1,245 research outputs found
Masses and widths of scalar-isoscalar multi-channel resonances from data analysis
Peculiarities of obtaining parameters for broad multi-channel resonances from
data are discussed analyzing the experimental data on processes
in the channel in a
model-independent approach based on analyticity and unitarity and using an
uniformization procedure. We show that it is possible to obtain a good
description of the scattering data from the threshold to 1.89 GeV with
parameters of resonances cited in the PDG tables as preferred. However, in this
case, first, representation of the background is unsatisfactory;
second, the data on the coupled process are not well
described even qualitatively above 1.15 GeV when using the resonance parameters
from the only scattering analysis. The combined analysis of these
coupled processes is needed, which is carried out satisfactorily. Then both
above-indicated flaws, related to the analysis of solely the
-scattering, are cured. The most remarkable change of parameters with
respect to the values of only scattering analysis appears for the mass
of the which is now in some accordance with the Weinberg prediction
on the basis of mended symmetry and with an analysis using the large-
consistency conditions between the unitarization and resonance saturation. The
obtained -scattering length in case when we restrict to the
analysis of the scattering or consider so-called A-solution (with a
lower mass and width of meson) agrees well with prediction of chiral
perturbation theory (ChPT) and with data extracted at CERN by the NA48/2
Collaboration from the analysis of the decay and by the DIRAC
Collaboration from the measurement of the lifetime.Comment: 21 pages, 3 figures, 6 table
Electromagnetic form factor via Bethe-Salpeter amplitude in Minkowski space
For a relativistic system of two scalar particles, we find the Bethe-Salpeter
amplitude in Minkowski space and use it to compute the electromagnetic form
factor. The comparison with Euclidean space calculation shows that the Wick
rotation in the form factor integral induces errors which increase with the
momentum transfer Q^2. At JLab domain (Q^2=10 GeV^2/c^2), they are about 30%.
Static approximation results in an additional and more significant error. On
the contrary, the form factor calculated in light-front dynamics is almost
indistinguishable from the Minkowski space one.Comment: 8 pages, 7 figures, to be published in Eur. Phys. J. A; Reference
[15] is adde
The Red Queen visits Minkowski Space
When Alice went `Through the Looking Glass' [1], she found herself in a
situation where she had to run as fast as she could in order to stay still. In
accordance with the dictum that truth is stranger than fiction, we will see
that it is possible to find a situation in special relativity where running
towards one's target is actually counter-productive. Although the situation is
easily analysed algebraically, the qualitative properties of the analysis are
greatly illuminated by the use of space-time diagrams
Stable quark stars beyond neutran stars : can they account for the missing matter ?
The structure of a spherically symmetric stable dark 'star' is discussed, at
zero temperature, containing 1) a core of quarks in the deconfined phase and
antileptons 2) a shell of hadrons in particular , , and
and leptons or antileptons and 3) a shell of hydrogen in the
superfluid phase. If the superfluid hydrogen phase goes over into the
electromagnetic plasma phase at densities well below one atom / ,
as is usually assumed, the hydrogen shell is insignificant for the mass and the
radius of the 'star'. These quantities are then determined approximatively :
mass = 1.8 solar masses and radius = 9.2 km. On the contrary if densities of
the order of one atom / do form a stable hydrogen superfluid
phase, we find a large range of possible masses from 1.8 to 375 solar masses.
The radii vary accordingly from 9 to 1200 km.Comment: 5 pages, 2 figures, contribution to Strange Quark Matter conference,
Frankfurt, Germany, Sept. 200
The Field Theory of Gravitation and The Rest Mass of Particles
It is shown in this work that all free physical fields should have a nonzero
rest mass according to the field theory of gravitation.Comment: 4 page
Glueball Masses in Relativistic Potential Model
The problem of glueball mass spectra using the relativistic Dirac equation is
studied. Also the Breit-Fermi approach used to obtaining hyperfine splitting in
glueballs. Our approach is based on the assumption, that the nature and the
forces between two gluons are the short-range. We were to calculate the
glueball masses with used screened potential.Comment: 7 pages, LaTe
Hadronic structure aspects of decays
As is known from previous studies the lepton number violating decays have good prospects to probe new physics beyond the
Standard Model and provide valuable information on neutrino masses and mixing.
We analyze these processes with an emphasis on their hadronic structure
aspects applying relativistic constituent quark model. We conclude that the
previously ignored contribution associated with the t-channel Majorana neutrino
exchange is comparable with the s-channel one in a wide range of neutrino
masses. We also estimated model independent absolute upper bounds on neutrino
contribution to these decays.Comment: 15 pages, 1 figure. Version to appear in PRD, normalization factor in
Eq. (25) is correcte
Discreteness of the volume of space from Bohr-Sommerfeld quantization
A major challenge for any theory of quantum gravity is to quantize general
relativity while retaining some part of its geometrical character. We present
new evidence for the idea that this can be achieved by directly quantizing
space itself. We compute the Bohr-Sommerfeld volume spectrum of a tetrahedron
and show that it reproduces the quantization of a grain of space found in loop
gravity.Comment: 4 pages, 4 figures; v2, to appear in PR
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