One-loop renormalization of Lorentz and CPT -violating scalar field theory in curved spacetime

Abstract

The one-loop divergences for the scalar field theory with Lorentz and/or CPT breaking terms are obtained in curved spacetime. We analyze two separate cases: a minimal coupled scalar field with gravity and a nonminimal one. For the minimal case with a real scalar field, the counterterms are evaluated in a nonperturbative form in the CPT-even parameter through a redefinition of a space-time metric. In the most complicated case of a complex scalar field nonminimally interacting with gravity, the solution for the divergences is obtained in the first order in the weak Lorentz violating parameter. The necessary form of the vacuum counterterms indicate the most important structures of Lorentz and CPT violations in the pure gravitational sector of the theory. The conformal theory limit is also analyzed. It turns out that if we allow the violating fields to transform, the classical conformal invariance of massless scalar fields can be maintained in the ξ ¼ 1=6 case. At a quantum level, the conformal symmetry is violated by a trace anomaly. As a result, the conformal anomaly and the anomaly induced effective action are evaluated in the presence of extra Lorentz-and/or CPT-violating parameters. Such gravitational effective action is important for cosmological applications and can be used for searching of Lorentz violation in the primordial Universe in the cosmological perturbations, especially gravitational waves.