13 research outputs found
Near-Maximal Mixing of Scalar Gluonium and Quark Mesons: A Gaussian Sum-Rule Analysis
Gaussian QCD sum-rules are ideally suited to the study of mixed states of
gluonium (glueballs) and quark () mesons because of their capability
to resolve widely-separated states of comparable strength. The analysis of the
Gaussian QCD sum-rules (GSRs) for all possible two-point correlation functions
of gluonic and non-strange () quark scalar () currents is
discussed. For the non-diagonal sum-rule of gluonic and currents we
show that perturbative and gluon condensate contributions are chirally
suppressed compared to non-perturbative effects of the quark condensate, mixed
condensate, and instantons, implying that the mixing of quark mesons and
gluonium is of non-perturbative origin. The independent predictions of the
masses and relative coupling strengths from the non-diagonal and the two
diagonal GSRs are remarkably consistent with a scenario of two states with
masses of approximately 1 GeV and 1.4 GeV that couple to significant mixtures
of quark and gluonic currents. The mixing is nearly maximal with the heavier
mixed state having a slightly larger coupling to gluonic currents than the
lighter state.Comment: Updated version contains extended analysis and revised analysis
methods. 21 pages, 14 figure
Modeling of Venus, Mars, and Titan
International audienceIncreased computer capacity has made it possible to model the global plasma and neutral dynamics near Venus, Mars and Saturn's moon Titan. The plasma interactions at Venus, Mars, and Titan are similar because each possess a substantial atmosphere but lacks a global internally generated magnetic field. In this article three self-consistent plasma models are described: the magnetohydrodynamic (MHD) model, the hybrid model and the fully kinetic plasma model. Chamberlain and Monte Carlo models of the Martian exosphere are also described. In particular, we describe the pros and cons of each model approach. Results from simulations are presented to demonstrate the ability of the models to capture the known plasma and neutral dynamics near the three objects