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arXiv · 0806.1669

Spontaneous CP-violation in the strong interaction at theta = pi

Daniel Boer·Jorn K. Boomsma
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Abstract

Spontaneous CP-violation in the strong interaction is analyzed at theta = pi within the framework of the two-flavor NJL model. It is found that the occurrence of spontaneous CP-violation at theta = pi depends on the strength of the 't Hooft determinant interaction, which describes the effect of instanton interactions. The dependence of the phase structure, and in particular of the CP-violating phase, on the quark masses, temperature, baryon and isospin chemical potential is examined in detail. When available a comparison to earlier results from chiral perturbation theory is made. From our results we conclude that spontaneous CP-violation in the strong interaction is an inherently low-energy phenomenon. In all cases we find agreement with the Vafa-Witten theorem, also at nonzero density and temperature. Meson masses and mixing in the CP-violating phase display some unusual features as a function of instanton interaction strength. A modification of the condition for charged pion condensation at nonzero isospin chemical potential and a novel phase of charged a_0 mesons are discussed.

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Daniel Boer, Jorn K. Boomsma. 2008-09-26. Spontaneous CP-violation in the strong interaction at theta = pi. https://doi.org/10.1103/physrevd.78.054027

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