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Based on the recent association of IceCube TeV and PeV neutrino events with gamma-ray bursts (GRBs) by considering the Lorentz violation of neutrinos, we provide a new estimate on the ...GRB neutrino flux with a more significant result compared to the previous constraint by the IceCube Collaboration. Among these 24 neutrino “shower” events above 60 TeV, 12 events are associated with GRBs. Such a result is compatible with the prediction from GRB fireball models. Analysis of track events provides a consistent result with the shower events to associate high energy cosmic neutrinos with GRBs under the same Lorentz violation features of neutrinos. We also make a background estimation and reveal GRBs as a significant source for the ultra-high energy IceCube neutrino events. Our work supports the Lorentz violation and CPT-violation of neutrinos, indicating new physics beyond relativity.
In this work, we review the effective field theory framework to search for Lorentz and CPT symmetry breaking during the propagation of gravitational waves. The article is written so as to bridge the ...gap between the theory of spacetime-symmetry breaking and the analysis of gravitational-wave signals detected by ground-based interferometers. The primary physical effects beyond General Relativity that we explore here are dispersion and birefringence of gravitational waves. We discuss their implementation in the open-source LIGO-Virgo algorithm library suite, and we discuss the statistical method used to perform a Bayesian inference of the posterior probability of the coefficients for symmetry-breaking. We present preliminary results of this work in the form of simulations of modified gravitational waveforms, together with sensitivity studies of the measurements of the coefficients for Lorentz and CPT violation. The findings show the high potential of gravitational wave sources across the sky to sensitively probe for these signals of new physics.
A deformation of special relativistic kinematics (possible signal of a theory of quantum gravity at low energies) leads to a modification of the notion of spacetime. At the classical level, this ...modification is required when one considers a model including single- or multi-interaction processes, for which absolute locality in terms of canonical spacetime coordinates is lost. We discuss the different alternatives for observable effects in the propagation of a particle over very large distances that emerge from the new notion of spacetime. A central ingredient in the discussion is the cluster decomposition principle, which can be used to favor some alternatives over the others.
It is plausible that quantum gravity effects may lead us to a description of Nature beyond the framework of special relativity. In this case, either the relativity principle is broken or it is ...maintained. These two scenarios (a violation or a deformation of special relativity) are very different, both conceptually and phenomenologically. We discuss some of their implications on the description of events for different observers and the notion of spacetime.
We explore the possibility to geometrize the interaction of massive fermions with the quantum structure of space–time, trying to create a theoretical background, in order to explain what some recent ...experimental results seem to implicate on the propagation of Ultra High Energy Cosmic Rays (UHECR). We will investigate part of the phenomenological implications of this approach on the predicted effect of the UHECR suppression, in fact recent evidences seem to involve the modification of the GZK cut-off phenomenon. The search for an effective theory, which can explain this physical effect, is based on Lorentz Invariance Violation (LIV), which is introduced via Modified Dispersion Relations (MDRs). Furthermore we illustrate that this perspective implies a more general geometry of space–time than the usual Riemannian one, indicating, for example, the opportunity to resort to Finsler theory.
X-ray polarimetry promises to give qualitatively new information about high-energy sources. Examples of interesting source classes are binary black hole systems, rotation and accretion powered ...neutron stars, microquasars, active galactic nuclei and gamma-ray bursts. Furthermore, X-ray polarimetry affords the possibility for testing fundamental physics, e.g. to observe signatures of light bending in the strong gravitational field of a black hole, to detect third order quantum electrodynamic effects in the magnetosphere of magnetars, and to perform sensitive tests of Lorentz invariance. In this paper we discuss scientific drivers of hard (>10
keV) X-ray polarimetry emphasizing how observations in the hard band can complement observations at lower energies (0.1–10
keV). Subsequently, we describe four different technical realizations of hard X-ray polarimeters suitable for small to medium sized space borne missions, and study their performance in the signal-dominated case based on Monte Carlo simulations. We end with confronting the instrument requirements for accomplishing the science goals with the capabilities of the four polarimeters.
► For the first time, GRB models are used to consider possible LIV effects in GRBs. ► Both intrinsic time lags and possible LIV induced time lags are considered. ► The constraints of LIV effects can ...be unified for both long and short bursts.
Possible Lorentz invariance violation (LIV) has been investigated for a long time based on observations of GRBs. These arguments relied on the assumption that photons with different energy are emitted at the same place and time. In this work, we try to take account of the intrinsic time delay Δtint between emissions of low and high energy photons by using the magnetic jet model. The possible LIV effects are discussed in a unified scenario both for long and short Fermi-detected GRBs. This leads to a unique quantum gravity energy scale M1c2∼1.0×1020GeV respecting the linear dispersion relation.
High energy photons from astrophysical sources are unique probes for some predictions of candidate theories of Quantum Gravity (QG). In particular, Imaging atmospheric Cherenkov telescope (IACTs) are ...instruments optimised for astronomical observations in the energy range spanning from a few tens of GeV to ∼100 TeV, which makes them excellent instruments to search for effects of QG. In this article, we will review QG effects which can be tested with IACTs, most notably the Lorentz invariance violation (LIV) and its consequences. It is often represented and modelled with photon dispersion relation modified by introducing energy-dependent terms. We will describe the analysis methods employed in the different studies, allowing for careful discussion and comparison of the results obtained with IACTs for more than two decades. Loosely following historical development of the field, we will observe how the analysis methods were refined and improved over time, and analyse why some studies were more sensitive than others. Finally, we will discuss the future of the field, presenting ideas for improving the analysis sensitivity and directions in which the research could develop.
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