New preprint: Quantum gravity phenomenology at the dawn of the multi-messenger era — A review (arXiv: 2111.05659 [hep-ph])

The exploration of the universe has recently entered a new era thanks to the multi-messenger paradigm, characterized by a continuous increase in the quantity and quality of experimental data that is obtained by the detection of the various cosmic messengers (photons, neutrinos, cosmic rays and gravitational waves) from numerous origins. They give us information about their sources in the universe and the properties of the intergalactic medium. Moreover, multi-messenger astronomy opens up the possibility to search for phenomenological signatures of quantum gravity. On the one hand, the most energetic events allow us to test our physical theories at energy regimes which are not directly accessible in accelerators; on the other hand, tiny effects in the propagation of very high energy particles could be amplified by cosmological distances. After decades of merely theoretical investigations, the possibility of obtaining phenomenological indications of Planck-scale effects is a revolutionary step in the quest for a quantum theory of gravity, but it requires cooperation between different communities of physicists (both theoretical and experimental). This review is aimed at promoting this cooperation by giving a state-of-the art account of the interdisciplinary expertise that is needed in the effective search of quantum gravity footprints in the production, propagation and detection of cosmic messengers.

This review is the outcome of the collective efforts of the participants of the COST Action CA18108 “Quantum Gravity Phenomenology in the multi-messenger approach”, and expresses a very fruitful collaboration between the theorists, phenomenologists, and experimentalists that participate in this endeavor. It is complemented by a catalogue, the QG-MM Catalogue, containing experimental bounds of QG effects on astrophysical data.

New preprint: Interplay between spacetime curvature, speed of light and quantum deformations of relativistic symmetries (arXiv: 2110.04867 [gr-qc])

Interplay between spacetime curvature, speed of light and quantum deformations of relativistic symmetries
Angel Ballesteros, Giulia Gubitosi, Flavio Mercati

Recent work showed that κκ-deformations can describe the quantum deformation of several relativistic models that have been proposed in the context of quantum gravity phenomenology. Starting from the Poincaré algebra of special-relativistic symmetries, one can toggle the curvature parameter ΛΛ, the Planck scale quantum deformation parameter κκ and the speed of light parameter cc to move to the well-studied κκ-Poincaré algebra, the (quantum) (A)dS algebra, the (quantum) Galilei and Carroll algebras and their curved versions. In this review, we survey the properties and relations of these algebras of relativistic symmetries and their associated noncommutative spacetimes, emphasizing the nontrivial effects of interplay between curvature, quantum deformation and speed of light parameters.

Job Announcement: Postdoctoral positions in Naples

The quantum gravity group at the Physics Department of the University of Naples “Federico II” is seeking candidates for two postdoctoral positions, one for which applications are already being accepted and one for which the application period will start at some point this coming Spring.
For both positions the most natural candidate would be a young quantum-gravity researcher or astrophysicist with some expertise (or at least tangible evidence of interest) in Quantum Gravity Phenomenology, but candidates from all areas of quantum-gravity research are encouraged to apply. 

The first position is a two-year position with a yearly gross salary of 31.213,48 € (plus a mobility incentive of 5.000 €/year for candidates who were not previously employed in Naples). It is reserved to non-Italian citizens or Italian citizens who, at the submission deadline, hold a position in a foreign institution and have been continuously abroad for at least three years.Information on the application and selection procedures, whose official language is English, is available at this link (job announcement N. 23590):

The second position is a one-year position (with realistic chances for a second year extension) with a yearly salary of about 29k euros and is open to all candidates. The official language of this second procedure will be Italian, though most of it will be manageable also in English and knowledge of the Italian language is not required. 
When appropriate we shall post updated information on these positions on the website of the group:

New preprint: Fuzzy worldlines with κ-Poincaré symmetries (arXiv: 2109.09699 [hep-th])

Fuzzy worldlines with κ-Poincaré symmetries
Angel Ballesteros, Giulia Gubitosi, Iván Gutierrez-Sagredo, Flavio Mercati

A novel approach to study the properties of models with quantum-deformed relativistic symmetries relies on a noncommutative space of worldlines rather than the usual noncommutative spacetime. In this setting, spacetime can be reconstructed as the set of events, that are identified as the crossing of different worldlines. We lay down the basis for this construction for the κκ-Poincaré model, analyzing the fuzzy properties of κκ-deformed time-like worldlines and the resulting fuzziness of the reconstructed events.


Conference announcement: COST Action QG-MM Second Annual Conference – October 2021

I am co-organizing the following meeting, which will be held In October in Corfu (Greece):

COST CA18108 Second Annual Conference

This is the second Annual Conference organized by COST Action CA18108, an initiative funded by the COST Association, aiming to enable researchers from different communities of quantum gravity theorists and phenomenologists and gamma-ray, neutrino, cosmic-ray and gravitational-wave experimentalists to learn about each other’s work and cooperate on the goal of developing new strategies for testing candidate quantum gravity theories using multi-messenger high-energy astrophysical observations.  

It will be possible to attend in person in Corfu (preferred mode) or to follow the conference online. 

The conference will be accompanied by a topical Special Issue on Quantum Gravity Phenomenology and Multi-Messenger astronomy in Classical and Quantum Gravity (CQG), which will be edited by members of the QGMM Cost Action. We invite all participants of our second annual conference to contribute to the special issue with original research papers which meet the topical criterion. The focus issue will open for submission for 6 months after the conference (with some flexibility).


Training School: COST CA18108 First Training School “Quantum gravity phenomenology in the multi-messenger approach”

I am co-organizing the following Training School, which will be held in September in Corfu (Greece):

COST CA18108 First Training School Quantum gravity phenomenology in the multi-messenger approach

It’s now 20 years since the first Doubly Special Relativity papers appeared on ArX

This is the first of a series of Training Schools organized by the European COST Action CA18108 – “Quantum Gravity Phenomenology in the Multi-Messenger Approach”(, an initiative funded by the COST Association (, whose goal is to investigate possible signatures predicted by quantum gravity models in the observation of different cosmic messengers, such as gamma rays, neutrinos, cosmic rays and gravitational waves.

The success of this endeavor requires the close collaboration of scientists from very different backgrounds, ranging from experimentalists specialized in data collection and analyses for specific cosmic messengers, to theorists working on different quantum gravity models.

A fundamental ingredient to make such cooperation effective is to share a common language and be familiar with the tools used by the different communities. This is where the role of this school comes in as fundamental: its goal is to start training a generation of young scientists in the interdisciplinary expertise on quantum gravity theories and models and on experimental and theoretical approaches to multi-messenger astroparticle physics.

As such, the different editions of the Training School will offer lectures from experts on different facets of the scientific gear the students will acquire, including data analysis and interpretation for individual sources, the creation and analysis of joint datasets of different cosmic messengers, the interplay between quantum gravity theory modeling and phenomenological predictions.  

The school is aimed at Master and PhD students, as well as early-career postdocs. 

It will be possible to attend in person in Corfu (preferred mode) or to follow the school online. The lectures will be recorded and the lecture notes will later be published so that it will be possible to use them as preliminary material for the remaining Training Schools (two are foreseen), that will build on the present one to more advanced topics.

The school will be followed by the COST CA18108 Second Annual conference. Those interested in participating should register on the Conference website.

New preprint: The group structure of dynamical transformations between quantum reference frames (arXiv: 2012.15769 [quant-ph])

The group structure of dynamical transformations between quantum reference frames
Angel Ballesteros, Flaminia Giacomini, Giulia Gubitosi

Recently, it was shown that when reference frames are associated to quantum systems, the transformation laws between such quantum reference frames need to be modified to take into account the quantum and dynamical features of the reference frames. This led to a relational description of the phase space variables of the quantum system of which the quantum reference frames are part. While such transformations were shown to be symmetries of the system’s Hamiltonian, the question remained unanswered as to whether they enjoy a group structure, similar to that of the Galilei group relating classical reference frames in quantum mechanics. In this work, we identify the canonical transformations on the phase space of the quantum systems comprising the quantum reference frames, and show that these transformations close a group structure defined by a Lie algebra, which is different from the usual Galilei algebra of quantum mechanics. We further find that the elements of this new algebra are in fact the building blocks of the quantum reference frames transformations previously identified, which we recover. Finally, we show how the transformations between classical reference frames described by the standard Galilei group symmetries can be obtained from the group of transformations between quantum reference frames by taking the zero limit of the parameter that governs the additional noncommutativity introduced by the quantum nature of inertial transformations.

Conference announcement: DSR20 online meeting

I am co-organizing the following online meeting, which will be held next week:


It’s now 20 years since the first Doubly Special Relativity papers appeared on ArXiv. Several research groups have worked on DSR-relativistic models, leading to significant progress, but some grey areas remain on the conceptual side and additional phenomenological avenues are much needed. The meeting “DSR20” (an online meeting, using zoom) intends to be an opportunity for an exchange of ideas on these matters. DSR20 will be held from december 14 to december 16 and it will be scheduled so to allow colleagues in different parts of the world to attend at least some of the sessions. 

New preprint: Generalized noncommutative Snyder spaces and projective geometry (arXiv: 2007.09653 [hep-th])

Generalized noncommutative Snyder spaces and projective geometry
Giulia Gubitosi, Angel Ballesteros, Francisco J. Herranz

Given a group of kinematical symmetry generators, one can construct a compatible noncommutative spacetime and deformed phase space by means of projective geometry. This was the main idea behind the very first model of noncommutative spacetime, proposed by H.S. Snyder in 1947. In this framework, spacetime coordinates are the translation generators over a manifold that is symmetric under the required generators, while momenta are projective coordinates on such a manifold. In these proceedings we review the construction of Euclidean and Lorentzian noncommutative Snyder spaces and investigate the freedom left by this construction in the choice of the physical momenta, because of different available choices of projective coordinates. In particular, we derive a quasi-canonical structure for both the Euclidean and Lorentzian Snyder noncommutative models such that their phase space algebra is diagonal although no longer quadratic.