Vacuum energy of one-dimensional supercritical Dirac-Coulomb system. (arXiv:1709.04239v1 [hep-th])

Nonperturbative vacuum polarization effects are explored for a supercritical
Coulomb source with $Z>Z_{cr}$ in 1+1 D. Both the vacuum charge density
$\rho_{vac}(x)$ and vacuum energy $E_{vac}$ are considered. It is shown that in
the overcritical region the behavior of vacuum energy could be significantly
different from perturbative quadratic growth up to decrease reaching large
negative values.

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