Tests Of Lorentz Invariance Research Articles

Energy-dependent intrinsic time delay of gamma-ray bursts on testing Lorentz invariance violation

High-energy photons of gamma-ray bursts (GRBs) might be emitted at different intrinsic times with energy dependence at the source. In this letter, we expand the model from previous works on testing the Lorentz Invariance Violation (LV) with the observed GRB data from the Fermi Gamma-ray Space Telescope. We reanalyze the previous data with the full Bayesian parameter estimation method and get consistent results by assuming that the time delays are due to an LV term and a constant intrinsic time delay term. Subsequently, we neglect the LV effect and only consider the intrinsic time delay effect. We assume a common intrinsic time delay term along with a source energy correlated time delay of high-energy photons. We find that the energy-dependent emission times can also explain the observed GRB data of high-energy photon events. Finally, we integrate these two physical mechanisms into a unified model to distinguish and evaluate their respective contributions using the observed GRB data.

Revisiting tests of Lorentz invariance with gamma-ray bursts: Effects of intrinsic lags

Revisiting tests of Lorentz invariance with gamma-ray bursts: Effects of intrinsic lags

Investigating the Lorentz invariance violation effect using different cosmological backgrounds

Familiar concepts in physics, such as Lorentz symmetry, are expected to be broken at energies approaching the Planck energy scale as predicted by several quantum-gravity theories. However, such very large energies are unreachable by current experiments on Earth. Current and future Cherenkov telescope facilities may have the capability to measure the accumulated deformation from Lorentz symmetry for photons traveling over large distances via energy-dependent time delays. One of the best natural laboratories to test Lorentz invariance violation (LIV) signatures are gamma-ray bursts. The calculation of time delays due to the LIV effect depends on the cosmic expansion history. In most of the previous works calculating time lags due to the LIV effect, the standard ΛCDM (or concordance) cosmological model is assumed. In this paper, we investigate whether the LIV signature is significantly different when assuming alternatives to the ΛCDM cosmological model. Specifically, we consider cosmological models with a non-trivial dark-energy equation of state (EoS) (), such as the standard Chevallier–Polarski–Linder parameterization, the quadratic parameterization of the dark-energy EoS, and the Pade parameterizations. We find that the relative difference in the predicted time lags is small, of the order of at most a few percent, and thus likely smaller than the systematic errors of possible measurements currently or in the near future.

Testing the scalar sector of the standard-model extension with neutron gravity experiments

In the present study we analyse, within the scalar sector of the standard-model extension framework, the influence of a spontaneous Lorentz symmetry breaking on gravitational quantum states of ultracold neutrons. The model is framed according to the laboratory conditions of the recent high-sensitivity GRANIT and qBounce experiments. The high-precision data achieved in such experiments allow us to set bounds on the symmetry breaking parameters of the model. The effective Hamiltonian governing the neutron’s motion along the axis of free fall is derived explicitly. It describes a particle in a gravitational field with an effective gravitational constant controlled non-trivially by the Lorentz-violating parameters. In particular, using the exact wave functions and the energy spectrum, we evaluate both the heights associated with the quantum states and the transition frequencies between neighborhoring quantum states. By comparing our theoretical results with those reported in the GRANIT and the qBounce experiments, upper bounds on the Lorentz-violating parameters are determined. We also consider for the first time the gravity-induced interference pattern in a COW-type experiment to test Lorentz–invariance. In this case, an upper bound for the parameters is established as well.

Gamma-Ray Bursts at TeV Energies: Theoretical Considerations

Gamma-ray bursts (GRBs) are the most luminous explosions in the Universe and are powered by ultra-relativistic jets. Their prompt γ-ray emission briefly outshines the rest of the γ-ray sky, making them detectable from cosmological distances. A burst is followed by, and sometimes partially overlaps with, a similarly energetic but very broadband and longer-lasting afterglow emission. While most GRBs are detected below a few MeV, over 100 have been detected at high (≳0.1 GeV) energies, and several have now been observed up to tens of GeV with the Fermi Large Area Telescope (LAT). A new electromagnetic window in the very-high-energy (VHE) domain (≳0.1 TeV) was recently opened with the detection of an afterglow emission in the (0.1–1)TeV energy band by ground-based imaging atmospheric Cherenkov telescopes. The emission mechanism for the VHE spectral component is not fully understood, and its detection offers important constraints for GRB physics. This review provides a brief overview of the different leptonic and hadronic mechanisms capable of producing a VHE emission in GRBs. The same mechanisms possibly give rise to the high-energy spectral component seen during the prompt emission of many Fermi-LAT GRBs. Possible origins of its delayed onset and long duration well into the afterglow phase, with implications for the emission region and relativistic collisionless shock physics, are discussed. Key results for using GRBs as ideal probes for constraining models of extra-galactic background light and intergalactic magnetic fields, as well as for testing Lorentz invariance violation, are presented.

Testing Lorentz invariance of electrons with LHAASO observations of PeV gamma-rays from the Crab Nebula

The Large High Altitude Air Shower Observatory (LHAASO) recently reported the detection of gamma-ray emissions with energies up to 1.1PeV from the Crab Nebula. Using the absence of vacuum Cherenkov effect by inverse-Compton electrons, we improve previous bounds to linear-order Lorentz invariance violation (LV) in the dispersion relations of electrons by 104 times. We show that the LV effect on electrons is severely constrained, compatible with certain type of LV as expected by some models of quantum gravity (QG), such as the string/D-brane inspired space-time foam. We argue that such models are supported by the Crab Nebula constraints from the LHAASO observations, as well as various LV phenomenologies for photons to date.

Special relativity optical cavity experiments explained from the perspective of the rotating frame

In this paper, we present an explanation of a fundamental test of special relativity from the perspective of the frame co-moving with a rotating observer. The test in cause is based on the frequency comparison between two optical resonating cavities. The solution is of great interest for real-time applications because certain experiments, such as the optical resonator tests of Lorentz invariance, rely on rotating setups. We present the derivation of the optical resonator experiments from the perspective of the rotating device as compared to the inertial device. We explain the improved tests that use two rotating resonators mounted on the same substrate.

Test of Lorentz invariance using rotating ultra-stable optical cavities

We develop a rotating-optical-cavity apparatus to test Lorentz invariance in the photon sector of standard model extension. The system adopts a precision air-bearing turntable on which two 1064-nm lasers are referenced to two orthogonal 10-cm optical cavities embedded in a single block of glass. The heterodyne beat frequency of the two locked lasers is probed as the table rotates, and valid data of 119 days are accumulated. By fitting the data to the predication of the test model, eight Lorentz violating parameters (β⊕κo+XY, β⊕κo+XZ, β⊕κo+YZ, κe-ZZ, κe-XX-YY, κe-XY, κe-XZ, κe-YZ) are constrained with precision at the level of 10−17. Uncertainties of the experimental values of five κe- parameter show a 1/t decreasing trend with the measurement time. Influences of systematic effects on the test accuracy are investigated. The system is planned to run for more than one year, allowing for improved precision.

Local Lorentz Invariance Tests for Photons and Hadrons at the Gamma Factory

AbstractHigh‐precision tests of local Lorentz invariance, via monitoring of the sidereal time variation of the photon energies emitted by ultrarelativistic heavy‐ion beams and of the beam momentum, are proposed. This paper includes descriptions of the physics ideas and the concept for the detector. The experiment results will allow high‐precision tests of LLI via anisotropy of the maximum attainable speed of a photon and an ion. The projected accuracy for the asymmetries interpreted in the framework of the anisotropic relativistic mechanics corresponds to the limit on sidereal time variation of the one‐way maximum attainable speed at the levels between 10−14 and 10−17.

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

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.

Limiting superluminal neutrino velocity and Lorentz invariance violation by neutrino emission from the blazar TXS 0506+056

The detection of high-energy neutrino coincident with the blazar TXS 0506+056 provides a unique opportunity to test Lorentz invariance violation (LIV) in the neutrino sector. Thanks to the precisely measured redshift, i.e., $z=0.3365$, the comoving distance of the neutrino source is determined. In this work, we obtain and discuss the constraints on the superluminal neutrino velocity $\delta_\nu$ and the LIV by considering the energy loss of superluminal neutrino during propagation. Given superluminal electron velocity ($\delta_e \ge 0$), a very stringent constraint on superluminal neutrino velocity can be reached, i.e., $\delta_\nu \lesssim 1.3\times 10^{-18}$, corresponding to the quantum gravity (QG) scale $M_{\rm QG,1} \gtrsim 5.7 \times 10^{3} M_{\rm Pl}$ and $M_{\rm QG,2} \gtrsim 9.3 \times 10^{-6} M_{\rm Pl}$ for linear (quadratic) LIV, which are $\sim 12$ orders of magnitude tighter for linear LIV and $\sim 9$ orders tighter for quadratic LIV compared to the time-of-flight constraint from MeV neutrinos of SN 1987A. While given the subluminal electron velocity, a weaker constraint on the superluminal neutrino velocity is obtained, i.e., $\delta_\nu \lesssim 8 \times 10^{-17}$, which is consistent with the conclusions of previous works. We also study the neutrino detection probability due to the distortion of neutrino spectral shape during propagation, which gives slightly weaker constraints than above by a factor of $\sim2$.

Method to test Lorentz invariance in electron-capture decay by measuring a neutrino recoil force

Due to hypothetical Loretz invariance violation, additional terms arise in the differential rate for neutrino radiation accompanying electron capture by polarized nuclei. These terms, as well as the parity-violating term, can be probed by measurement of a small recoil force acting on a radioactive sample. An expression for this force is obtained for the case of allowed Gamow–Teller transitions. We discuss prospects to measure the force by using the methods of the magnetic resonance force microscopy, present a list of the most suitable isotopes and give the numerical estimates for mass and activity of required radioactive samples.

Relativistic Astronomy. III. Test of Special Relativity via Doppler Effect

Abstract The “Breakthrough Starshot” program is planning to send transrelativistic probes to travel to nearby stellar systems within decades. Because the probe velocity is designed to be a good fraction of the light speed, Zhang & Li recently proposed that these transrelativistic probes can be used to study astronomical objects and to test special relativity. In this work, we propose some methods to test special relativity and constrain photon mass using the Doppler effect with the images and spectral features of astronomical objects as observed in the transrelativistic probes. We introduce more general theories to set up the framework of testing special relativity, including the parametric general Doppler effect and the Doppler effect with massive photons. We find that by comparing the spectra of a certain astronomical object, one can test Lorentz invariance and constrain photon mass. Additionally, using the imaging and spectrograph capabilities of transrelativistic probes, one can test time dilation and constrain photon mass. For a transrelativistic probe with velocity v ∼ 0.2c, aperture D ∼ 3.5 cm, and spectral resolution R ∼ 100 (or 1000), we find that the probe velocity uncertainty can be constrained to σ v ∼ 0.01c (or 0.001c), and the time dilation factor uncertainty can be constrained to (or 0.001), where is the time dilation factor and γ is the Lorentz factor. Meanwhile, the photon mass limit is set to m γ ≲ 10−33 g, which is slightly lower than the energy of the optical photon.

Gravitational searches for Lorentz violation with ultracold neutrons

We investigate the consequences of Lorentz violation (as expressed within the gravity sector of the Standard-Model Extension) for gravitational quantum states of ultracold neutrons (UCNs). Since our main aim is to compare our theoretical results with the recent high-sensitivity GRANIT experiment, we frame this work according to the laboratory conditions under which it was carried out. This offers the possibility of testing Lorentz invariance by experiments using UCNs. Thus we consider the nonrelativistic Hamiltonian describing the quantum mechanics of an unpolarized neutron's beam in presence of a weak-gravity field, and the latter is described by a post-Newtonian expansion of the metric up to order $O (2)$ and linear in the Lorentz-violating coefficients $\bar{s} ^{\mu \nu}$. Using a semi-classical wave packet, which is appropriate to describe an intense beam of UCNs, we derive the effective Hamiltonian describing the neutron's motion along the axis of free fall and then we compute the Lorentz-violating shifts on the energy levels. The comparison of our results with those obtained in the GRANIT experiment leads to an upper bound for a particular combination of the Lorentz-violating coefficients.

Astroparticle Physics with H.E.S.S.: recents results and nearfuture prospects

H.E.S.S. is an array of five Imaging Atmospheric Cherenkov Telescopes located in Namibia. It is designed for observations of astrophysical sources emitting very-high-energy (VHE) gamma rays in the energy range from a few ten GeVs to several ten TeVs. The H.E.S.S. instrument consists of four identical 12 m diameter telescopes and a 28 m diameter telescope placed at the center of the array. An ambitious Astroparticle Physics program is being carried out by the H.E.S.S. collaboration searching for New Physics in the VHE gamma-ray sky. The program includes the search for WIMP dark matter and axion-like particles, tests of Lorentz invariance, cosmic-ray electron measurements, and search for intergalactic magnetic fields. I will present the latest results on dark matter search from the observations of the Galactic Centre region, the search for Lorentz invariance violation with the 2014 flare observation of Markarian 501, and the first measurement of the cosmic-ray electron spectrum up to 20 TeV. The future of the H.E.S.S. Astroparticle Physics program will be discussed.

Tests of Lorentz invariance at the Sudbury Neutrino Observatory

Experimental tests of Lorentz symmetry in systems of all types are critical for ensuring that the basic assumptions of physics are well-founded. Data from all phases of the Sudbury Neutrino Observatory, a kiloton-scale heavy water Cherenkov detector, are analyzed for possible violations of Lorentz symmetry in the neutrino sector. Such violations would appear as one of eight possible signal types in the detector: six seasonal variations in the solar electron neutrino survival probability differing in energy and time dependence, and two shape changes to the oscillated solar neutrino energy spectrum. No evidence for such signals is observed, and limits on the size of such effects are established in the framework of the Standard Model Extension, including 40 limits on perviously unconstrained operators and improved limits on 15 additional operators. This makes limits on all minimal, Dirac-type Lorentz violating operators in the neutrino sector available for the first time.

A two-axis tilt control system on a turntable for rotating-optical-cavity experiments.

Many precision measurements using rotating optical cavities have tight requirement on the level of a rotating platform on which the cavities are installed. We develop a single-stage tilt control system as one part of the experimental setup for testing Lorentz invariance using two optical cavities that are perpendicular to each other. Home built voice-coil actuators, together with a tilt sensor and control electronics, are adopted to simultaneously suppress the tilt of the rotating platform in two orthogonal directions. The large cross coupling between two orthogonal axes is observed, and its mechanism is examined. By adding a compensating weight, the loop instability resulting from the cross coupling is effectively removed. With the active control, the variation of the tilt around each of the two axes is reduced from the free-running value of ±30 µrad to within ±0.2 µrad, independently measured by using a second tilt sensor. This residual tilt has a component at the rotational frequency with an amplitude of 0.1 µrad, which contributes a systematical offset of 1.8 × 10-17 to the Lorentz violating parameter κ e- ZZ, estimated by assuming that the tilt sensitivity of the optical cavity is 1 × 10-16/μrad. Further improvement is still possible by using piezo-electric actuators that exhibit higher resonant frequencies, a different approach that will suppress the residual variation of the tilt to within ±0.01 µrad and allow a reduced systematical offset of 1.8 × 10-18 for κ e- ZZ.

BOOST: A satellite mission to test Lorentz invariance using high-performance optical frequency references

BOOST (BOOst Symmetry Test) is a proposed satellite mission to search for violations of Lorentz invariance by comparing two optical frequency references. One is based on a long-term stable optical resonator, and the other is based on a hyperfine transition in molecular iodine. This mission will allow us to determine several parameters of the standard model extension in the electron sector up to 2 orders of magnitude better than with the current best experiments. Here, we will give an overview of the mission, the science case, and the payload.

Next Generation of Phonon Tests of Lorentz Invariance Using Quartz BAW Resonators.

We demonstrate technological improvements in phonon sector tests of the Lorentz invariance that implement quartz bulk acoustic wave oscillators. In this experiment, room temperature oscillators with state-of-the-art phase noise are continuously compared on a platform that rotates at a rate of order of a cycle per second. The discussion is focused on improvements in noise measurement techniques, data acquisition, and data processing. Preliminary results of the second generation of such tests are given, and indicate that standard model extension coefficients in the matter sector can be measured at a precision of order 10-16 GeV after taking a year's worth of data. This is equivalent to an improvement of two orders of magnitude over the prior acoustic phonon sector experiment.

New Methods for Testing Lorentz Invariance with Atomic Systems.

We describe a broadly applicable experimental proposal to search for the violation of local Lorentz invariance (LLI) with atomic systems. The new scheme uses dynamic decoupling and can be implemented in current atomic clock experiments, with both single ions and arrays of neutral atoms. Moreover, the scheme can be performed on systems with no optical transitions, and therefore it is also applicable to highly charged ions which exhibit a particularly high sensitivity to Lorentz invariance violation. We show the results of an experiment measuring the expected signal of this proposal using a two-ion crystal of ^{88}Sr^{+} ions. We also carry out a systematic study of the sensitivity of highly charged ions to LLI to identify the best candidates for the LLI tests.