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Scattering amplitude and shift in self-energy in medium
Two simple proofs are presented for the first order virial expansion of the
self-energy of a particle moving through a medium, characterised by temperature
and/or chemical potential(s). One is based on the virial expansion of the
self-energy operator itself, while the other is on the analysis of its Feynman
diagrams in configuration space.Comment: 6 pages, revtex, with 1 eps figur
Current algebra derivation of temperature dependence of hadron couplings with currents
The vector and the axial-vector meson couplings with the vector and the
axial-vector currents respectively at finite temperature have been obtained in
Ref. \cite{Mallik} by calculating all the relevant one-loop Feynman graphs with
vertices obtained from the effective chiral Lagrangian. On the other hand, the
same couplings were also derived in Ref.\cite{Ioffe1} by applying the method of
current algebra and the hypothesis of partial conservation of axial-vector
current (PCAC). The latter method appears to miss certain terms; in the case of
the vector meson coupling with the vector current, for example, a term
containing the coupling is missed. A similar situation would
also appear for the nucleon coupling with the nucleon current. In this note we
resolve these differences.Comment: 7 pages, 2 eps figure
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