One-loop renormalization of Lorentz/CPT violating scalar field theory in curved space-time

TL;DR

This paper calculates one-loop divergences in Lorentz/CPT violating scalar field theories in curved space-time, revealing how such violations affect gravitational sector structures and conformal symmetry at quantum level.

Contribution

It provides the first detailed analysis of one-loop divergences in Lorentz/CPT violating scalar fields in curved space, including nonperturbative and first-order solutions.

Findings

Counterterms depend on Lorentz/CPT violating parameters.

Conformal invariance can be maintained classically but is broken quantum mechanically.

Derived effective gravitational action with Lorentz/CPT violation for cosmological applications.

Abstract

The one-loop divergences for the scalar field theory with Lorentz and/or CPT breaking terms are obtained in curved space-time. We analyze two separate cases: minimal coupled scalar field with gravity and nonminimal one. For the minimal case with real scalar field, the counterterms are evaluated in a nonperturbative form in the CPT-even parameter through a redefinition of space-time metric. In the most complicated case of 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/CPT violations in the pure gravitational sector of 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 $\,\xi = 1/6\,$ case. At quantum level the conformal symmetry is violated by trace anomaly. As a result, 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 primordial universe in the cosmological perturbations, especially gravitational waves.