H. Arthur Weldon

Structure of the quark propagator at high temperatures

In the high temperature, chirally invariant phase of QCD, the quark propagator is shown to have two sets of poles with different dispersion relations. A reflection property in momentum space relates all derivatives at zero-momentum of the particle and hole energies, the particle and hole damping rates, and the particle and hole residues. No use is made of perturbation theory.

Particles and holes

A neutral plasma at very high temperature(T ⪢ m) is shown to have a partially full Fermi sea. The removal of a fermion from this sea leaves a fermionic hole excitation whose additive quantum numbers are the negatives of the missing fermion. Particles and holes with the same chirality are shown to have the opposite helicity. The dispersion relation for both particles and holes is calculated to one-loop order and possible phenomenonnlogical consequences are discussed.

Dilepton enhancement at 2mπ and chiral symmetry restoration

Abstract In vacuum the isosinglet J PC =0 ++ sigma meson has a very large decay to π + π − (because of phase space) and a very small decay to e + e − (because two photons and reqired by CP invariance). In hadronic matter at high temperature and/or density the situation is reversed. The smaller value of m σ reduces the phase space for σ → π + π − , which suppresses the hadronic rate; the CP -violating media allows the sigma to decay to lepton pairs by one photon, which increases the leptonic rate. The result is an enhancement in the e + e − invariant mass near 2 m π that signals chiral symmetry restoration.

Fermions without vierbeins in curved space-time

A general formulation of spinor fields in Riemannian space-time is given without using vierbeins. The space-time dependence of the Dirac matrices required by the anticommutation relation {\gamma_{\mu},\gamma_{\nu}}=2g_{\mu\nu} determines the spin connection. The action is invariant under any local spin base transformations in the 32 parameter group Gl(4,c) and not just under local Lorentz transformations. The Dirac equation and the energy-momentum tensor are computed from the action.

Structure of the Gluon Propagator at Finite Temperature

The background gauge renormalization of the first order formulation of the Yang-Mills theory is studied by means of the BRST identities. Despite the fact that certain improper diagrams which violate the BRST symmetry must be removed, the renormalizability may be indirectly deduced to all orders. This method involves rescalings and mixings of the fields, which lead to a renormalized effective action for the background field theory.

Thermal field theory and generalized light front quantization

The dependence of thermal field theory on the surface of quantization and on the velocity of the heat bath is investigated by working in general coordinates that are arbitrary linear combinations of the Minkowski coordinates. In the general coordinates the metric tensor

Suppression of bremsstrahlung at nonzero temperature

g_{\bar{\mu\nu}}

Thermal self-energies using light-front quantization

is non-diagonal. The Kubo, Martin, Schwinger condition requires periodicity in thermal correlation functions when the temporal variable changes by an amount

Quantization of higher-derivative field theories

-i\big/(T\sqrt{g_{\bar{00}}})

Thermal Green functions in coordinate space for massless particles of any spin

. Light front quantization fails since