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Articles 1 - 16 of 16
Full-Text Articles in Physics
Superluminal Propagation On A Moving Braneworld, Brian Greene, Daniel Kabat, Janna Levin, Arjun S. Menon
Superluminal Propagation On A Moving Braneworld, Brian Greene, Daniel Kabat, Janna Levin, Arjun S. Menon
Publications and Research
We consider a braneworld scenario in the simplest setting, M4 × S1, with a four-dimensional (4D) Minkowski metric induced on the brane, and establish the possibility of superluminal propagation. If the brane is at rest, the 4D Lorentz symmetry of the brane is exact, but if the brane is in motion, it is broken globally by the compactification. By measuring bulk fields, an observer on the brane sees a slice through a higher-dimensional field profile, which carries an imprint of the extra dimensions even when the brane is at rest. If the brane is in motion, we …
Lorentz- And C P T -Violating Standard Model Extension In Chiral Perturbation Theory, Brett Altschul, Matthias R. Schindler
Lorentz- And C P T -Violating Standard Model Extension In Chiral Perturbation Theory, Brett Altschul, Matthias R. Schindler
Faculty Publications
Lorentz and CPT violation in hadronic physics must be tied to symmetry violations at the underlying quark and gluon level. Chiral perturbation theory provides a method for translating novel operators that may appear in the Lagrange density for color-charged parton fields into equivalent forms for effective theories at the meson and baryon levels. We extend the application of this technique to the study of Lorentzviolating and potentially CPT-violating operators from the minimal standard model extension. For dimension-4 operators, there are nontrivial relations between the coefficients of baryon-level operators related to underlying quark and gluon operators with the same Lorentz structures. …
New Tests Of General Relativity, Quentin Bailey
New Tests Of General Relativity, Quentin Bailey
Quentin Bailey
The last decade has seen a rapid increase in the number of precision tests of relativity. This research has been motivated by the intriguing possibility that tiny deviations from relativity might arise in the underlying theory that is widely believed to successfully mesh General Relativity (GR) with quantum physics. Many of these tests have been analyzed within an effective field theory framework which generically describes possible deviations from exact relativity and contains some traditional test frameworks as limiting cases. One part of the activity has been a resurgence of interest in tests of relativity in the Minkowski-spacetime context, where Lorentz …
Lorentz-Violating Electromagnetostatics, Quentin G. Bailey
Lorentz-Violating Electromagnetostatics, Quentin G. Bailey
Quentin Bailey
In this talk, the stationary limit of Lorentz-violating electrodynamics is discussed. As illustrated by some simple examples, the general solution includes unconventional mixing of electrostatic and magnetostatic effects. I discuss a high-sensitivity null-type measurement, exploiting Lorentz-violating electromagnetostatic effects, that could improve existing limits on parity-odd coefficients for Lorentz violation in the photon sector.
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 David Altschul, Matthias R. Schindler
Hadronic Lorentz Violation In Chiral Perturbation Theory Including The Coupling To External Fields, Rasha Kamand, Brett David 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 …
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 the …
Velocity-Dependent Inverse Cubic Force And Solar System Gravity Tests, Quentin G. Bailey, Daniel Havert
Velocity-Dependent Inverse Cubic Force And Solar System Gravity Tests, Quentin G. Bailey, Daniel Havert
Publications
Higher mass dimension terms in an effective field theory framework for tests of spacetime symmetries are studied. Using a post-Newtonian expansion method, we derive the spacetime metric and the equations of motion for a binary system. This reveals an effective inverse cubic force correction to post-Newtonian general relativity that depends on the velocity of the bodies in the system. The results are studied in the context of laboratory and space-based tests including the effects on solar-system ephemeris, laser ranging observations, and gravimeter tests. This work reveals the coefficient combinations for mass dimension 5 operators controlling CPT violation for gravity that …
Limits On Violations Of Lorentz Symmetry From Gravity Probe B, Quentin G. Bailey, Ryan D. Everett, James M. Overduin
Limits On Violations Of Lorentz Symmetry From Gravity Probe B, Quentin G. Bailey, Ryan D. Everett, James M. Overduin
Quentin Bailey
Generic violations of Lorentz symmetry can be described by an effective field theory framework that contains both general relativity and the Standard Model of particle physics called the Standard-Model extension (SME). We obtain new constraints on the gravitational sector of the SME using recently published final results from Gravity Probe B. These include for the first time an upper limit at the 10_3 level on the time-time component of the new tensor field responsible for inducing local Lorentz violation in the theory, and an independent limit at the 10_7 level on a combination of components of this tensor field.
Limits On Violations Of Lorentz Symmetry From Gravity Probe B, Quentin G. Bailey, Ryan D. Everett, James M. Overduin
Limits On Violations Of Lorentz Symmetry From Gravity Probe B, Quentin G. Bailey, Ryan D. Everett, James M. Overduin
Physics & Astronomy - Prescott
Generic violations of Lorentz symmetry can be described by an effective field theory framework that contains both general relativity and the Standard Model of particle physics called the Standard-Model extension (SME). We obtain new constraints on the gravitational sector of the SME using recently published final results from Gravity Probe B. These include for the first time an upper limit at the 10_3 level on the time-time component of the new tensor field responsible for inducing local Lorentz violation in the theory, and an independent limit at the 10_7 level on a combination of components of this tensor field.
Coupling Right- And Left-Handed Photons Differently To Charged Matter, Brett David Altschul
Coupling Right- And Left-Handed Photons Differently To Charged Matter, Brett David Altschul
Faculty Publications
We consider a modification of electrodynamics in which right- and left-circularly polarized photons are coupled to charged sources differently. Even though photon helicity is a Lorentz invariant quantity, such a modification breaks Lorentz symmetry, as well as locality. The modified theory includes novel magnetic forces between perpendicular currents. Existing data can be used to constrain the modification at approximately a 2 x 10^(-3) level.
New Tests Of General Relativity, Quentin Bailey
New Tests Of General Relativity, Quentin Bailey
Publications
The last decade has seen a rapid increase in the number of precision tests of relativity. This research has been motivated by the intriguing possibility that tiny deviations from relativity might arise in the underlying theory that is widely believed to successfully mesh General Relativity (GR) with quantum physics. Many of these tests have been analyzed within an effective field theory framework which generically describes possible deviations from exact relativity and contains some traditional test frameworks as limiting cases. One part of the activity has been a resurgence of interest in tests of relativity in the Minkowski-spacetime context, where Lorentz …
Vector Theory Of Spontaneous Lorentz Violation, Shu Hong Fung
Vector Theory Of Spontaneous Lorentz Violation, Shu Hong Fung
Honors Theses
Classical electromagnetism predicts two massless propagating modes, which are known as the two polarizations of the photon. On the other hand, if the Lorentz symmetry of classical electromagnetism is spontaneously broken, the new theory will still have two massless Nambu-Goldstone modes resembling the photon. If the Lorentz symmetry is broken by a bumblebee potential that allows for excitations out of the minimum, then massive modes arise. Furthermore, in curved spacetime, such massive modes will be created through a process other than the usual Higgs mechanism because of the dependence of the bumblebee potential on both the vector field and the …
Lorentz-Violating Electromagnetostatics, Quentin G. Bailey
Lorentz-Violating Electromagnetostatics, Quentin G. Bailey
Publications
In this talk, the stationary limit of Lorentz-violating electrodynamics is discussed. As illustrated by some simple examples, the general solution includes unconventional mixing of electrostatic and magnetostatic effects. I discuss a high-sensitivity null-type measurement, exploiting Lorentz-violating electromagnetostatic effects, that could improve existing limits on parity-odd coefficients for Lorentz violation in the photon sector.