scholarly journals Gauge invariant electromagnetic properties of fermions induced by CPT-violation in the Standard Model Extension

2014 ◽  
Vol 29 (08) ◽  
pp. 1450039 ◽  
Author(s):  
A. Moyotl ◽  
H. Novales-Sanchez ◽  
J. J. Toscano ◽  
E. S. Tututi
Keyword(s):  
Quantum Electrodynamics ◽  
Lorentz Invariance ◽  
Lorentz Violation ◽  
Second Order ◽  
Low Energy ◽  
Electromagnetic Properties ◽  
Tree Level ◽  
Standard Model Extension ◽  
Gauge Invariant ◽  
The One

Low-energy Lorentz-invariant quantities could receive contributions from a fundamental theory producing small Lorentz-violating effects. Within the Lorentz-violating extension of quantum electrodynamics, we investigate, perturbatively, the contributions to the one-loop ffγ vertex from the CPT-violating axial coupling of a vector background field to fermions. We find that the resulting vertex function has a larger set of Lorentz structures than the one characterizing the usual, Lorentz-invariant, parametrization of the ffγ vertex. We prove gauge invariance of the resulting one-loop expression through a set of gauge invariant nonrenormalizable operators introducing new-physics effects at the first- and second-orders in Lorentz-violation, and which generate tree-level contributions to the ffγ vertex. Whereas loop contributions involving parameters that violate Lorentz-invariance at the first-order are CPT-odd, those arising at the second-order are CPT-even, so that contributions to low-energy physics are restricted to emerge for the first time at the second-order. In this context, we derive a contribution to anomalous magnetic moment (AMM) of fermions, which we use to set a bound on Lorentz-violation.

scholarly journals One-loop nonbirefringent effects on the electromagnetic vertex in the Standard Model Extension

2014 ◽  
Vol 29 (22) ◽  
pp. 1450107 ◽  
Author(s):  
A. Moyotl ◽  
H. Novales-Sanchez ◽  
J. J. Toscano ◽  
E. S. Tututi
Keyword(s):  
Standard Model ◽  
Lorentz Invariance ◽  
Lorentz Violation ◽  
Tree Level ◽  
Isotropic Case ◽  
Photon Propagator ◽  
Standard Model Extension ◽  
Model Extension ◽  
The One ◽  
Electromagnetic Vertex

Lorentz violation emerged from a fundamental description of nature may impact, at low energies, the Maxwell sector, so that contributions from such new physics to the electromagnetic vertex would be induced. Particularly, nonbirefringent CPT-even effects from the electromagnetic sector modified by the Lorentz- and CPT-violating Standard Model Extension alter the structure of the free photon propagator. We calculate Lorentz-violating contributions to the electromagnetic vertex, at the one-loop level, by using a modified photon propagator carrying this sort of effects. We take the photon off shell, and find an expression that involves both isotropic and anisotropic effects of nonbirefringent violation of Lorentz invariance. Our analysis of the one-loop vertex function includes gauge invariance, transformation properties under C, P and T, and tree-level contributions from Lorentz-violating nonrenormalizable interactions. These elements add to previous studies of the one-loop contributions to the electromagnetic vertex in the context of Lorentz violation in the photon sector. Finally, we restrict our analysis to the isotropic case and derive a finite contribution from isotropic Lorentz violation to the anomalous magnetic moment of fermions that coincides with the result already reported in the literature.

scholarly journals Photon splitting bound on Lorentz Violation in QED from multi-TeV photon observation.

2018 ◽  
Vol 191 ◽  
pp. 02020
Author(s):  
Konstantin Astapov ◽  
Petr Satunin ◽  
Dmitry Kirpichnikov
Keyword(s):  
Quantum Electrodynamics ◽  
Crab Nebula ◽  
Lorentz Invariance ◽  
Lorentz Violation ◽  
Mass Scale ◽  
Special Model ◽  
Astrophysical Source ◽  
Broken Lorentz Invariance ◽  
Photon Splitting ◽  
The Crab Nebula

We calculate the width of photon splitting to three photons in a special model of quantum electrodynamics with broken Lorentz invariance. This process may lead to a sharp cut-off in a photon spectrum of a given astrophysical source. Analysing experimental data, we set a constraint on Lorentz-violating mass scale from the absence of such cut-off in the Crab Nebula spectrum.

scholarly journals TESTS OF LORENTZ AND CPT VIOLATION WITH MiniBooNE NEUTRINO OSCILLATION EXCESSES

2012 ◽  
Vol 27 (25) ◽  
pp. 1230024 ◽  
Author(s):  
TEPPEI KATORI
Keyword(s):  
Standard Model ◽  
Neutrino Oscillation ◽  
Lorentz Invariance ◽  
Planck Scale ◽  
Lorentz Violation ◽  
New Physics ◽  
Cpt Symmetry ◽  
Standard Model Extension ◽  
Sidereal Time ◽  
Short Baseline

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 (νSM); 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 Lorentz invariance in neutrinos. In this brief review, we introduce Lorentz violation, the neutrino sector of the SME and the analysis of short-baseline neutrino oscillation experiments. We then present the results of the search for Lorentz violation in MiniBooNE data. This review is based on the published result.

scholarly journals LORENTZ VIOLATION DISPERSION RELATION AND ITS APPLICATION

2009 ◽  
Vol 24 (07) ◽  
pp. 1359-1381 ◽  
Author(s):  
ZHI XIAO ◽  
BO-QIANG MA
Keyword(s):  
Dispersion Relation ◽  
Quantum Electrodynamics ◽  
Lorentz Violation ◽  
Cosmic Ray ◽  
Ultrahigh Energy ◽  
Standard Model Extension ◽  
Modified Dispersion Relation ◽  
Model Extension ◽  
The Standard Model ◽  
Spinor Formalism

We derive a modified dispersion relation (MDR) in the Lorentz violation extension of the 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 to spin–gravity coupling. We also develop a neutrino oscillation mechanism induced by the presence of nondiagonal terms of Lorentz violation couplings in two-flavor space in a two-spinor formalism by explicitly assuming neutrinos to be Marjorana fermions. We also obtain a very stringent bound (∽ 10-25) on one of the Lorentz violation parameters by applying the MDR to the ultrahigh energy cosmic ray (UHECR) problem.

scholarly journals Tests of Lorentz Symmetry in Single Beta Decay

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Jorge S. Díaz
Keyword(s):  
Beta Decay ◽  
Neutrino Oscillations ◽  
Lorentz Invariance ◽  
Lorentz Violation ◽  
Lorentz Symmetry ◽  
Low Energy ◽  
Spacetime Symmetry

Low-energy experiments studying single beta decay can serve as sensitive probes of Lorentz invariance that can complement interferometric searches for deviations from this spacetime symmetry. Experimental signatures of a dimension-three operator for Lorentz violation which are unobservable in neutrino oscillations are described for the decay of polarized and unpolarized neutrons as well as for measurements of the spectral endpoint in beta decay.

scholarly journals (Gravitational) Vacuum Cherenkov Radiation

Symmetry ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 424 ◽  
Author(s):  
Marco Schreck
Keyword(s):  
Cherenkov Radiation ◽  
Lorentz Invariance ◽  
Lorentz Violation ◽  
Minkowski Spacetime ◽  
Standard Model Extension ◽  
Essential Properties ◽  
Model Extension ◽  
The Standard Model ◽  
Gravitational Vacuum ◽  
The Common

This work reviews our current understanding of Cherenkov-type processes in vacuum that may occur due to a possible violation of Lorentz invariance. The description of Lorentz violation is based on the Standard Model Extension (SME). To get an overview as general as possible, the most important findings for vacuum Cherenkov radiation in Minkowski spacetime are discussed. After doing so, special emphasis is put on gravitational Cherenkov radiation. For a better understanding, the essential properties of the gravitational SME are recalled in this context. The common grounds and differences of vacuum Cherenkov radiation in Minkowski spacetime and in the gravity sector are emphasized.

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 Implications of SU(2)L gauge invariance for constraints on Lorentz violation

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Andreas Crivellin ◽  
Fiona Kirk ◽  
Marco Schreck
Keyword(s):  
Charged Lepton ◽  
Gamma Ray ◽  
Lorentz Invariance ◽  
Lorentz Violation ◽  
Lepton Sector ◽  
Standard Model Extension ◽  
Neutrino Sector ◽  
Model Extension ◽  
Charged Leptons ◽  
Charged Lepton Sector

Abstract Lorentz invariance may only be broken far above the electroweak scale, since violations are experimentally stringently constrained. Therefore, the Standard-Model Extension parameterizing Lorentz violation (LV) via (higher-dimensional) field theory operators is manifestly SU(2)L gauge-invariant. As a consequence, LV in neutrinos implies LV in charged leptons and vice versa. This allows us to obtain estimated sensitivities for flavour-changing operators in the charged-lepton sector from neutrino oscillations as well as sensitivities for flavour-diagonal neutrino effects from high-precision electron experiments. We also apply this method to an analysis of time-of-flight data for neutrinos (detected by IceCube) and photons from gamma ray bursts where discrepancies have been observed. Our conclusion is that an explanation of the arrival time difference between neutrino and photon events by dim-5 operators in the neutrino sector would lead to unacceptably large LV effects in the charged-lepton sector.

scholarly journals Decays Z → γγ and Z → gg in the Standard Model Extension

2015 ◽  
Vol 30 (35) ◽  
pp. 1550216 ◽  
Author(s):  
J. Castro-Medina ◽  
H. Novales-Sanchez ◽  
J. J. Toscano ◽  
E. S. Tututi
Keyword(s):  
Standard Model ◽  
Background Field ◽  
Standard Model Extension ◽  
Gauge Invariant ◽  
Spatial Component ◽  
Loop Level ◽  
Model Extension ◽  
The Standard Model ◽  
Decay Widths ◽  
The One

The [Formula: see text] and [Formula: see text] decays are studied in the context of the renormalizable version of the Standard Model Extension. The [Formula: see text]-odd [Formula: see text] bilinear interaction, which involves the constant background field [Formula: see text] and which has been a subject of interest in literature, is considered. It is shown that the [Formula: see text] and [Formula: see text] decays, which are strictly zero in the standard model, can be generated radiatively at the one-loop level. It is found that these decays are gauge invariant and free of ultraviolet divergences, and that the corresponding decay widths only depend on the spatial component of the background field [Formula: see text].

scholarly journals NLO electroweak potentials for minimal dark matter and beyond

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Kai Urban
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Low Energy ◽  
Tree Level ◽  
Static Potential ◽  
Position Space ◽  
Gauge Bosons ◽  
Loop Correction ◽  
The One ◽  
Energy Property

Abstract We calculate the one-loop correction to the static potential induced by γ, W and Z-exchange at tree-level for arbitrary heavy standard model multiplets. We find that the result obeys a “Casimir-like” scaling, making the NLO correction to the potential a “low-energy” property of the electroweak gauge bosons. Furthermore, we discuss the phenomenology of the NLO potentials, the analytically known asymptotic limits and provide fitting functions in position space for easy use of the results.

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