544 research outputs found
Coupled-channel effects in hadron-hadron correlation functions
Two-particle momentum correlation functions as measured in heavy ion
collisions or in high-energetic proton-proton collisions are studied. Special
emphasis is put on systems like or where effects from
the coupling to other channels could be relevant. In both cases other channels
open at relatively low momenta or are already open at the reaction threshold.
To have a solid basis, realistic coupled-channel interactions for
and
are utilized in the actual calculations. It is
found that the opening of the channel leaves a trace in the
correlation function that could be detectable in experiments.
Should the proposed -dibaryon be located close to or below the it
will have a very pronounced effect. The presence of open channels in systems
like or does influence the correlation functions significantly
at low momenta and will certainly complicate any dedicated analysis.Comment: 13 pages, 7 figures; table added, several comments adde
Strangeness S=-3 and -4 baryon-baryon interactions in chiral EFT
I report on recent progress in the description of baryon-baryon systems
within chiral effective field theory. In particular, I discuss results for the
strangeness S=-3 to -4 baryon-baryon systems, obtained to leading order.Comment: 4 pages, 2 figures, Contribution to the proceedings of the 12th
International Conference on Meson-Nucleon Physics and the Structure of the
Nucleon (MENU2010), May 31-June 4, 2010, College of William and Mary,
Williamsburg, Virgini
Scattering of charmed baryons on nucleons
Chiral effective field theory is utilized for extrapolating results on the
interaction, obtained in lattice QCD at unphysical (large) quark
masses, to the physical point. The pion-mass dependence of the components that
constitute the potential up to next-to-leading order
(pion-exchange diagrams and four-baryon contact terms) is fixed by information
from lattice QCD simulations. No recourse to SU(3) or SU(4) flavor symmetry is
made. It is found that the results of the HAL QCD Collaboration for quark
masses corresponding to -- MeV imply a moderately attractive
interaction at MeV with scattering lengths of
fm for the as well as the partial waves. For such
an interaction the existence of a charmed counterpart of the hypertriton is
unlikely but four- and/or five-baryons systems with a baryon could
be indeed bound.Comment: 7 pages, 2 figures; table added, several comments adde
Charm production in antiproton-proton annihilation
We study the production of charmed mesons (D) and baryons (Lambda_c) in
antiproton-proton (app) annihilation close to their respective production
thresholds. The elementary charm production process is described by either
baryon/meson exchange or by quark/gluon dynamics. Effects of the interactions
in the initial and final states are taken into account rigorously. The
calculations are performed in close analogy to our earlier study on app ->
antiLambda-Lambda and app -> antiK-K by connecting the processes via SU(4)
flavor symmetry. Our predictions for the antiLambda_c-Lambda_c production cross
section are in the order of 1 to 7 mb, i.e. a factor of around 10-70 smaller
than the corresponding cross sections for antiLambda-Lambda However, they are
100 to 1000 times larger than predictions of other model calculations in the
literature. On the other hand, the resulting cross sections for antiD-D
production are found to be in the order of 10^{-2} -- 10^{-1} microbarn and
they turned out to be comparable to those obtained in other studies.Comment: 5 pages, 2 figures, Contribution to the proceedings of the 21st
European Conference on Few-Body Problems in Physics, Salamanca, Spain, 30
August - 3 September 201
Production of charmed pseudoscalar mesons in antiproton-proton annihilation
We study the production of charmed mesons (D, D_s) in antiproton-proton
annihilation close to the reaction thresholds. The elementary charm production
process is described by baryon exchange and in the constituent quark model,
respectively. Effects of the interactions in the initial and final states are
taken into account rigorously. The calculations are performed in close analogy
to our earlier study on pbarp to KbarK by connecting the processes via SU(4)
flavor symmetry. Our predictions for the DDbar production cross section are in
the order of 10^{-2} -- 10^{-1} mu b. They turned out to be comparable to those
obtained in other studies. The cross section for a D_sD_s pair is found to be
of the same order of magnitude despite the fact that its production in pbarp
scattering requires a two-step process.Comment: 15 pages, 13 figures, some typos corrected, some comments adde
The (3770) resonance and its production in
The production of a meson-pair in antiproton-proton ()
annihilation close to the production threshold is investigated, with special
emphasis on the role played by the (3770) resonance. The study is
performed in a meson-baryon model where the elementary charm production process
is described by baryon exchange. Effects of the interactions in the initial and
final states are taken into account rigorously, where the latter involves also
those due to the (3770). The predictions for the production
cross section are in the range of 30 -- 250 nb, the contribution from the
(3770) resonance itself amounts to roughly 20 -- 80 nb.Comment: 6 pages, 6 figure
The reaction ppbar -> Lambda_c-Lambda_cbar close to threshold
Predictions for the charm-production reaction antiproton-proton ->
antiLambda_c-Lambda_c for energies near the threshold are presented. The
calculations are performed in a meson-exchange framework in close analogy to
our earlier study on antiproton-proton -> antiLambda-Lambda by connecting the
two processes via SU(4) symmetry. The obtained antiLambda_c-Lambda_c production
cross sections are in the order of 1 to 7 \mub, i.e. a factor of around 10
smaller than the corresponding cross sections for antiLambda-Lambda. However,
they are 100 to 1000 times larger than predictions of other model calculations
in the literature.Comment: 12 pages, 4 figure
Production of charmed baryons in collisions close to their thresholds
Cross sections for the charm-production reactions , , , and are presented, for energies near their respective thresholds. The
results are based on a calculation performed in the meson-exchange framework in
close analogy to earlier studies of the J\"ulich group on the
strangeness-production reactions , , by connecting the two sectors via SU(4) flavor
symmetry. The cross sections are found to be in the order of
at energies of MeV above the respective thresholds, for all considered
channels. Complementary to meson-exchange, where the charmed baryons are
produced by the exchange of and mesons, a charm-production potential
derived in a quark model is employed for assessing uncertainties. The cross
sections predicted within that picture turned out to be significantly smaller.Comment: 17 pages, 7 figure
Elastic pbar-d scattering and total pbar-d cross sections
Elastic pbar-d scattering is studied within the Glauber theory based on the
single- and double pbar-N scattering mechanisms. The full spin dependence of
the elementary pbar-N scattering amplitudes is taken into account and both the
S- and D-wave components of the deuteron are considered. The treatment of the
spin dependence is done in a (properly modified) formalism developed recently
by Platonova and Kukulin for the pd -> pd scattering process. Predictions for
differential cross sections and the spin observables A_y^d, A_y^pbar, A_xx,
A_yy are presented for antiproton beam energies between 50 and 300 MeV, using
amplitudes generated from the Nbar-N interaction model developed by the Juelich
group. Total polarized cross sections are calculated utilizing the optical
theorem. The efficiency of the polarization buildup for antiprotons in a
storage ring is investigated.Comment: 14 pages, 15 figures; some comments added, figure added, signs of
some spin-dependent cross sections correcte
The reactions p + n --> d + omega and p + n --> d + phi near threshold
The reactions p+n-->d+omega and p+n-->d+phi are studied within a relativistic
meson-exchange model of hadronic interactions. Predictions for the total cross
sections and for the angular distributions of the vector mesons are presented.
The resulting cross sections near threshold are around 10 - 30 microb for
p+n-->d+omega$ and 200 - 250 nb for p+n-->d+phi. A moderate deviation of the
cross section ratio sigma_{p+n-->d+phi} / sigma_{p+n-->d+omega} from that of
the Okubo-Zweig-Iizuka rule is predicted.Comment: 12 pages, 7 figure
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