BREAKING CHIRAL SYMMETRY IN QED WITH EXTERNAL ELECTROMAGNETIC-FIELDS

Much evidence has accumulated that quantum electrodynamics may have a non-perturbative phase, especially characterized by spontaneously broken chiral symmetry. It has been proposed that this new phase of QED may have been seen in the heavy-ion collision experiments at GSI: the narrow peaks in the e+e- coincidence data are well-explained as composite states of e+e- in this new phase of QED. We present some new, direct evidence, based on computer simulations of the proper-time path integral, that background electromagnetic field configurations similar to those in the experiments can support a non-zero expectation value of psi-psi-BAR.