scholarly journals Quantum Gravity Phenomenology Induced in the Propagation of UHECR, a Kinematical Solution in Finsler and Generalized Finsler Spacetime

Galaxies ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 103
Author(s):  
Marco Danilo Claudio Torri

It is well-known that the universe is opaque to the propagation of Ultra-High-Energy Cosmic Rays (UHECRs) since these particles dissipate energy during their propagation interacting with the background fields present in the universe, mainly with the Cosmic Microwave Background (CMB) in the so-called GZK cut-off phenomenon. Some experimental evidence seems to hint at the possibility of a dilation of the GZK predicted opacity sphere. It is well-known that kinematical perturbations caused by supposed quantum gravity (QG) effects can modify the foreseen GZK opacity horizon. The introduction of Lorentz Invariance Violation can indeed reduce, and in some cases making negligible, the CMB-UHECRs interaction probability. In this work, we explore the effects induced by modified kinematics in the UHECR lightest component phenomenology from the QG perspective. We explore the possibility of a geometrical description of the massive fermions interaction with the supposed quantum structure of spacetime in order to introduce a Lorentz covariance modification. The kinematics are amended, modifying the dispersion relations of free particles in the context of a covariance-preserving framework. This spacetime description requires a more general geometry than the usual Riemannian one, indicating, for instance, the Finsler construction and the related generalized Finsler spacetime as ideal candidates. Finally we investigate the correlation between the magnitude of Lorentz covariance modification and the attenuation length of the photopion production process related to the GZK cut-off, demonstrating that the predicted opacity horizon can be dilated even in the context of a theory that does not require any privileged reference frame.

BIBECHANA ◽  
2014 ◽  
Vol 11 ◽  
pp. 17-24
Author(s):  
Saroj Nepal

The Greisen-Zatsepin-Kuzmin (GZK) cutoff (5 × 1019eV) of special relativity in the observed ultra high energy cosmic rays (UHECR) spectrum is one of the most puzzling paradoxes in physics. Experimentally a number of cosmic ray events have been detected above this GZK limit which is known as UHECR paradox. We propose a resolution of this paradox through a modification of the relativistic kinematics keeping in mind that it should not lead to predictions different from those of special relativity in the well tested domains. It is shown that theoretical limit in UHECR spectrum can be explained in the framework of Lorentz invariance violation (LIV) theories which assume the existence of a preferred frame. The present paper proposes that the velocity of the solar system with respect to the rest frame of the universe plays a role in explaining the paradox. DOI: http://dx.doi.org/10.3126/bibechana.v11i0.10375   BIBECHANA 11(1) (2014) 17-24


Symmetry ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 1961
Author(s):  
Marco Danilo Claudio Torri ◽  
Lorenzo Caccianiga ◽  
Armando di Matteo ◽  
Andrea Maino ◽  
Lino Miramonti

Ultra high energy cosmic rays (UHECRs) may interact with photon backgrounds and thus the universe is opaque to their propagation. Many Lorentz Invariance Violation (LIV) theories predict a dilation of the expected horizon from which UHECRs can arrive to Earth, in some case even making the interaction probability negligible. In this work, we investigate this effect in the context of the LIV theory that goes by the name of Homogeneously Modified Special Relativity (HMSR). In this work, making use of a specifically modified version of the SimProp simulation program in order to account for the modifications introduced by the theory to the propagation of particles, the radius of the proton opacity horizon (GZK sphere), and the attenuation length for the photopion production process are simulated and the modifications of these quantities introduced by the theory are studied.


2004 ◽  
Vol 19 (24) ◽  
pp. 1829-1840 ◽  
Author(s):  
FAY DOWKER ◽  
JOE HENSON ◽  
RAFAEL D. SORKIN

Contrary to what is often stated, a fundamental spacetime discreteness need not contradict Lorentz invariance. A causal set's discreteness is in fact locally Lorentz invariant, and we recall the reasons why. For illustration, we introduce a phenomenological model of massive particles propagating in a Minkowski spacetime which arises from an underlying causal set. The particles undergo a Lorentz invariant diffusion in phase space, and we speculate on whether this could have any bearing on the origin of high energy cosmic rays.


2009 ◽  
Vol 18 (10) ◽  
pp. 1621-1625
Author(s):  
LUCA MACCIONE ◽  
ANDREA M. TAYLOR ◽  
DAVID M. MATTINGLY ◽  
STEFANO LIBERATI

We investigate the consequences of higher dimension Lorentz violating, CPT even kinetic operators that couple standard model fields to a non-zero vector field in an Effective Field Theory framework. Comparing the ultra-high energy cosmic ray spectrum reconstructed in the presence of such terms with data from the Pierre Auger Observatory allows us to establish stringent bounds on O(E/M Pl )2 suppressed violations of Lorentz invariance.


Universe ◽  
2021 ◽  
Vol 7 (9) ◽  
pp. 345
Author(s):  
Tomislav Terzić ◽  
Daniel Kerszberg ◽  
Jelena Strišković

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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