scholarly journals New pulsar limit on local Lorentz invariance violation of gravity in the standard-model extension

2014 ◽  
Vol 90 (12) ◽  
Author(s):  
Lijing Shao
Keyword(s):  
Standard Model ◽  
Lorentz Invariance ◽  
Standard Model Extension ◽  
Invariance Violation ◽  
Model Extension ◽  
The Standard Model ◽  
Lorentz Invariance Violation ◽  
Local Lorentz Invariance

scholarly journals Constraints on Lorentz Invariance Violation from Optical Polarimetry of Astrophysical Objects

Symmetry ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 596 ◽  
Author(s):  
Fabian Kislat
Keyword(s):  
Standard Model ◽  
Quantum Gravity ◽  
Linear Polarization ◽  
Lorentz Invariance ◽  
Polarization Angle ◽  
Standard Model Extension ◽  
Polarization Measurements ◽  
Invariance Violation ◽  
The Standard Model ◽  
Lorentz Invariance Violation

Theories of quantum gravity suggest that Lorentz invariance, the fundamental symmetry of the Theory of Relativity, may be broken at the Planck energy scale. While any deviation from conventional Physics must be minuscule in particular at attainable energies, this hypothesis motivates ever more sensitive tests of Lorentz symmetry. In the photon sector, astrophysical observations, in particular polarization measurements, are a very powerful tool because tiny deviations from Lorentz invariance will accumulate as photons propagate over cosmological distances. The Standard-Model Extension (SME) provides a theoretical framework in the form of an effective field theory that describes low-energy effects due to a more fundamental quantum gravity theory by adding additional terms to the Standard Model Lagrangian. These terms can be ordered by the mass dimension d of the corresponding operator and lead to a wavelength, polarization, and direction dependent phase velocity of light. Lorentz invariance violation leads to an energy-dependent change of the Stokes vector as photons propagate, which manifests itself as a rotation of the polarization angle in measurements of linear polarization. In this paper, we analyze optical polarization measurements from 63 Active Galactic Nuclei (AGN) and Gamma-ray Bursts (GRBs) to search for Lorentz violating signals. We use both spectropolarimetric measurements, which directly constrain the change of linear polarization angle, as well as broadband spectrally integrated measurements. In the latter, Lorentz invariance violation manifests itself by reducing the observed net polarization fraction. Any observation of non-vanishing linear polarization thus leads to constraints on the magnitude of Lorentz violating effects. We derive the first set limits on each of the 10 individual birefringent coefficients of the minimal SME with d = 4 , with 95% confidence limits on the order of 10−34 on the dimensionless coefficients.

scholarly journals Signatures of Lorentz Violation in Continuous Gravitational-Wave Spectra of Ellipsoidal Neutron Stars

Galaxies ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 12
Author(s):  
Rui Xu ◽  
Yong Gao ◽  
Lijing Shao
Keyword(s):  
Neutron Stars ◽  
Second Harmonic ◽  
Lorentz Invariance ◽  
Lorentz Violation ◽  
Wave Spectra ◽  
Standard Model Extension ◽  
Invariance Violation ◽  
Model Extension ◽  
Lorentz Invariance Violation ◽  
Frequency Components

We studied the effects of the Lorentz invariance violation on the rotation of neutron stars (NSs) in the minimal gravitational Standard-Model Extension framework, and calculated the quadrupole radiation generated by them. Aiming at testing Lorentz invariance with observations of continuous gravitational waves (GWs) from rotating NSs in the future, we compared the GW spectra of a rotating ellipsoidal NS under Lorentz-violating gravity with those of a Lorentz-invariant one. The former were found to possess frequency components higher than the second harmonic, which does not happen for the latter, indicating those higher frequency components to be potential signatures of Lorentz violation in continuous GW spectra of rotating NSs.

scholarly journals A test of local Lorentz invariance with Compton scattering asymmetry

2016 ◽  
Vol 31 (38) ◽  
pp. 1650220 ◽  
Author(s):  
Prajwal Mohanmurthy ◽  
Amrendra Narayan ◽  
Dipangkar Dutta
Keyword(s):  
Refractive Index ◽  
Standard Model ◽  
Compton Scattering ◽  
Electron Scattering ◽  
Lorentz Invariance ◽  
Speed Of Light ◽  
Standard Model Extension ◽  
Model Extension ◽  
Minimal Standard ◽  
Local Lorentz Invariance

We report on a measurement of the constancy and anisotropy of the speed of light relative to the electrons in photon–electron scattering. We used the Compton scattering asymmetry measured by the new Compton polarimeter in Hall C at Jefferson Lab (JLab) to test for deviations from unity of the vacuum refractive index (n). For photon energies in the range of 9–46 MeV, we obtain a new limit of 1 − n < 1.4 × 10[Formula: see text]. In addition, the absence of sidereal variation over the six-month period of the measurement constrains any anisotropies in the speed of light. These constitute the first study of Lorentz invariance (LI) using Compton asymmetry. Within the minimal Standard Model extension (MSME) framework, our result yield limits on the photon and electron coefficients [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text]. Although these limits are several orders of magnitude larger than the current best limits, they demonstrate the feasibility of using Compton asymmetry for tests of LI. Future parity-violating electron-scattering experiments at JLab will use higher energy electrons enabling better constraints.

scholarly journals Constraints on the standard model extension with binary pulsars

2012 ◽  
Vol 8 (S291) ◽  
pp. 558-560
Author(s):  
Yi Xie
Keyword(s):  
Standard Model ◽  
Lorentz Invariance ◽  
Standard Model Extension ◽  
Binary Pulsars ◽  
Model Extension ◽  
The Standard Model ◽  
Order Of Magnitude ◽  
Dimensionless Combination

AbstractUnder the standard model extension (SME) framework, Lorentz invariance is tested in five binary pulsars: PSR J0737-3039, PSR B1534+12, PSR J1756-2251, PSR B1913+16 and PSR B2127+11C. By analyzing the advance of periastron, we obtain the constraints on a dimensionless combination of SME parameters that is sensitive to timing observations. The results imply no evidence for the break of Lorentz invariance at 10−10 level, one order of magnitude larger than previous estimation.

SEARCH FOR CPT AND LORENTZ INVARIANCE VIOLATION IN NEUTRAL KAONS AT KLOE/KLOE–2

2014 ◽  
Vol 35 ◽  
pp. 1460434
Author(s):  
ERYK CZERWIŃSKI ◽  
Keyword(s):  
Lorentz Invariance ◽  
Entangled State ◽  
Cpt Symmetry ◽  
Standard Model Extension ◽  
Neutral Kaons ◽  
Invariance Violation ◽  
Decay Times ◽  
Model Extension ◽  
The Standard Model ◽  
The Difference

Measurement of the difference of the decay times of neutral kaon pairs produced in an antisymmetric entangled state allows for the search of possible violation of CPT symmetry and Lorentz invariance. In this paper we present the recently announced results based on the reaction ϕ → KSKL → π+π-π+π- measured at the KLOE experiment. Obtained parameters in the Standard Model Extension (SME) are: [Formula: see text]

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