Backgrounds in gravitational effective field theory

Quark-sector Lorentz violation in Z-boson production

“…These principles have been tested with exceptional precision in numerous experiments involving SM particles and gravitational fields [7]. The model-independent framework for quantifying tiny deviations from exact CPT and Lorentz invariance, potentially emerging from new short-distance physics, is based on effective field theory and is known as the Standard-Model Extension (SME) [8][9][10][11]. The Lagrange density for the SME incorporates all CPT-and Lorentz-violating terms for gravitational fields coupled to the SM.…”

On Plane Wave Solutions in Lorentz-Violating Extensions of Gravity

“…In this section we consider the dispersion relations generated by additive full-fledged LV terms in the gravitational sector, as proposed in [9]. Our starting point is the following decomposition of the h µν tensor into its irreducible components originally introduced in [6] (see also [7]):…”

“…Therefore, the natural problem consists of studying plane wave solutions in gravity theories with various recently proposed LV additive terms [9,10]. This issue will be discussed in the present paper.…”

“…The structure of the paper is as follows. In Section 2, we consider the dispersion relations in modified gravity models represented as a sum of the usual Einstein-Hilbert action and terms introduced in [9]. In Section 3, we obtain the dispersion relations in theories whose action is given by a sum of the Einstein-Hilbert term and some new linearized gauge-invariant terms.…”

Implications of SU(2)L gauge invariance for constraints on Lorentz violation

“…In order to have local invariance under SU(3)c ×SU(2)L ×U(1)Y , the partial derivatives in the Lagrange density need to be suitably promoted to covariant derivatives[30,31]. Our argument relies on global gauge invariance in the lepton sector, i.e., we consider the free Lagrangian and neglect all Lorentz-violating terms in interactions and the pure gauge sector.2 Note the connection to L (d) lepton,D of table XVII in the recent paper of ref [31]. that complements the minimal (gravitational) SME by including higher-derivative contributions.…”