No Arabic abstract
Partial decay widths of various decay channels of the X(1835) are evaluated in the 3P0 quark model, assuming that the X(1835) is a nucleon-antinucleon bound state. It is found that the decays to rho+rho, omega+omega and pion+a0(1450) dominate over other channels, and that the product branching fractions of J/psi to pion+pion+eta and J/psi to pion+pion+eta are in the same order. We suggest that the X(1835) may be searched in the pion+a0(1450) channel.
In the past, several efficient methods have been developed to solve the Schroedinger equation for four-nucleon bound states accurately. These are the Faddeev-Yakubovsky, the coupled-rearrangement-channel Gaussian-basis variational, the stochastic variational, the hyperspherical variational, the Greens function Monte Carlo, the no-core shell model and the effective interaction hyperspherical harmonic methods. In this article we compare the energy eigenvalue results and some wave function properties using the realistic AV8 NN interaction. The results of all schemes agree very well showing the high accuracy of our present ability to calculate the four-nucleon bound state.
Recently a formalism for a direct treatment of the Faddeev equation for the three-nucleon bound state in three dimensions has been proposed. It relies on an operator representation of the Faddeev component in the momentum space and leads to a finite set of coupled equations for scalar functions which depend only on three variables. In this paper we provide further elements of this formalism and show the first numerical results for chiral NNLO nuclear forces.
We study the partial decay widths of the charmonium states ($J/psi$, $psi(3686)$, $psi(3770)$, $chi_{c0}$, $chi_{c2}$) to $Dbar D$ ($D^+D^-$ or $D^0bar {D^0}$) in isospin asymmetric nuclear matter, in the presence of strong magnetic fields. The in-medium partial decay widths of charmonium states to $Dbar D$ are calculated within a light quark--antiquark pair creation model, namely the $^3P_0$ model, using the in--medium masses of the charmonia as well as $D$ and $bar D$ mesons in the magnetized nuclear matter obtained within a chiral effective model. The presence of a magnetic field leads to Landau quantization of the energy levels of the proton in the nuclear medium. The effects of magnetic field and isospin asymmetry on the charmonium decay widths to $Dbar D$ are found to be quite prominent. The effects of the anomalous magnetic moments have also been taken into consideration for obtaining the in-medium masses of these heavy flavour mesons, used to calculate the partial decay widths of the charmonium states. The medium modifications of the charmonium decay widths can have observable consequences on the production of the charmed mesons in high energy asymmetric heavy ion collision experiments.
This report is a historical review of the salient results in low energy antiproton-proton and antineutron-proton annihilation obtained at the Low Energy Antiproton Ring (LEAR), which was operated at CERN between 1983 and 1996. The intention is to provide guidelines for future experiments at the CERN AD/ELENA complex and elsewhere. In the spirit of this workshop, hadron spectroscopy - one of the cornerstones at LEAR - is briefly mentioned, while emphasis is put on the annihilation mechanism on one and two nucleons, the final state multiplicity distributions and the contributions from quarks, in particular in annihilation channels involving strangeness.
The in-medium partial decay widths of $Upsilon (4S) rightarrow Bbar B$ in magnetized asymmetric nuclear matter are studied using a field theoretic model for composite hadrons with quark/antiquark constituents. The medium modifications of the decay widths of $Upsilon (4S)$ to $Bbar B$ pair in magnetized matter, arise due to the mass modifications of the decaying $Upsilon (4S)$ as well as of the produced $B$ and $bar B$ mesons. The effects of the anomalous magnetic moments for the proton and neutron are taken into consideration in the present investigation. The presence of the external magnetic field is observed to lead to different mass modifications within the $B (B^+, B^0)$ as well as the $bar B (B^-, bar {B^0})$ doublets, even in isospin symmetric nuclear matter, due to the difference in the interactions of the proton and the neutron to the electromagnetic field. This leads to difference in the upsilon decay widths to the neutral ($B^0 bar {B^0}$) and the charged ($B^+ B^-$) pairs in the magnetized symmetric nuclear matter. The isospin asymmetry is observed to lead to quite different behaviours for the $Upsilon (4S)$ decay widths to the charged and neutral $Bbar B$. In the presence of the magnetic field, the Landau level contributions give rise to positive shifts in the masses of the charged $B$ and $bar B$ mesons. This leads to the decay of $Upsilon(4S)$ to the charged $B^+ B^-$ to be suppressed as compared to the neutral $Bbar B$ pair, especially at low densities. This may lead to suppression in the production of the charged $B^pm$ mesons as compared to the neutral $B^0$ and $bar {B^0}$ mesons at LHC and RHIC.