132 research outputs found
Comment on `Glueball spectrum from a potential model'
In a recent article, W.-S. Hou and G.-G. Wong [Phys. Rev. D {\bf 67}, 034003
(2003)] have investigated the spectrum of two-gluon glueballs below 3 GeV in a
potential model with a dynamical gluon mass. We point out that, among the 18
states calculated by the authors, only three are physical. The other states
either are spurious or possess a finite mass only due to an arbitrary
restriction of the variational parameter.Comment: Comment on pape
- Glueball Spectrum within a Constituent Picture
The quantum numbers and mass hierarchy of the glueballs observed in
-dimensional lattice QCD with gauge group SU() are shown to be in
agreement with a constituent picture. The agreement is maintained when going
from glueballs to gluelumps, and when the gauge group SO() is taken
instead of SU()
Mass formula for strange baryons in large QCD versus quark model
A previous work establishing a connection between a quark model, with
relativistic kinematics and a -confinement plus one gluon exchange, and the
expansion mass formula is extended to strange baryons. Both methods
predict values for the SU(3)-breaking mass terms which are in good agreement
with each other. Strange and nonstrange baryons are shown to exhibit Regge
trajectories with an equal slope, but with an intercept depending on the
strangeness. Both approaches agree on the value of the slope and of the
intercept and on the existence of a single good quantum number labeling the
baryons within a given Regge trajectory.Comment: 2 figure
Observer with a constant proper acceleration
Relying on the equivalence principle, a first approach of the general theory
of relativity is presented using the spacetime metric of an observer with a
constant proper acceleration. Within this non inertial frame, the equation of
motion of a freely moving object is studied and the equation of motion of a
second accelerated observer with the same proper acceleration is examined. A
comparison of the metric of the accelerated observer with the metric due to a
gravitational field is also performed.Comment: 5 figure
String deformations induced by retardation effects
The rotating string model is an effective model of mesons, in which the quark
and the antiquark are linked by a straight string. We previously developed a
new framework to include the retardation effects in the rotating string model,
but the string was still kept straight. We now go a step further and show that
the retardation effects cause a small deviation of the string from the straight
line. We first give general arguments constraining the string shape. Then, we
find analytical and numerical solutions for the string deformation induced by
retardation effects. We finally discuss the influence of the curved string on
the energy spectrum of the model.Comment: 3 figure
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