Studies in Spacetime Symmetries
Studies in Spacetime Symmetries
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I am interested in foundational tests of our best current fundamental theories of physics, the theory of gravity, General Relativity, and the Standard Model of particle physics. So far, I have been studying the theoretical and experimental aspects of testing the Einstein Equivalence Principle, a foundation of General Relativity. In particular I have focused on tests of Lorentz symmetry, the spacetime symmetry of Special Relativity, and also the discrete spacetime symmetry called CPT. The motivation for this work is twofold. First, spacetime symmetries are cornerstone of modern physics. As such, it should be an experimental precedent to test these principle in as many ways as possible. Second, recent work on fundamental theories of physics, that attempt to unify the Standard Model of particle physics and General Relativity, has pointed to the possibility of deviations from perfect spacetime symmetry. In the ongoing search for new physics in turns out that high-precision, typically low-energy tests of Lorentz and CPT symmetry offer a promising alternative to conventional high-energy accelerator experiments.Â
I am interested in foundational tests of our best current fundamental theories of physics, the theory of gravity, General Relativity, and the Standard Model of particle physics. So far, I have been studying the theoretical and experimental aspects of testing the Einstein Equivalence Principle, a foundation of General Relativity. In particular I have focused on tests of Lorentz symmetry, the spacetime symmetry of Special Relativity, and also the discrete spacetime symmetry called CPT. The motivation for this work is twofold. First, spacetime symmetries are cornerstone of modern physics. As such, it should be an experimental precedent to test these principle in as many ways as possible. Second, recent work on fundamental theories of physics, that attempt to unify the Standard Model of particle physics and General Relativity, has pointed to the possibility of deviations from perfect spacetime symmetry. In the ongoing search for new physics in turns out that high-precision, typically low-energy tests of Lorentz and CPT symmetry offer a promising alternative to conventional high-energy accelerator experiments.Â
Publications
"Bumblebee gravity: spherically-symmetric solutions away from the potential minimum", submitted for publication, archived pre-print link
"You shall not pass! -- explicit diffeomorphism violation "no-go" results," Physical Review D 110 (2024) 084066, archived pre-print link
Classical radiation fields for scalar, electromagnetic, and gravitational waves with spacetime-symmetry breaking, Annals of Physics 461 (2024) 169582 archived pre-print link
Testing Gravity in the Laboratory, review article, archived pre-print link
Search for anisotropic, birefringent spacetime-symmetry breaking in gravitational wave propagation from GWTC-3, Phys.Rev.D 107 (2023) 6, 064031, archived pre-print link
Short-range forces due to Lorentz-symmetry violation, Class. Quantum Grav. 40 045006 (2023) , archived pre-print link
New Signals in Precision Gravity Tests and Beyond, Presented at the Ninth Meeting on CPT and Lorentz Symmetry, Bloomington, Indiana, May 17-26 link
Analysis of birefringence and dispersion effects from spacetime-symmetry breaking in gravitational waves, accepted to Universe link
Construction of higher-order metric fluctuation terms in spacetime symmetry-breaking effective field theory Symmetry 13, 834 (2021), link
Constraining velocity-dependent Lorentz/CPT-violations using Lunar Laser Ranging Phys. Rev. D 103, 064055 (2021) link
A 3+1 Formulation of the Standard-Model Extension Gravity Sector Phys. Rev. D 103,044010 (2021) link
"New Test of Lorentz Invariance Using the MICROSCOPE Space Mission" Phys. Rev. Lett. 123, 231102 (2019) link
"A 3+1 Decomposition of the minimal Standard-Model Extension Gravitational Sector" presented by Albin Nilsson at the Eighth Meeting on CPT and Lorentz Symmetry, May 2019 link
"Testing the Gravitational Weak Equivalence Principle in the Standard-Model Extension with Binary Pulsars" Phys. Rev. D 99, 084017 (2019) link
"Testing velocity-dependent CPT-violating gravitational forces with radio pulsars" Phys. Rev. D 98, 084049 (2018) link
Relating Noncommutative SO(2,3)* Gravity to the Lorentz-Violating Standard-Model Extension, Symmetry 2018, 10, 480 link
Velocity-dependent inverse cubic force and solar-system gravity tests, Phys. Rev. D 96, 064035 (2017) link
Lorentz-symmetry test at Planck-scale suppression with nucleons in a spin-polarized Cesium cold atom clock, (with Helene Pihan-Le Bars et al), Phys. Rev. D 95, 075026 (2017) link
Tests of Lorentz symmetry in the gravitational sector, with Aurelien Hees et al, review article, Universe 2, 4 (2016) link
Anisotropic cubic curvature couplings, Phys. Rev. D 94, 065029 (2016) link
Constraints on SME coefficients from Lunar Laser Ranging, Very Long Baseline Interferometry, and Asteroid Dynamics, (with C. Le Poncin-Lafitte et al) presented at the Seventh Meeting on CPT and Lorentz Symmetry, June 2016, link
Gravity Sector of the SME, presented at the Seventh Meeting on CPT and Lorentz Symmetry, June 2016, link
Combined search for Lorentz violation in short-range gravity (with C.G. Shao et al), Phys. Rev. Lett. 117, 071102 (2016) link
Testing Lorentz symmetry with planetary dynamics (with A. Hees et al.) Phys. Rev. D 92, 064049 (2015) link
What do we know about Lorentz symmetry? presented at the 50th Rencontres de Moriond, "Gravitation: 100 years after GR" link
Short-range gravity and Lorentz violation, (with V.A. Kostelecky and Rui Xu), Phys. Rev. D 91 , 022006 (2015) [TOPCITE 100+] link
Quantum Tests of the Einstein Equivalence Principle with the STE-QUEST Space Mission, Advances in Space Research 55, 501 (2015) link
Limits on violations of Lorentz Symmetry from Gravity Probe B, Phys. Rev. D 88, 102001 (2013) (with J. Overduin and R. Everett) link
Local Lorentz-Symmetry Breaking and Gravity, presented at the Sixth Meeting on CPT and Lorentz Symmetry, June 2013, link
Constraints on violations of Lorentz Symmetry from Gravity Probe B, (with J. Overduin and R. Everett), presented at the Sixth Meeting on CPT and Lorentz Symmetry, June 2013, link
Light-bending tests of Lorentz invariance, (with undergraduate Rhondale Tso), Phys. Rev. D 84, 085025 (2011) link
New tests of General Relativity, in Matters of Gravity, The Newsletter of the Topical Group on Gravitation of the American Physical Society, Volume 36, Fall 2010 link
Gravity Couplings in the Standard-Model Extension, in CPT and Lorentz Symmetry V, World Scientific, 2011. link
Gravitational Lensing and Light Bending as tests of Lorentz Symmetry,(with Rhondale Tso), in CPT and Lorentz Symmetry V, World Scientific, 2011.
Lorentz-violating gravitoelectromagnetism, Phys. Rev. D 82, 065012 (2010). [TOPCITE 50+] link
Lorentz violation with an antisymmetric tensor, (with B. Altschul and V.A. Kostelecky), Phys. Rev. D 81, 065028 (2010). [TOPCITE 100+] link
Lorentz Violation and Gravity, in Proceedings of the International Astronomical Union (IAU) Symposium 261: Relativity in Fundamental Astronomy, 2009. link
Catching relativity violations with atoms, Physics 2, 58, 2009. link
Time-delay and Doppler tests of the Lorentz symmetry of gravity,Phys. Rev. D 80, 044004 (2009). [TOPCITE 50+] link
Testing Lorentz Symmetry with Gravity, in CPT and Lorentz Symmetry IV, World Scientific, 2008. link
Lorentz Violation and Gravity, Ph.D. dissertation, Indiana University, 2007.
Signals for Lorentz Violation in Post-Newtonian Gravity (with V.A. Kostelecky), Phys. Rev. D 74, 045001 (2006). [TOPCITE 400+] link
Lorentz-Violating Electromagnetostatics, in CPT and Lorentz Symmetry III, World Scientific, 2005. link
Lorentz-Violating Electrostatics and Magnetostatics (with V.A. Kostelecky), Phys. Rev. D 70, 076006 (2004). [TOPCITE 200+] link
In the SME formalism, Lorentz violation for a given particle type (species) is described by its coefficients for Lorentz violation. In certain special cases, we can visualize these coefficients as a background field of arrows, pointing in some direction, that affects our measuring apparatus (rods and clocks) as they move or rotate through the background. This is illustrated in the animation above for blue and green rods and clocks. As the two sets of rods and clocks rotate their relative lengths and ticking rates will change if Lorentz symmetry is violated. If deviations from perfect Lorentz symmetry occur in nature, they must be miniscule. This implies that the best method for finding Lorentz violation is to use the most sensitive "rods" and "clocks" available with today's technology.
In practice, a variety of real physical systems can be used as effective rods and clocks. For example, some of the systems that have been used to test Lorentz symmetry include hydrogen atoms, cesium atoms, torsion pendula, superconducting gravimeters, electromagnetic resonant cavities, the Earth-Moon system, and even distant light propagating from the early universe.
For weak gravitational fields, there are nine independent coefficients for Lorentz violation in the pure-gravity sector of the (minimal) SME. These coefficients would vanish in the limit that (local) Lorentz symmetry holds for gravity. Searches for nonzero gravity coefficients include a variety of laboratory experiments, solar-system observations, and beyond. For example, analysis of lunar laser ranging data can place stringent constraints on these coefficients. In the figure below, Lorentz violation (arrows) could cause the Moon to deviate from its usual elliptical path.
Kostelecky and Tasson have analyzed matter-gravity couplings in the SME framework. Their work reveals new types of unexplored signals for Lorentz violation in gravitational tests:
Matter-gravity couplings and Lorentz violation, Alan Kostelecky and Jay Tasson link
Prospects for Large Relativity Violations in Matter-Gravity Couplings, Alan Kostelecky and Jay Tasson link
More recently, Bailey, Kostelecky, Mewes, Tasson and Xu have studied the gravity sector nonminimal SME in a series of publications. This introduces a large number of coefficients classified by the mass dimension of the operators appearing in the lagrangian. These coefficients can be measured in precision short-range gravity tests as well as gravitational wave measurements. The publications on the nonminimal gravitational SME include:
Short-range gravity and Lorentz violation, (with V.A. Kostelecky and Rui Xu), Phys. Rev. D 91 , 022006 (2015) link
Constraints on Lorentz Violation from Gravitational Cherenkov Radiation, Phys. Lett. B 749, 551 (2015) link
Testing local Lorentz invariance with gravitational waves, Phys. Lett. B 757, 510 (2016) link
There are nineteen independent coefficients for Lorentz violation in the "minimal" version of the photon sector of the SME. Astrophysical observations and laboratory resonant-cavity tests have probed for these photon coefficients. Lorentz violation could also affect other known particles, such as neutrinos, and many experiments have already been performed.
So far, no statistically convincing evidence exists that any coefficients for Lorentz violation are nonzero. However, future experiments may dramatically improve existing sensitivities, and may yet discover miniscule Lorentz violation.
Gravity sector experimental/observational analyses using the SME framework
Gravity sector experimental/observational analyses using the SME framework
Probing of violation of Lorentz invariance by ultracold neutrons in the Standard Model Extension, A.N. Ivanov et al, accepted in Physics Letters B link
Gravitational Waves and Gamma-Rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A, B. Abbott et al. (LSC collaboration), Astrophys. J. 848, L2 (2017) link
Limits on Lorentz violation in gravity form worldwide superconducting gravimeters, accepted in Physical Review D link
Lorentz symmetry violations from matter-gravity couplings with Lunar Laser Ranging, A. Bourgoin et al., submitted for publication link
Superconducting Gravimeter Tests of Local Lorentz Invariance, N. Flowers et al., accepted in Phys. Rev. Lett. link
Testing Lorentz symmetry with Lunar Laser Ranging, A. Bourgoin et al., Phys. Rev. Lett. 117, 241301 (2016) link
Lorentz symmetry and Very Long Baseline Interferometry, C. Le Poncin-Lafitte, A. Hees, and S. Lambert, Phys. Rev. D 94, 125030 (2016) link
Tests of gravitation with Gaia observations of Solar System Objects, A. Hees, D. Hestroffer, C. Le Poncin-Lafitte, and P. David link
Search for Lorentz invariance through tests of the gravitational inverse square law at short-ranges, C.G. Shao et al., Phys. Rev. D 91, 102007 (2015) link
Search for Lorentz violation in short-range gravity, J.C. Long and V.A. Kostelecky, Phys. Rev. D 91, 092003 (2015) link
New pulsar limit on local Lorentz invariance violation of gravity in the standard-model extension,Lijing Shao, Phys. Rev. D 90, 122009 (2014) link
Tests of local Lorentz invariance violation of gravity in the standard model extension with pulsars,Lijing Shao, Phys. Rev. Lett. 112, 111103 (2014) link
Equivalence Principle and Bound Kinetic Energy, Michael Hohensee, Holger Mueller, and R.B. Wiringa link
Simulations of Solar System observations in alternative theories of gravity, Aurelien Hees et al., proceedings of the 13th Marcel Grossmann Meeting link
Orbital effects of Lorentz-violating Standard Model Extension gravitomagnetism around a static body: a sensitivity analysis, Lorenzo Iorio, Class. Quant. Grav. 29, 175007 (2012) link
Equivalence Principle and Gravitational Redshift, Michael Hohensee, Steven Chu, Achim Peters, Holger Mueller, Phys. Rev. Lett. 106, 151102 (2011). link
Gravitational Redshift, Equivalence Principle, and Matter Waves, Michael Hohensee et al. link
Search for Lorentz Violation in a High-Frequency Gravitational Experiment below 50 microns, D. Bennet, V. Skavysh, and J. Long, presented at the Fifth Meeting on CPT and Lorentz Symmetry link
Atom interferometry tests of local Lorentz invariance in gravity and electrodynamics, Keng-Yeow Chung, Sheng-wey Chiow, Sven Herrmann, Steven Chu, Holger Mueller, Phys. Rev. D 80, 016002 (2009). link
Atom interferometry tests of the isotropy of post-Newtonian gravity, Holger Mueller, Sheng-wey Chiow, Sven Herrmann, Steven Chu, Keng-Yeow Chung, Phys. Rev. Lett. 100, 031101 (2008). link
Search for Lorentz Violation in a High-Frequency Gravitational Experiment below 50 microns, Joshua Long, in V.A. Kostelecky (editor), CPT and Lorentz Symmetry IV, World Scientific, 2008.
Testing for Lorentz Violation: Constraints on Standard-Model Extension Parameters via Lunar Laser Ranging, James B.R. Battat , John F. Chandler, Christopher W. Stubbs, Phys. Rev. Lett. 99, 241103 (2007). link
From Gravity Probe B to STEP: Testing Einstein in Space, James Overduin, in V.A. Kostelecky (editor), CPT and Lorentz Symmetry IV, World Scientific, 2008.
Atom Interferometry Experiments in Fundamental Physics, Holger Mueller, in V.A. Kostelecky (editor), CPT and Lorentz Symmetry IV, World Scientific, 2008.
A summary of the current experimental constraints on the many coefficients for Lorentz violation in the SME can be found here.
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