Coronal global EIT waves as tools for multiple diagnostics

Observations in EUV lines of the solar corona revealed large scale propagating waves generated by eruptive events able to travel across the solar disk for large distances. In the low corona, CMEs are known to generate, e.g. EIT waves which can be used to sample the coronal local and global magnetic field. This contribution presents theoretical models for finding values of magnetic field in the quiet Sun and coronal loops based on the interaction of global waves and local coronal loops as well as results on the generation and propagation of EIT waves. The physical connection between local and global solar coronal events (e.g. flares, EIT waves and coronal loop oscillations) will also be explored

Heavy Hadrons and QCD Instantons

Heavy hadrons are analyzed in a random and dilute gas of instantons. We derive the instanton-induced interactions between heavy and light quarks at next to leading order in the heavy quark mass and in the planar approximation, and discuss their effects on the hadronic spectrum. The role of these interactions in the formation of exotic hadrons is also discussed.Comment: 26 pages, REVTeX, 2 tables, 5 figures, uses FEYNMAN.st

Scattering Through QCD Sphalerons

Diffractive parton-parton scattering in the soft pomeron regime can be explained by the production of a QCD sphaleron. Sphaleron production results into the emission of $3+2N_F$ gluons and quarks. At RHIC we expect many sphalerons to be released thereby affecting most prompt processes.Comment: Contribution to quark matter 200

Diameters, distortion and eigenvalues

We study the relation between the diameter, the first positive eigenvalue of the discrete $p$-Laplacian and the $\ell_p$-distortion of a finite graph. We prove an inequality relating these three quantities and apply it to families of Cayley and Schreier graphs. We also show that the $\ell_p$-distortion of Pascal graphs, approximating the Sierpinski gasket, is bounded, which allows to obtain estimates for the convergence to zero of the spectral gap as an application of the main result.Comment: Final version, to appear in the European Journal of Combinatoric

Nonabelian Berry Phases in Baryons

We show how generic nonabelian gauge fields can be induced in baryons when a hierarchy of fast degrees of freedom is integrated out. We identify them with nonabelian Berry potentials and discuss their role in transmuting quantum numbers in bag and soliton models of baryons. The resulting baryonic spectra for both light and heavy quark systems are generic and resemble closely the excitation spectrum of diatomic molecules. The symmetry restoration in the system, i.e., the electronic rotational invariance in diatomic molecules, the heavy-quark symmetry in heavy baryons etc. is interpreted in terms of the vanishing of nonabelian Berry potentials that otherwise govern the hyperfine splitting.Comment: Latex 35 pages (2 figures not added, will be faxed if requested), NTG-92-2

QCD Instantons in Vacuum and Matter

The singlet coupling to the topological charge density in the instanton vacuum, causes the instantons and antiinstantons to be screened over distances of the order of 1/2 fm. Dilute instanton systems behave as a free gas, while dense instanton systems behave as a plasma. The free gas behaviour is favored by a density of 1 fm$^{-4}$. Owing to the Higgs mechanism, the $\eta$' mass is heavy (1100 MeV). The vacuum topological susceptibility is small (0.07 fm$^{-4}$) and consistent with the QCD Ward identity. In the chiral limit, the singlet screening vanishes, leading to a four dimensional plasma state with a temperature given by the nonet decay constant $f$ (90 MeV). The phase is Debye screened. In the presence of matter, the screening is quenched, and a Kosterlitz-Thouless transition may occur signaling the restoration of the $U_A(1)$ symmetry. We suggest to use the spatial asymptotics of the static topological charge correlator together with the topological susceptibility to probe the interplay between the $U_A(1)$ restoration and the chiral restoration in finite temperature QCD. The relevance of these results to the bulk thermodynamics in the instanton vacuum is discussed.Comment: 18 Page