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HEP/Astro Journal Club -- Friday, 12 May 2000
Power-suppressed Thermal Effects from Heavy Particles
Abstract
In quantum field theory, heavy particles with mass M much greater than
the temperature T give not only effects suppressed by the Boltzmann
factor e-M/T, but also effects suppressed by powers of
T/M. We show that power-suppressed terms in equilibrium observables
arise from effective interactions among light particles due to virtual heavy
particles. We study a model introduced by Matsumoto and Yoshimura in which
heavy bosons interact only through a term that allows pair annihilation into
light particles. We construct an effective Lagrangian for the light field by
integrating out the heavy field, and use it to calculate the leading
power-suppressed terms in the energy density. The thermal average of the
Hamiltonian density for the heavy field includes a term proportional to
T6/M2, but we show that this term can be
eliminated by a field redefinition and therefore cannot have any physical
significance.
Reference
E. Braaten and Y. Jia, "Power-suppressed Thermal Effects from Heavy Particles,"
[hep-ph/0003135].
2:30pm, Smith Lab 4079