong to different gauge groups,
instantons in SU(2)_L and anti-instantons in SU(2)_R, and so they cannot decay
into a vacuum. We further illuminate the stability of Einstein manifolds by
showing that they carry nontrivial topological invariants.Comment: v4; 17 pages, published version in Mod. Phys. Lett.
Higgs bosons of a supersymmetric model at the Large Hadron Collider
It is found that CP symmetry may be explicitly broken in the Higgs sector of
a supersymmetric model with two extra neutral gauge bosons at the
one-loop level. The phenomenology of the model, the Higgs sector in particular,
is studied for a reasonable parameter space of the model, in the presence of
explicit CP violation at the one-loop level. At least one of the neutral Higgs
bosons of the model might be produced via the fusion process at the Large
Hadron Collider.Comment: 23 pages, 5 figures, JHE
On the sign of the pi-rho-omega coupling constant
It is shown that the relative sign between the and
coupling constants can be determined most sensitively from production
processes in collisions. Recent data on these reactions clearly favor the
sign of the coupling constant which is opposite to that
inferred from studies of the photoproduction reaction in combination with the
vector meson dominance assumption and used by many authors. Implication of this
finding in the description of other reactions is discussed.Comment: 6 pages, 4 figures, REVTeX, to be published in Phys. Lett.
Photoproduction of Xi off nucleons
The photoproduction reaction is investigated based on
a relativistic meson-exchange model of hadronic interactions. The production
amplitude is calculated in the tree-level approximation from relevant effective
Lagrangians, whose (coupling constant) parameters are mostly fixed from the
empirical data and/or quark models together with SU(3) symmetry considerations.
Gauge invariance of the resulting amplitude is maintained by introducing the
contact currents by extending the gauge-invariant approach of Haberzettl for
one-meson photoproduction to two-meson photoproduction. The role of the
intermediate low-lying hyperons and of the intermediate higher-mass hyperon
resonances are analyzed in detail. In particular, the basic features of the
production of in and their possible
manifestations in the forthcoming experimental data are discussed.Comment: 18 pages, 17 figures, REVTeX, 1 figure added, to appear in Phys. Rev.
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