Breakdown Of Lorentz Symmetry Research Articles

Dyson-Schwinger equation approach to Lorentz symmetry breaking with finite temperature and chemical potential

In this work, we investigate the dynamical breakdown of Lorentz symmetry in 4 dimensions by the condensation of a fermionic field described by a Dirac Lagrangian with a four-fermion interaction. Using the Keldysh formalism we show that the Lorentz symmetry breaking modifies the Dyson-Schwinger equations of the fermionic propagator. We analyze the nonperturbative solutions for the Dyson-Schwinger equations using the combination of the rainbow and quenched approximations and show that, in equilibrium, the Lorentz symmetry breakdown can occur in the strong coupling regime and new features arise from this approach. Finally, we analyze the contributions of temperature and chemical potential and find the respective phase diagram of the model and analyze the dependence of the critical temperature and chemical potential as functions of the coupling constant.

Lorentz violation and gravitoelectromagnetism: Casimir effect and Stefan-Boltzmann law at finite temperature

The standard model and general relativity are local Lorentz invariants. However, it is possible that at Planck scale there may be a breakdown of Lorentz symmetry. Models with Lorentz violation are constructed using Standard Model Extension (SME). Here the gravitational sector of the SME is considered to analyze the Lorentz violation in gravitoelectromagnetism (GEM). Using the energy-momentum tensor, the Stefan-Boltzmann law and Casimir effect are calculated at finite temperature to ascertain the level of local Lorentz violation. The Thermo Field Dynamics (TFD) formalism is used to introduce temperature effects.

Møller scattering and Lorentz-violating Z bosons

Lorentz-symmetry breakdown in weak-interaction physics is studied. In particular, the CPT-even Lorentz-violating contributions to the Z boson in the minimal Standard-Model Extension are considered, and in this context polarized electron–electron scattering is investigated. Corrections to the usual parity-violating asymmetry are determined at tree level. Together with available data, this result can be used to improve existing estimates for the Lorentz-violating kW coefficient by two orders of magnitude. Some implications for past and future experiments are mentioned.

Radiative corrections to Lorentz-invariance violation with higher-order operators: Fine-tuning problem revisited

We study the possible effects of large Lorentz violations that can appear in the effective models in which the Lorentz symmetry breakdown is performed with higher-order operators. For this we consider the Myers and Pospelov extension of QED with dimension-five operators in the photon sector and standard fermions. We focus on the fermion self-energy at one-loop order and find small and finite radiative corrections in the even CPT sector. In the odd CPT sector a lower dimensional operator is generated which contains unsuppressed effects of Lorentz violation leading to a possible fine-tuning. For the calculation of divergent diagrams we use dimensional regularization and consider an arbitrary background four-vector.

Critical points in a relativistic bosonic gas induced by the quantum structure of spacetime

It is well known that phase transitions arise if the interaction among particles embodies an attractive as well as a repulsive contribution. In this work it will be shown that the breakdown of Lorentz symmetry, characterized through a deformation in the relation dispersion, plus the bosonic statistics predict the emergence of critical points. In other words, in some quantum gravity models the structure of spacetime implies the emergence of critical points even when no interaction among the particles has been considered.

Matter interactions of a three-dimensional gauge theory

A recently introduced three-dimensional gauge theory involves a tensor field Tμν. In this paper we show how this field can interact with matter fields in a gauge-invariant fashion. The possibility of spontaneous breakdown of Lorentz symmetry is considered. An additional gauge-invariant interaction for Tμν is introduced. The field Tμν interacts with gravity; we compute the η function associated with the graviton propagator and show that it is proportional to the bilinear term in the Chem–Simons action for gravity in three dimensions.