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arXiv · hep-th/0311176

Vacuum energy and $θ$--vacuum

M. Asorey
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Abstract

The highly non-trivial structure of the $θ$--vacuum encodes many of the fundamental properties of gauge theories. In particular, the response of the vacuum to the $θ$--term perturbation is sensitive to the existence of confinement, chiral symmetry breaking, etc. We analyze the dependence of the vacuum energy density on theta around two special values, $θ=0$ and $θ=π$. The existence or not of singular behaviors associated to spontaneous breaking of CP symmetry in these vacua has been a controversial matter for years. We clarify this important problem by means of continuum non-perturbative techniques. The results show the absence of first order cusp singularities on the vacuum energy density at $θ=0$ and $θ=π$ for some gauge theories. This smooth dependence of the energy on $θ$ might have implications for long standing cosmological problems like the baryonic asymmetry and the cosmological constant problem.

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M. Asorey. 2003-12-18. Vacuum energy and $θ$--vacuum. https://doi.org/10.1016/s0920-5632(03)02395-8

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