3,067 research outputs found
\bar{p}p low energy parameters from annihilation cross section data
The recent experimental data obtained by the OBELIX group on total
annihilation cross section are analysed; the low energy spin averaged
parameters of the scattering amplitude (the imaginary parts of the
S-wave scattering length and P-wave scattering volume) are extracted from the
data. Their values are found to be equal to . The
results are in very good agreement with existing atomic data.Comment: latex.tar.gz file, 8 pages, 1 figur
Explicitly covariant light-front dynamics and some its applications
The light-front dynamics is an efficient approach to study of field theory
and of relativistic composite systems (nuclei at relativistic relative nucleon
momenta, hadrons in the quark models). The explicitly covariant version of this
approach is briefly reviewed and illustrated by some applications.Comment: 16 pages, 8 figures. Talk at the 21-st International Workshop on
Nuclear Theory, Rila Mountains, Bulgaria, June 10-15, 200
Deuteron electromagnetic form factors in the Light-Front Dynamics
The deuteron form factors are calculated in the framework of the relativistic
nucleon-meson dynamics, by means of the explicitly covariant light-front
approach. The inflluence of the nucleon electromagnetic form factors is
discussed.
At (GeV/c) the prediction for the structure function
and for the tensor polarization observable are in agreement with the
recent data of CEBAF/TJNAF.Comment: 1 latex.tar.gz file (18 pages, 8 figures in 11 .ps files) Submitted
for publicatio
Solutions of the Bethe-Salpeter equation in Minkowski space and applications to electromagnetic form factors
We present a new method for solving the two-body Bethe-Salpeter equation in
Minkowski space. It is based on the Nakanishi integral representation of the
Bethe-Salpeter amplitude and on subsequent projection of the equation on the
light-front plane. The method is valid for any kernel given by the irreducible
Feynman graphs and for systems of spinless particles or fermions. The
Bethe-Salpeter amplitudes in Minkowski space are obtained. The electromagnetic
form factors are computed and compared to the Euclidean results.Comment: 20 pages, 14 figures, contribution to proceedings of the workshop:
"Relativistic Description of Two- and Three-Body Systems in Nuclear Physics",
ECT*, October 19-23, 2009. To be published in Few-Body System
Solution of the Bethe-Salpeter equation in Minkowski space for a two fermion system
The method of solving the Bethe-Salpeter equation in Minkowski space,
developed previously for spinless particles, is extended to a system of two
fermions. The method is based on the Nakanishi integral representation of the
amplitude and on projecting the equation on the light-front plane. The
singularities in the projected two-fermion kernel are regularized without
modifying the original BS amplitudes. The numerical solutions for the J=0 bound
state with the scalar, pseudoscalar and massless vector exchange kernels are
found. Binding energies are in close agreement with the Euclidean results.
Corresponding amplitudes in Minkowski space are obtained.Comment: 8 pages, 5 figures. Contribution to the proceedings of the Workshop:
Light-Cone 2010, "Relativistic Hadronic and Particle Physics", June 14-18,
2010, Valencia, Spain. To be published in the online journal "Proceedings of
Science" - Po
Critical stability of three-body relativistic bound states with zero-range interaction
For zero-range interaction providing a given mass M_2 of the two-body bound
state, the mass M_3 of the relativistic three-body bound state is calculated.
We have found that the three-body system exists only when M_2 is greater than a
critical value M_c (approx. 1.43m for bosons and approx. 1.35m for fermions, m
is the constituent mass). For M_2=M_c the mass M_3 turns into zero and for
M_2<M_c there is no solution with real value of M_3.Comment: 6 pages, 3 figures. Contribution to the workshop "Critical
Stability-III", 1-6 Sept. 2003, Trento, Italy. To be published in "Few-Body
Systems
Front-form calculation of the deuteron EM form factors
The deuteron form factors are calculated in the framework of the relativistic
nucleon-meson dynamics. The relativistic effects change considerably the S- and
D-waves of the deuteron, result in the dominating extra component in the
deuteron wave function and generate the contact interaction between the
nucleon, mesons and photon. The prediction for the polarization observable
is in good agreement with the recent data of TJNAF/CEBAF.Comment: 4 pages, 1 figure. Contribution to the XVI European Conference on
Few-Body problems in Physics, Autrans june 1998. To appear in Few-Body
Systems Suppl. Latex.tar.gz fil
Zero energy scattering calculation in Euclidean space
We show that the Bethe-Salpeter equation for the scattering amplitude in the
limit of zero incident energy can be transformed into a purely Euclidean form,
as it is the case for the bound states. The decoupling between Euclidean and
Minkowski amplitudes is only possible for zero energy scattering observables
and allows determining the scattering length from the Euclidean Bethe-Salpeter
amplitude. Such a possibility strongly simplifies the numerical solution of the
Bethe-Salpeter equation and suggests an alternative way to compute the
scattering length in Lattice Euclidean calculations without using the Luscher
formalism. The derivations contained in this work were performed for scalar
particles and one-boson exchange kernel. They can be generalized to the fermion
case and more involved interactions.Comment: 11 pages, 3 figures, to be published in Phys. Lett.
- âŠ