21,515 research outputs found
Structure of heavy baryons in a pion mean-field approach
In this talk, we briefly review a series of recent works on singly heavy
baryons, based on a pion mean-field approach. In the limit of the infinitely
heavy quark mass, heavy baryons are governed mainly by the light degress of
freedom. Taking the number of colors to be infinity, a heavy baryon arises as a
state consisting of valence quarks bound by the pion mean fields
created self-consistently. Within this framework, we present the results of the
mass spectra of the charmed and bottom baryons, and their magnetic moments. The
behavior of the electromagnetic form factors will be also mentioned.Comment: 4 pages, No figure. Contribution to the proceedings of "8th
International Conference on Quarks and Nuclear Physics (QNP2018)", November
13-17, 2018, Tsukuba, Japa
Remark on the Limit Case of Positive Mass Theorem for Manifolds with Inner Boundary
In [5] Herzlich proved a new positive mass theorem for Riemannian 3-manifolds
whose mean curvature of the boundary allows some positivity. In this
paper we study what happens to the limit case of the theorem when, at a point
of the boundary, the smallest positive eigenvalue of the Dirac operator of the
boundary is strictly larger than one-half of the mean curvature (in this case
the mass must be strictly positive). We prove that the mass is bounded
from below by a positive constant , and the equality
holds only if, outside a compact set, is conformally
flat and the scalar curvature vanishes. The constant is uniquely
determined by the metric via a Dirac-harmonic spinor.Comment: 12 pages, latex2
Photoproduction with Nucleon Resonances
We investigate the reaction mechanism of photoproduction off
the neutron target, i.e., , in the range of GeV. We employ an effective Lagrangian method at the tree-level Born
approximation combining with a Regge approach. As a background, the
-Reggeon trajectory is taken into account in the channel and
and hyperons in the -channel Feynman diagram. In addition, the role
of various nucleon resonances listed in the Particle Data Group (PDG) is
carefully scrutinized in the channel where the resonance parameters are
extracted from the experimental data and constituent quark model. We present
our numerical results of the total and differential cross sections and compare
them with the recent CLAS data. The effect of the narrow nucleon resonance
on cross sections is studied in detail and it turns out that
its existence is essential in photoproduction to reproduce the
CLAS data.Comment: 4 pages, 3 figures, Proceedings of "8th International Conference on
Quarks and Nuclear Physics (QNP2018)", November 13-17, 2018, Tsukuba, Japa
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