On January 14, 2019, the MAGIC telescopes detected GRB 190114C at teraelectronvolt energies, recording the most energetic photons ever observed from a gamma-ray burst. Using this unique observation, we probe energy dependence of the speed of light in vacuo as predicted by several quantum-gravity models. Based on a set of well-justified assumptions on the possible intrinsic spectral and...
The IceCube Neutrino Observatory at the South Pole is the world's largest neutrino telescope. It instruments a kilometer cube of ice with more than 5000 optical sensors that detect the Cherenkov light emitted by secondary particles produced in neutrino-nucleon interactions in the ice. Covering a wide range of neutrino energies, from a few of GeV to PeV, its physics program is extremely rich,...
Noncommutative models offer a way to incorporate many of the expected features of quantum gravity in the language of Quantum Field Theory. Inspired by astrophysical and cosmological experimental data, we will try to build a noncommutative theory on de Sitter space. We will discuss the general problems that arise in building both the commutative and noncommutative versions, and discuss some of...
I will present a new method for extracting information from UHECR arrival directions, which could shed some new light on the physics of UHECR propagation and origin, as well as hopefully be applicable to using UHECRs as probes of Quantum Gravity effects.
Neutrino oscillation is a quantum phenomenon arising from the interference between mass eigenstates. These oscillations are observable over long distances of thousands of kilometres. It has been hypothesised that quantum gravity effects may act like a thermal bath leading to decoherence in quantum systems. Due to their long coherence lengths, neutrinos may be a powerful tool to probe these...
Cosmic strings are one-dimensional topological defects, which arise naturally in field theories, as well as in scenarios of the early Universe based on superstring theory. One promising strategy to test their existence is to search for their gravitational wave (GW) emission. In particular, strong GW bursts are generated from non-smooth structures such as cusps and kinks, and overlapped GWs...
Gravitational lensing of very high energy photons has recently been observed in the JVAS B0218+357 strong lensing system. This observation opens the possibility of performing a test of gravity at high energy by comparing the difference in propagation time of high energy photons over different travel paths. The time delay is computed in the framework of a LIV (Lorentz Invariance Violation)...
We consider the cosmological application of a (variant of) relatively newly proposed model \cite{1609.06915} unifying inflation, dark energy, dark matter, and the Higgs mechanism. The model was originally defined using additional non-Riemannian measures but it can be reformulated into effective quintessential model unifying inflation, dark energy and dark matter. Here we demonstrate...
We show how matter fields of arbitrary spin, when coupled to a broad class of metric-affine gravity theories (Ricci-Based Gravities), develop non-trivial effective interactions that can be treated perturbatively only below a characteristic high-energy scale Λ_Q, which characterizes when non-metricity-related effects ecome non-perturbative. We then set stringent constraints to Λ_Q by using data...
The Effective Field Theory (EFT) approach turned useful for the description of cosmological perturbations in modified gravity. A similar EFT approach for spherically symmetric, static black holes could provide a new insight into perturbations of beyond Horndeski scalar-tensor black holes. I will present an EFT action depending on a set of scalars cooked up from the metric and embedding...
We disprove the widespread belief that higher order curvature theories of gravity in the metricaffine formalism are generally ghost-free. This is clarified by considering a sub-class of theories constructed only with the Ricci tensor and showing that the non-projectively invariant sector propagates ghost-like degrees of freedom. We also explain how these pathologies can be avoided either by...
In General Relativity (GR) the deflection of light modifies the number and position of images, generates Einstein rings and changes the magnification of images. I review how these weak lensing phenomena are affected by deviations from GR through a number of examples of spherically symmetric lenses in modified gravitational theories. In particular I emphasize that the magnification ratio (flux...
The κ-Poincaré model is a Hopf algebra-based deformation of special relativity featuring a modified dispersion relation, modified momentum conservation law, and relative locality effects. Such a model might emerge in a semi-classical limit of quantum gravity, the Plank mass acting as deformation parameter that characterizes the departure from special relativity and Poincare invariance. Until...
We present a way to derive a relativistic deformation of the kinematics of special relativity from the geometry of a maximally symmetric curved momentum space, and compare this construction, based on the algebra of isometries of the metric in momentum space, with previous attempts of connecting a deformed kinematics with a geometry in momentum space.
We calculate the transition radiation process ν→νγ at an interface of two media or at an edge of magnetic field. The neutrinos are taken to be with only standard-model couplings. The medium or magnetic field fulfills the dual purpose of inducing an effective neutrino-photon vertex and of modifying the photon dispersion relation. The neutrino mass is ignored due to its negligible contribution.
During the last decade, teleparallel theories of gravity have received growing interest as possible contender theories to resolve open questions in cosmology, as well as to provide a formulation of gravity theory which has more similarities with other field theories. An important question arising from these studies is the viability of such theories on smaller scales, such as the solar system,...
We discuss tests of Lorentz invariance, CPT symmetries and quantum gravity from LHAASO experiment in Sichuan province, China. LHAASO would provide new data on 50GeV-100PeV energy window in both gamma rays and charged cosmic rays. This offers a new exciting possibility for searching new physics in Very High Energy Cosmic Rays, from Chinese community.
Lorentz Invariance (LI) is nowadays at the root of our understanding of nature. Even if there is no definitive evidence to sustain departures from LI, there are consistent points indicating that Lorentz Invariance Violation (LIV) can be a consequence of quantum gravity. In this talk we will focus our attention on a new theoretical model HMSR (Homogeneously Modified Special Relativity),...
This talk will review what we know (and we do not know)
about the sources and mechanisms that generate very high energy particles in the Galaxy and in the Universe. These sources can be studied with a multi-messenger (cosmic rays, gamma rays, neutrinos and gravitational waves) observations.
Recent studies have given very important information, but many fundamental question remain open.
Lorentz Invariance Violation introduced as a generic modification to particle dispersion relations is used to study high energy cosmic ray attenuation processes. A complete analysis of the effects of LIV on the propagation of cosmic rays, however, implies a more accurate knowledge of the sources. An other issue is the choice of the models of source distribution. All these topics involve a...
In this talk I address the possibility to measure CPT and Lorentz violation at the Deep Underground Neutrino Experiment. Models of quantum gravity which are non-local can induce Planck suppressed CPT violation, possibly detectable at neutrino experiments. In the first part of the talk I address generic CPT violation, assuming different oscillation patterns for neutrinos and antineutrinos at...
Gravitational wave observations have given us a new observational window on the universe. We are now able to observe signals from highly relativistic collisions of black holes and neutron stars. These observations can be used to test Einstein’s theory of gravity and search for new physics, including possibly hints towards quantum gravity. In this overview talk I will discuss some of the...
We propose to deploy limits that arise from different tests of the Pauli Exclusion Principle in order: i) to provide theories of quantum gravity with an experimental guidance; ii) to distinguish among the plethora of possible models the ones that are already ruled out by current data; iii) to direct future attempts to be in accordance with experimental constraints. We firstly review...
Models of deformed Poincaré symmetries based on group valued momenta have long been studied as effective modifications of relativistic kinematics possibly capturing quantum gravity effects. In this contribution we show how they naturally lead to a generalized quantum time evolution of the type proposed to model fundamental decoherence for quantum systems in the presence of an evaporating black...
In this talk I will describe ongoing efforts to shed light on still-unanswered questions in fundamental physics using cosmological observations. I will explain how we can use measurements of the Supernovae data, Baryon Acoustic Oscillations, Cosmic Microwave Background, Gamma Ray Burst and the large-scale structure of the universe to reconstruct the detailed physics of the dark universe. Also,...
I will introduce the concept of Born geometry that underlies covariant relative locality and general quantum non-locality, consistent with causality. I will then discuss a realization of Born geometry in metastring theory, viewed as a theory of quantum gravity, and show how Born geometry is represented in the zero mode (metaparticle) sector. Finally, I will present a new picture of dark matter...
Various theoretical and phenomenological studies plan to test the validity of Lorentz invariance, one of the grounding symmetries of relativity, and to look for possible signals of Lorentz Invariance Violation (LIV). In this talk we will focus our attention on the LIV impact on high energy neutrino phenomenology, starting from the modifications of dispersion relations and the consequent...
The standard cosmological model has been established and its parameters are now measured with unprecedented precision. This model successfully describes observations from widely different epochs of the Universe, from primordial nucleosynthesis all the way to the present day. However, there is a big difference between modelling and understanding. The next decade will see the era of large...
We present the results of a new analysis of the data of the MiniBooNE experiment taking into account the additional background of photons from Δ+/0 decay. We show that the new background can explain part of the MiniBooNE low-energy excess and the statistical significance of the MiniBooNE indication in favor of short-baseline neutrino oscillation decreases from 5.1σ to 3.3σ.
After the detection of two new pulsars in the past year, the number of the total pulsars observed with the Cherenkov telescopes increased to four. Pulsars are one of the most popular targets both for the current Cherenkov telescopes and CTA. In addition to AGNs and GRBs, pulsars are another important source class for LIV tests because of their fast and periodical flux variabilities. The aim of...
We review various theoretical models and scenarios based on torsional modifications of gravity. Then we present the recent possibility of using multi-messenger astronomy, namely data from gravitational waves observations alongside their electromagnetic counterparts, in order to investigate torsional modified gravity and test general relativity.
I discuss briefly how Planck-scale effects can modify particle kinematics in Friedmann-Robertson-Walker spacetime, both in the LIV (Lorentz Invariance Violation) and in the DSR (Deformed Special Relativity) scenarios. This allows to derive, for some models, a phenomenological formula for in-vacuo dispersion that can be used to constrain the Quantum Gravity scale with astrophysical...
We consider processes crucial for propagation and detection of very-high-energy photons in Lorentz-violating QED: photon decay to an electron-positron pair, photon splitting to three photons, and modified Bethe-Heitler process (pair production in Coulomb field), which is crucial for atmosphere shower formation. Taking into account modified cross-sections for these processes, we show that...
Mirar a lo lejos hacia el espacio es como mirar hacia atrás en el tiempo. Gracias a este truco y a potentes telescopios, hemos capturado la luz y tomado fotos del universo contemporáneo y del universo joven… hasta el universo niño.
Así, hemos aprendido mucho sobre el cosmos que nos rodea, su origen y evolución, y sobre las leyes físicas que lo rigen.
El modelo cosmológico estándar ha...
Understanding gravity in the framework of quantum mechanics is one of the great challenges in modern physics. Along this line, a prime question is to find whether gravity is a quantum entity subject to the rules of quantum mechanics. It is fair to say that there are no feasible ideas yet to test the quantum coherent behaviour of gravity directly in a laboratory experiment. Here, we introduce...
In scenarios with extra dimensions the gravitational interaction may become strong at TeV energies. This could modify the nu-N cross section and imply distinct signals at neutrino telescopes. In particular, cosmogenic neutrinos of E\approx 10^9 GeV could experience frequent interactions with matter where they lose a very small fraction of their energy. We define a consistent model of strong...
Quantum groups can be used to construct noncommutative spacetimes with nonvanishing cosmological constant by using the latter as an explicit parameter, whose vanishing limit leads to the flat Poincaré/Minkowskian models. In particular, the kappa-deformation of the (Anti)-de Sitter group is reviewed, and its associated non commutative (A)dS spacetimes and curved momentum spaces are explicitly...
The multi-messenger approach to the study of Active Galactic Nuclei (AGNs) is of primary importance in astrophysics for the interpretation of mechanisms and scenarios of the emission. Very recently the Astrophysics community gained a wider view of the Active Galactic Nuclei emission with the detection of other messengers such as neutrinos and gravitational waves. Now that, thanks to the...
