29,539 research outputs found
Associated Charmonium Production in p-pbar Annihilation
In this paper we summarize our recent results for low energy associated
charmonium production cross sections, using 1) crossing symmetry, and 2) an
explicit hadronic model. These predictions are of relevance to the planned
charmonium and charmonium hybrid production experiment PANDA at GSI.Comment: 5 pages, 5 figures. Contribution to the Second Meeting of the APS
Topical Group on Hadron Physics GHP2006. (Nashville, TN, 22-24 Oct. 2006
BB Intermeson Potentials in the Quark Model
In this paper we derive quark model results for scattering amplitudes and
equivalent low energy potentials for heavy meson pairs, in which each meson
contains a heavy quark. This "BB" system is an attractive theoretical
laboratory for the study of the nuclear force between color singlets; the
hadronic system is relatively simple, and there are lattice gauge theory (LGT)
results for V_BB(r) which may be compared to phenomenological models. We find
that the quark model potential (after lattice smearing) has qualitative
similarities to the LGT potential in the two B*B* channels in which direct
comparison is possible, although there is evidence of a difference in length
scales. The quark model prediction of equal magnitude but opposite sign for I=0
and I=1 potentials also appears similar to LGT results at intermediate r. There
may however be a discrepancy between the LGT and quark model I=1 BB potentials.
A numerical study of the two-meson Schrodinger equations in the (bqbar)(bqbar)
and (cqbar)(cqbar) sectors with the quark model potentials finds a single
"molecule", in the I=0 BB* sector. Binding in other channels might occur if the
quark model forces are augmented by pion exchange.Comment: 30 pages, 5 figures, revtex and epsfig. Submitted to Phys. Rev.
Hadronic Spectral Function and Charm Meson Production
At the chiral restoration/deconfinement transition, most hadrons undergo a
Mott transition from being bound states in the confined phase to resonances in
the deconfined phase. We investigate the consequences of this qualitative
change in the hadron spectrum on final state interactions of charmonium in hot
and dense matter, and show that the Mott effect for D-mesons leads to a
critical enhancement of the J/Psi dissociation rate. Anomalous J/Psi
suppression in the NA50 experiment is discussed as well as the role of the Mott
effect for the heavy flavor kinetics in future experiments at the LHC. The
status of our calculations of hadron-hadron cross sections using the quark
interchange and chiral Lagrangian approaches is reviewed, and an Ansatz for a
unification of these schemes is given.Comment: 12 pages, 6 figures, Proceedings of the Budapest'02 Workshop on Quark
& Hadron Dynamics, Budapest, Hungary, March 3-7, 200
Coulomb crystallization in expanding laser-cooled neutral plasmas
We present long-time simulations of expanding ultracold neutral plasmas,
including a full treatment of the strongly coupled ion dynamics. Thereby, the
relaxation dynamics of the expanding laser-cooled plasma is studied, taking
into account elastic as well as inelastic collisions. It is demonstrated that,
depending on the initial conditions, the ionic component of the plasma may
exhibit short-range order or even a superimposed long-range order resulting in
concentric ion shells. In contrast to ionic plasmas confined in traps, the
shell structures are built up from the center of the plasma cloud rather than
from the periphery
A New Experiment to Study Hyperon CP Violation and the Charmonium System
Fermilab operates the world's most intense antiproton source, now exclusively
dedicated to serving the needs of the Tevatron Collider. The anticipated 2009
shutdown of the Tevatron presents the opportunity for a world-leading low- and
medium-energy antiproton program. We summarize the status of the Fermilab
antiproton facility and review physics topics for which a future experiment
could make the world's best measurements.Comment: 16 pages, 3 figures, to appear in Proceedings of CTP symposium on
Supersymmetry at LHC: Theoretical and Experimental Perspectives, The British
University in Egypt, Cairo, Egypt, 11-14 March 200
Effective chiral-spin Hamiltonian for odd-numbered coupled Heisenberg chains
An system of odd number of coupled Heisenberg spin chains
is studied using a degenerate perturbation theory, where is the number of
coupled chains. An effective chain Hamiltonian is derived explicitly in terms
of two spin half degrees of freedom of a closed chain of sites, valid in
the regime the inter-chain coupling is stronger than the intra-chain coupling.
The spin gap has been calculated numerically using the effective Hamiltonian
for for a finite chain up to ten sites. It is suggested that the
ground state of the effective Hamiltonian is correlated, by examining
variational states for the effective chiral-spin chain Hamiltonian.Comment: 9 Pages, Latex, report ICTP-94-28
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