Effects of a Thermal Bath of Photons on Embedded String Stability
  We compute the corrections of thermal photons on the effective potential for
the linear sigma model of QCD. Since we are interested in temperatures lower
than the confinement temperature, we consider the scalar fields to be out of
equilibrium. Two of the scalar field are uncharged while the other two are
charged under the U(1) gauge symmetry of electromagnetism. We find that the
induced thermal terms in the effective potential can stabilize the embedded
pion string, a string configuration which is unstable in the vacuum. Our
results are applicable in a more general context and demonstrate that embedded
string configurations arising in a wider class of field theories can be
stabilized by thermal effects. Another well-known example of an embedded string
which can be stabilized by thermal effects is the electroweak Z-string. We
discuss the general criteria for thermal stabilization of embedded defects.
