We investigate the prospects for detecting violations of Lorentz symmetry in unpolarized deep inelastic electron-proton scattering in the context of the future electron-ion collider. Simulated differential cross-section data are used to place expected bounds on a class of quark-sector coefficients for Lorentz violation that induce sidereal time dependence in the scattering cross section. We find that, with $100 \; {\rm fb}^{-1}$ of integrated luminosity, the expected bounds are in the $10^{-5}-10^{-7}$ range and are roughly two orders of magnitude stronger than those that can be extracted from existing HERA data. We also discuss the possibility of extracting bounds on the remaining time-independent coefficients.
Tests of Lorentz invariance violation and CPT Violation in neutrino oscillations are discussed. The sensitivity of current and future experiments is presented.
Violations of Lorentz symmetry are typically associated with modifications of one-particle dispersion relations. The physical effects of such modifications in particle collisions often grow with energy, so that ultrahigh-energy cosmic rays provide an excellent laboratory for measuring such effects. In this talk we argue that collisions at particle colliders, which involve much smaller energies, can nevertheless yield competitive constraints on Lorentz breaking.
Violation of Lorentz invariance and CPT symmetry is a predicted phenomenon of Planck-scale physics. Various types of data are analyzed to search for Lorentz violation under the Standard-Model Extension (SME) framework, including neutrino oscillation data. MiniBooNE is a short-baseline neutrino oscillation experiment at Fermilab. The measured excesses from MiniBooNE cannot be reconciled within the neutrino Standard Model; thus it might be a signal of new physics, such as Lorentz violation. We have analyzed the sidereal time dependence of MiniBooNE data for signals of the possible breakdown of L…
Searches for Lorentz and CPT violation using neutrino oscillations and the prospects for future tests using neutrino time-of-flight measurements and beta-decay experiments are presented.
Neutrino oscillations provide an opportunity for sensitive tests of Lorentz invariance. This talk reviews some aspects of Lorentz violation in neutrinos and the prospect of testing Lorentz invariance in neutrino-oscillation experiments. A general Lorentz-violating theory for neutrinos is discussed, and some signals of Lorentz violation are identified.
We point out that equivalence principle violations, while not dynamically equivalent, produce the same kinematical effects as Lorentz invariance violations for particle processes in a constant gravitational potential. This allows us to translate many experimental bounds on Lorentz invariance violations into bounds on equivalence principle violations. The most stringent bound suggests that a postive signal in an Eötvös experiment may be at least seven orders of magnitude beyond current technology.
A search for sidereal variations in the force between two planar tungsten oscillators separated by about 80 microns sets the first experimental limits on Lorentz violation involving quadratic couplings of the Riemann curvature, consistent with no effect at the level of $10^{-7}$ m$^2$.
This talk outlines some results for gravitational theories with local Lorentz violation in the context of the Lorentz- and CPT-violating Standard-Model Extension.
Lorentz violation naturally leads to neutrino oscillations and provides an alternative mechanism that may explain current data. In this work, we discuss possible signals of Lorentz violation in neutrino-oscillation experiments.
Spectropolarimetry of distant sources of electromagnetic radiation at wavelengths ranging from infrared to ultraviolet are used to constrain Lorentz violation. A bound of 3x10^{-32} is placed on coefficients for Lorentz violation.
Motivated by a recent and several earlier measurement results of the neutrino velocity, we attempt to resolve the apparent discrepancies between them from the viewpoint of mass-energy relation in special relativity. It is argued that a complicated tachyonic neutrino model or a mass-dependent Lorentz violation theory can do this job.
Vacuum birefringence is a signature of Lorentz-symmetry violation. Here we report on a recent search for birefringence in the cosmic microwave background. Polarization data is used to place constraints on certain forms of Lorentz violation.
In a model with Lorentz invariance violation implemented through modified dispersion relations, we estimate the rate for the decay process gamma -> 3 gamma and find that it provides a relevant bound on Lorentz invariance violation.
Solar-neutrino oscillations are considered using a massive model with perturbative Lorentz violation. The adiabatic approximation is used to calculate the effects of Lorentz violation to leading order. The results are more compact than previous work involving vacuum oscillations, and are accurate for small Lorentz-violating coefficients.
Relating the effective Lorentz violation coefficients for composite particles to the coefficients for their constituent fields is a challenging problem. We calculate the Lorentz violation coefficients relevant to the dynamics of an alpha-particle in terms of proton and neutron coefficients. The alpha-particle coefficients would lead to anisotropies in the alpha-decays of nuclei, and because the decay process involves quantum tunneling, the effects of any Lorentz violations could be exponentially enhanced.
Existing experimental data for neutrino oscillations are consistent with Lorentz-violating massless neutrinos. This talk summarizes some aspects of neutrino oscillations from the perspective of Lorentz and CPT violation in effective quantum field theory.
This presentation discusses some of the signals for Lorentz violation potentially observable in atomic spectroscopy and clock-comparison experiments. The emphasis of the discussion is on how the angular-momentum quantum numbers of the states involved in the transition determine the properties of the possible sidereal variation of the transition frequency.
This article presents prospects for Lorentz-violation searches with $t\bar{t}$ at the LHC and future colliders. After a short presentation of the Standard-Model Extension as a Lorentz-symmetry-breaking effective field theory, we will focus on $t\bar{t}$ production. We study the impact of Lorentz violation as a function of center-of-mass energy and evaluate the sensitivity of collider experiments to this signal.
This talk provides a status report on CPT violation in neutral-meson oscillations, focusing on implications of the CPT- and Lorentz-violating standard-model extension.
A general introduction to Lorentz and CPT violation is presented. The observable effects of the breakdown of such fundamental symmetries in neutrinos are outlined and different experimental searches of some of the key signals of Lorentz violation are discussed. A novel powerful method to study model-independent neutrino oscillations is reviewed and then used to illustrate a new global model of neutrino oscillations based on Lorentz violation consistent with atmospheric, accelerator, reactor, and solar neutrino data.
Broken spacetime symmetries might emerge from a fundamental physical theory. The effective low-energy theory might be expected to exhibit violations of supersymmetry and Lorentz invariance. Some illustrative models which combine supersymmetry and Lorentz violation are described, and a superspace formulation is given.
The effects of quark-sector Lorentz violation on deep inelastic electron-proton scattering are studied. We show that existing data can be used to establish first constraints on numerous coefficients for Lorentz violation in the quark sector at an estimated sensitivity of parts in a million.
Lorentz-violating extensions of the Wess-Zumino model have been formulated in superspace. The models respect a supersymmetry algebra and can be understood as arising from suitably modified superspace transformations.
Electromagnetic resonant cavities form the basis for a number modern tests of Lorentz invariance. The geometry of most of these experiments implies unsuppressed sensitivities to parity-even Lorentz violations only. Parity-odd violations typically enter through suppressed boost effects, causing a reduction in sensitivity by roughly four orders of magnitude. Here we discuss possible techniques for achieving unsuppressed sensitivities to parity-odd violations by using asymmetric resonators.
Electromagnetic resonant cavities form the basis of many tests of Lorentz invariance involving photons. The effects of some forms of Lorentz violation scale with cavity size. We investigate possible signals of violations in the naturally occurring resonances formed in the Earth-ionosphere cavity. Comparison with observed resonances places the first terrestrial constraints on coefficients associated with dimension-three Lorentz-violating operators at the level of 10^{-20} GeV.
The violation of Lorentz symmetry can arise in a variety of approaches to fundamental physics. For the description of the associated low-energy effects, a dynamical framework known as the Standard-Model Extension has been developed. This talk gives a brief review of the topic focusing on Lorentz violation through varying couplings.
Lorentz violation is a predicted phenomenon from the Planck scale physics. Although the three active massive neutrino framework with the Standard Model (SM), so-called the neutrino Standard Model (nuSM), is successful, series of signals not understood within the nuSM suggest neutrino physics may be the first place to see the physics beyond the SM, such as Lorentz violation. Especially, neutrino oscillations are the natural interferometer and they are sensitive to the Lorentz violation. The LSND oscillation signal was analyzed under the Standard Model Extension (SME) framework, and it was found…
Overview of spontaneous Lorentz and CPT breaking mechanism in the context of the standard model contributed to the proceedings for the Coral Gables meeting.
Space-based experiments offer sensitivity to numerous unmeasured effects involving Lorentz and CPT violation. We provide a classification of clock sensitivities and present explicit expressions for time variations arising in such experiments from nonzero coefficients in the Lorentz- and CPT-violating Standard-Model Extension.
We consider Lorentz violation in supersymmetric extensions of the standard model. We perform a spurion analysis to show that, in the simplest natural constructions, the resulting supersymmetry-breaking masses are tiny. In the process, we argue that one of the strongest bounds on Lorentz violation in the photon Lagrangian, which comes from the absence of birefringence from distant astrophysical sources, does not apply when Lorentz violation is parametrized by a single vector.
This contribution to the CPT'16 proceedings summarizes recent tests of Lorentz violation in the pure-gravity sector with cosmic rays and reviews recent progress in matter-gravity couplings.
Momentum dependence of quantum corrections with higher-dimensional Lorentz violation is examined in electrodynamics on orbifolds. It is shown that effects of the Lorentz violation are not decoupled at high energy scales. Despite the loss of the higher-dimensional Lorentz invariance, a higher-dimensional Ward identity is found to be fulfilled for one-loop vacuum polarization. This implies that gauge invariance may be prior to Lorentz invariance as a guiding principle in higher-dimensional field theory. As a universal application of electrodynamics, an extra-dimensional aspect for Furry's theore…
An overview of recent progress on testing Lorentz and CPT symmetry using Penning traps is presented. The theory of quantum electrodynamics with Lorentz-violating operators of mass dimensions up to six is summarized. Dominant shifts in the cyclotron and anomaly frequencies of the confined particles and antiparticles due to Lorentz and CPT violation are derived. Existing results of the comparisons of charge-to-mass ratios and magnetic moments involving protons, antiprotons, electrons, and positrons are used to constrain various coefficients for Lorentz violation.
The explicit one-loop renormalizability of the gluon sector of QCD with Lorentz violation is demonstrated. The result is consistent with multiplicative renormalization as the required counter terms are consistent with a single re-scaling of the Lorentz-violation parameters. In addition, the resulting beta functions indicate that the CPT-even Lorentz-violating terms increase with energy scale in opposition to the asymptotically free gauge coupling and CPT-odd terms. The calculations are performed at lowest-order in the Lorentz-violating terms as they are assumed small.
The explicit one-loop renormalizability of pure Yang-Mills theory with Lorentz violation is demonstrated. The result is consistent with multiplicative renormalization as the required counter terms are consistent with a single re-scaling of the Lorentz-violation parameters. In addition, the resulting beta functions indicate that the CPT-even Lorentz-violating terms increase with energy scale in opposition to the asymptotically free gauge coupling and CPT-odd terms. The calculations are performed at lowest-order in the Lorentz-violating terms as they are assumed small.
We derive a modified dispersion relation (MDR) in the Lorentz violation extension of quantum electrodynamics (QED) sector in the standard model extension (SME) framework. Based on the extended Dirac equation and corresponding MDR, we observe the resemblance of the Lorentz violation coupling with spin-gravity coupling. We also develop a neutrino oscillation mechanism induced by the presence of nondiagonal terms of Lorentz violation couplings in 2-flavor space in a 2-spinor formalism by explicitly assuming neutrinos to be Marjorana fermions. We also obtain a much stringent bound ($\backsim10^{-2…
In this talk, we explore the relation between smoothly varying couplings and Lorentz violation. Within the context of a supergravity model, we present an explicit mechanism that causes the effective fine-structure parameter and the effective electromagnetic $θ$ angle to acquire related spacetime dependences. We argue that this leads to potentially observable Lorentz violation and discuss some implications for the Standard-Model Extension.
This talk, given at CPT'13, showed Super-Kamiokande atmospheric-neutrino Monte Carlo sensitivity to Lorentz-violation effects using the perturbative model derived from the Standard-Model Extension.
This contribution to the CPT'16 meeting briefly highlights some of the recent progress in the phenomenology of Lorentz and CPT violation, with emphasis on research performed at the Indiana University Center for Spacetime Symmetries.
In recent years, the effects of Lorentz symmetry breaking in cosmology has attracted considerable amount of attention. In cosmological context several topics can be affected by Lorentz violation,e.g., inflationary scenario, CMB, dark energy problem and barryogenesis. In this paper we consider the cosmological particle creation due to Lorentz violation (LV). We consider an exactly solvable model for finding the spectral properties of particle creation in an expanding space-time exhibiting Lorentz violation. In this model we calculate the spectrum and its variations with respect to the rate and …
Hadron colliders are providing a unique opportunity for testing Lorentz invariance and CPT symmetry at high energy and in a laboratory. A first measurement in the top-quark sector was performed at the Tevatron. We present here prospective studies for testing Lorentz invariance in top-quark pair production at the LHC and future colliders. The b-quark sector was investigated recently at LHCb. Eventually, new bounds on photon parameters can be extracted from the observation of TeV photons at the LHC. We will conclude by highlighting other opportunities provided by hadron colliders.
We analyze Doppler-effect experiments in terms of a general framework for violations of Lorentz symmetry: the Standard-Model Extension. These experiments are found to be sensitive to heretofore unprobed combinations of Lorentz-violation coefficients associated with protons and electrons. New bounds at the level of $10^{-11}$ and $10^{-8}$ for proton coefficients and $10^{-2}$ for electron coefficients emerge from a recent experiment.
Lorentz violations in gravitational waves are investigated. Plane-wave solutions for arbitrary gauge-invariant violations in linearized gravity are constructed. Signatures of Lorentz violation include dispersion, birefringence, and anisotropies. Modifications to waves from coalescing compact binaries and to strain signals in gravitational-wave detectors are derived.
Extremely high-energy(EHE) cosmic rays might provide a chance to check a violation of the Lorentz symmetry of spacetime. Some theoretical consideration is described about why the Lorentz symmetry might break-down in EHE phenomena in this universe. Some models which introduce the violation of the Lorentz symmetry will be discussed.
Depending on deformed canonical anti-commutation relations, massless neutrino oscillation based on Lorentz invariance violation in non-commutative field theory is discussed. It is found that the previous studies about massless neutrino oscillation within deformed canonical anti-commutation relations should satisfy the condition of new Moyal product and new non standard commutation relations. Furthermore, comparing the Lorentz Invariant Violation parameters $\mathit{A}$ in the previous studies with new Moyal product and new non standard commutation relations, we find that the orders of magnitud…
This paper investigates a signature of Lorentz invariance violation with the $t\bar{t}$ production at the LHC and future hadron colliders. Possible deviations from the Lorentz symmetry remain poorly constrained in the top quark sector. With a dedicated analysis of $t\bar{t}$ events produced at the LHC, bounds in the top sector can be improved by up to three orders of magnitude relative to Tevatron, the only measurement existing so far. The sensitivity will be even further enhanced at the HL-LHC and future colliders.
Constraints from clock-comparison experiments on violations of Lorentz and CPT symmetry are investigated in the context of a general Lorentz-violating extension of the standard model. The experimental signals are shown to depend on the atomic and ionic species used as clocks. Certain experiments usually regarded as establishing comparable bounds are in this context sensitive to different types of Lorentz violation. Some considerations relevant to possible future measurements are presented. All these experiments are potentially sensitive to Lorentz-violating physics at the Planck scale.
A parton-model description of high-energy hadronic interactions in the presence of Lorentz violation is presented. This approach is used to study lepton-hadron and hadron-hadron interactions at large momentum transfer. Cross sections for deep inelastic scattering and the Drell-Yan process are calculated at first order for minimal and nonminimal Lorentz violation. Estimated bounds are placed using existing LHC and future US-based Electron-Ion Collider data.
Quantitative bounds on Lorentz symmetry violation in the neutrino sector have been obtained by analyzing existing laboratory data on neutron $β$ decay and pion leptonic decays. In particular some parameters appearing in the energy-momentum dispersion relations for $ν_e$ and $ν_μ$ have been constrained in two typical cases arising in many models accounting for Lorentz violation.
The effects of Lorentz and CPT violations on macroscopic objects are explored. Effective composite coefficients for Lorentz violation are derived in terms of coefficients for electrons, protons, and neutrons in the Standard-Model Extension, including all minimal and nonminimal violations. The hamiltonian and modified Newton's second law for a test body are derived. The framework is applied to free-fall and torsion-balance tests of the weak equivalence principle and to orbital motion. The effects on continuous media are studied, and the frequency shifts in acoustic resonators are calculated.
Pions, like nucleons, are composed primarily of up and down quarks and gluons. Constraints on spin-independent Lorentz violation in the proton, neutron, and pion sectors translate into bounds on Lorentz violation for the fundamental fields. The best bounds on pion Lorentz violation come from astrophysical measurements. The absence of the absorption process gamma --> pi^(+) + pi^(-) for up to 50 TeV photons constrains the possibility that pions' maximum achievable velocities are less than 1 at the 1.5 x 10^(-11) level. The fact that pions with energies up to 30 TeV are observed to decay into ph…
We have examined Lorentz invariance and equivalence principle violations in the neutrino sector as manifested in neutrinoless double beta decay. We conclude that this rare decay cannot provide a useful view of these exotic processes.
Neutrino oscillations in the presence of Lorentz violation can present novel observable signals in both long- and short-baseline experiments. In this talk we describe the theory and its different regimes depending on properties of the experiments. CPT violation, its systematic search and possible connections to latest results are also presented.
A framework is presented for the factorization of high-energy hadronic processes in the presence of Lorentz and CPT violation. The comprehensive effective field theory describing Lorentz and CPT violation, the Standard-Model Extension, is used to demonstrate factorization of the hadronic tensor at leading order in electroweak interactions for deep inelastic scattering and for the Drell-Yan process. Effects controlled by both minimal and nonminimal coefficients for Lorentz violation are explored, and the equivalent parton-model description is derived. The methodology is illustrated by determini…
A general discussion is given of signals for broken Lorentz symmetry in short-baseline neutrino experiments. Among the effects that Lorentz violation can introduce are a dependence on energy differing from that of the usual massive-neutrino solution and a dependence on the direction of neutrino propagation. Using the results of the LSND experiment, explicit analysis of the effects of broken Lorentz symmetry yields a nonzero value (3+/-1) x 10^{-19} GeV for a combination of coefficients for Lorentz violation. This lies in the range expected for effects originating from the Planck scale in an un…
