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## Full-Text Articles in Physics

Bounds On Vacuum-Orthogonal Lorentz And Cpt Violation From Radiative Corrections, Brett Altschul

#### Bounds On Vacuum-Orthogonal Lorentz And Cpt Violation From Radiative Corrections, Brett Altschul

*Faculty Publications*

Certain forms of Lorentz violation in the photon sector are difficult to bound directly, since they are “vacuum orthogonal”—meaning they do not change the solutions of the equations of motion in vacuum. However, these very same terms have a unique tendency to contribute large radiative corrections to effects in other sectors. Making use of this, we set bounds on four previously unconstrained d = 5 photon operators at the 10 − 25 – 10 − 31 GeV − 1 levels.

Hadronic Lorentz Violation In Chiral Perturbation Theory Including The Coupling To External Fields, Rasha Kamand, Brett Altschul, Matthias R. Schindler

#### Hadronic Lorentz Violation In Chiral Perturbation Theory Including The Coupling To External Fields, Rasha Kamand, Brett Altschul, Matthias R. Schindler

*Faculty Publications*

If any violation of Lorentz symmetry exists in the hadron sector, its ultimate origins must lie at the quark level. We continue the analysis of how the theories at these two levels are connected, using chiral perturbation theory. Considering a 2-flavor quark theory, with dimension-4 operators that break Lorentz symmetry, we derive a low-energy theory of pions and nucleons that is invariant under local chiral transformations and includes the coupling to external fields. The pure meson and baryon sectors, as well as the couplings between them and the couplings to external electromagnetic and weak gauge fields, contain forms of Lorentz ...

Mode Analysis For Energetics Of A Moving Charge In Lorentz- And Cpt -Violating Electrodynamics, Richard Decosta, Brett Altschul

#### Mode Analysis For Energetics Of A Moving Charge In Lorentz- And Cpt -Violating Electrodynamics, Richard Decosta, Brett Altschul

*Faculty Publications*

In isotropic but Lorentz- and CPT -violating electrodynamics, it is known that a charge in uniform motion does not lose any energy to Cerenkov radiation. This presents a puzzle, since the radiation appears to be kinematically allowed for many modes. Studying the Fourier transforms of the most important terms in the modified magnetic field and Poynting vector, we confirm the vanishing of the radiation rate. Moreover, we show that the Fourier transform of the field changes sign between small and large wave numbers. This enables modes with very long wavelengths to carry negative energies, which cancel out the positive energies ...

Why Cerenkov Radiation May Not Occur, Even When It Is Allowed By Lorentz-Violating Kinematics, Brett Altschul

#### Why Cerenkov Radiation May Not Occur, Even When It Is Allowed By Lorentz-Violating Kinematics, Brett Altschul

*Faculty Publications*

In a Lorentz-violating quantum field theory, the energy-momentum relations for the field quanta are typically modified. This affects the kinematics, and processes that are normally forbidden may become allowed. One reaction that clearly becomes kinematically possible when photons’ phase speeds are less than 1 is vacuum Cerenkov radiation. However, in spite of expectations, and in defiance of phase space estimates, a electromagnetic Chern–Simons theory with a timelike Lorentz violation coefficient does not feature any energy losses through Cerenkov emission. There is an unexpected cancelation, made possible by the existence of unstable long-wavelength modes of the field. The fact that ...