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Andrea Bevilacqua

Publications and source records attributed to Andrea Bevilacqua.

18 recordsLinked to original sources
arXiv2026

Generalized relative locality and causal sets

In this paper we introduce a new general framework for the study of phenomenological quantum gravity theories (PQG). The key idea is the introduction of two different types of spacetime, an observer-independent spacetime (modeled by a smooth orientable manifold) and an observer-dependent one (which has an inherently discrete causal set structure). The interaction between the two allows us to prove the main result of the paper: relative locality can be obtained in general PQG models, regardless of momentum-space curvature. {We also discuss the treatment of spacetime symmetries in our model, and introduce a direct link between spacetime symmetries and relative locality effects.} Our construction is presented in a coordinate-independent way and is based on fibre bundles where spacetime, rather than momentum-space, is the base manifold. This makes causality manifest even in general models with relative locality. Furthermore, it allows for the application of this formalism to cosmology on general backgrounds, something which is not clearly possible in the canonical approach to relative locality, where momentum-space serves as the base manifold.

gr-qc↗
arXiv2026

Asymmetry in momentum space: restoring ${\cal C}{\cal P}{\cal T}$ invariance of $κ$-field theory

The positive and negative energy modes of a field theory in $κ$-Minkowski/$κ$-Poincaré noncommutative spacetime have very different symmetry properties. This can be understood geometrically by considering that they span two distinct sectors of a curved momentum space. By performing an explicit direct computation of the relativistic Noether charges and their algebra within the canonical formalism, we identify a striking consequence of this asymmetry in momentum space: charge conjugation and Poincaré invariance are incompatible. We then notice how the structure of momentum space suggests that time reversal could be deformed so that the overall ${\cal C}{\cal P}{\cal T}$-invariance is restored. We prove that this new proposal works by studying the transformation properties under deformed discrete symmetries of the new relativistic charges.

hep-th↗
arXiv2025

Cutkosky rules and 1-loop $κ$-deformed amplitudes

In this paper we show that the Cutkosky cutting rules are still valid term by term in the expansion in powers of $κ$ of the $κ$-deformed 1-loop correction to the propagator. We first present a general argument which relates each term in the expansion to a non-deformed amplitude containing additional propagators with mass $M>κ$. We then show the same thing more pragmatically, by reducing the singularity structure of the coefficients in the expansion of the $κ$-deformed amplitude, to the singularity structure of non-deformed loop amplitudes, by using algebraic and analytic identities. We will explicitly show this up to second order in $1/κ$, but the technique can be generalized to higher orders in $1/κ$. Both the abstract and the more direct approach easily generalize to different deformed theories. We will then compute the full imaginary part of the $κ$-deformed 1-loop correction to the propagator in a specific model, up to second order in the expansion in $1/κ$, highlighting the usefulness of the approach for the phenomenology of deformed models. This explicitly confirms previous qualitative arguments concerning the behaviour of the decay width of unstable particles in the considered model.

hep-th↗
arXiv2025

\kappa-deformed spin-1/2 field

In this paper, we investigate the Poincar\'e and discrete symmetries of a $\kappa$-deformed spin-$\tfrac12$ field, extending recent results obtained for scalar fields. We construct an action that is Poincar\'e invariant and analyze its consequences within the deformed framework. Our results confirm the findings of our recent analysis of the $\kappa$-deformed scalar field, where we established that there is no action invariant under both Poincar\'e symmetry and charge conjugation in the $\kappa$-deformed case, while $\mathcal{CPT}$-symmetry can be restored through a natural deformation of time reversal. Furthermore, we present an explicit calculation of the Noether charges associated with Poincar\'e symmetry and show that their algebra closes, demonstrating the internal consistency of the theory.

hep-th↗
arXiv2024

Deformation-induced CPT violation in entangled pairs of neutral kaons

In this paper we consider description of kaon -- anti-kaon interference in the context of a theory with deformed $\cal CPT$ symmetry. In the case of such theoretical models, deviations from the standard $\cal CPT$ invariance is related to the momentum carried by the particles; in particular the rest masses of particles and antiparticles are equal. We find that the decay intensity of kaon -- anti-kaon pair has three contributing terms: the correct-parity, the wrong-parity, and the interference between them, all of which are affected by deformation. Using the fact that the presence of such terms were not observed we estimate the magnitude of deformation parameter $κ\gtrsim 10^{18}$ GeV, very close to the expected Planck mass scale. This raises hopes that the effect, if exists, could be detected in a near future accelerator experiments. An uncertainty of the energy measurement is crucial for accuracy of these predictions.

hep-ph↗
arXiv2023

$κ$-deformed scalar field

In the following work we will introduce and discuss in detail a particular model of complex $κ$-deformed scalar field, whose behaviour under C, P , T transformation is particularly transparent from both a formal and phenomenological point of view. We will begin by introducing the key mathematical structure at the basis of our investigation, namely the $κ$-Poincaré (Hopf) algebra and the $κ$-Minkowski spacetime. We will then investigate the behaviour of general two-particle states under deformed boost. After this we will introduce the action of our $κ$-deformed complex scalar field. From it, we will derive the equations of motion, as well as the Noether charges due to the continuous symmetries. The peculiar features of $κ$-deformation in general, and of our model in particular, allow for very non-trivial interaction between discrete and continuous symmetries, of which we will investigate the phenomenological consequences (particularly in terms of difference of lifetime of decaying particles). To conclude, we will obtain the $κ$-deformed propagator of the $κ$-deformed complex scalar field, and the imaginary part of the 1-loop contribution to it, ending with additional phenomenological consequences. The third chapter is new, unpublished work.

hep-th↗
arXiv2023

Quantum Gravity Phenomenology and Particle Physics

Quantum gravity phenomenology has been historically regarded as a difficult endeavour, due to the apparent scarcity of phenomena involving the required scales of length (Planck length $l_P$) and energy (Planck energy $E_P$). It was realized, however, that one can look for cumulative effects of a quantum theory of gravity at energies $E/E_P \ll 1$ if even tiny effects are amplified by the large time of flight or very high energies, common to astrophysical phenomena. In the this work, complementary to the COST action CA18108 White Book, we put forward a proposal that quantum gravity phenomenology can be fruitfully pursued also with the help of terrestrial particles accelerators. We first discuss the theoretical background, and then concentrate on deformed discrete symmetries C,P,T. We investigate possible experimental signatures of CPT deformation, particularly concerning the difference in decay time between particles and antiparticles, and fields interference.

hep-ph↗
arXiv2023

Finite $κ$-deformed two-particle boost

In this paper we consider the \k{appa}-deformed boost acting on a two-particles states. Using techniques developed in the case of infinitesimal boost we compute explicit expression for the components of the finite boost matrices acting on the first and second particle. We briefly discuss phenomenological consequences of our findings.

hep-th↗
arXiv2023

Complex scalar field in $κ$-Minkowski spacetime

It is often expected that one cannot treat spacetime as a continuous manifold as the Planck scale is approached, because of to possible effects due to a quantum theory of gravity. There have been several proposals to model such a deviation from the classical behaviour, one of which is noncommutativity of spacetime coordinates. In this context, the non-commutativity scale is seen as an observer-independent length scale. Of course, such a scale impose a modification of ordinary relativistic symmetries, which now need to be deformed to accommodate this fundamental scale. The $κ$-Poincaré algebra is an example of this deformation. In what follows I will briefly describe a construction of a $κ$-deformed complex scalar field theory, while at the same time shedding light on the behaviour of discrete and continuous symmetries in this formalism. This in turn will open the way to the study of the application of this formalism to actual physical processes. I will then conclude with some comments and prospects for the future.

gr-qc↗
arXiv2022

$κ$-deformed complex fields, (discrete) symmetries, and charges

We will briefly describe how to build a field theory of a complex scalar field in the $κ$-Minkowski spacetime. After introducing the action, we will shortly describe its properties under both continuous and deformed symmetry transformations. We will then describe how to compute the charges and describe their non-trivial properties due to $κ$-deformation. We will conclude with the experimental significance of the model, particularly in the context of decay probability differences between particles and antiparticles.

hep-th↗
arXiv2022

$κ$-deformed complex scalar field: conserved charges, symmetries and their impact on physical observables

In this paper we revisit the model of $κ$-deformed complex scalar field. We find that this model possesses ten conserved Noether charges that form, under commutators, a representation of (undeformed) Poincaré algebra. It follows that the theory is relativistic and does not break Lorentz invariance. However the spacetime representation of boosts is not standard, and contains a non-local translation, different for positive and negative energy modes. It then follows that although the masses of particles and anti-particles are equal, the theory violates CPT symmetry in a subtle way. We explain why the Jost-Wightman-Greenberg theorem of equivalence of the Poincaré symmetry and CPT fails in our case. Finally, we discuss the phenomenological consequences of the theory and its possible observational signatures.

hep-th↗
arXiv2022

Doubly Special Relativity and Relative Locality

This is a write-up of two lectures delivered at COST CA18108 First Training School. They cover the motivations and some basic technical results in the field of Doubly Special Relativity and Relative Locality. The energy-dependent speed of light is a recurring theme here. The soccer ball problem is also briefly described. The video recording of these and other lectures can be found at https://www.youtube.com/channel/UChRfzgjTkO9sOkwq358kHZw/videos.

physics.gen-ph↗
arXiv2021

$κ$-deformed complex fields and discrete symmetries

We present a construction of $κ$-deformed complex scalar field theory with the objective of shedding light on the way discrete symmetries and CPT invariance are affected by the deformation. Our starting point is the observation that, in order to have an appropriate action of Lorentz symmetries on antiparticle states, these should be described by four-momenta living on the complement of the portion of de Sitter group manifold to which $κ$-deformed particle four-momenta belong. Once the equations of motions are properly worked out from the deformed action we obtain that particle and antiparticle are characterized by different mass-shell constraints leading to a subtle form of departure from CPT invariance. The remaining part of our work is dedicated to a detailed description of the action of deformed Poincaré and discrete symmetries on the complex field.

hep-th↗
arXiv2019

Notes on the analytic solution of box model equations for gravity-driven particle currents with constant volume

We summarize the physical equations and analytic solutions of three versions of the box model equations, suitable for the integral formulation of axisymmetric gravity-driven particle currents with constant volume. The first model is based on a simple constant resisting stress, while the second and third models assume flow dilution by particle deposition. The third model is characterized by assuming an interstitial fluid lighter than the ambient fluid. All the calculations are performed on a flat topography. Ambient fluid entrainment and cooling effects are not considered. All particles are assumed to deposit at the same velocity.

physics.flu-dyn↗
arXiv2018

Probabilistic enhancement of the Failure Forecast Method using a stochastic differential equation and application to volcanic eruption forecasts

We introduce a doubly stochastic method for performing material failure theory based forecasts of volcanic eruptions. The method enhances the well known Failure Forecast Method equation, introducing a new formulation similar to the Hull-White model in financial mathematics. In particular, we incorporate a stochastic noise term in the original equation, and systematically characterize the uncertainty. The model is a stochastic differential equation with mean reverting paths, where the traditional ordinary differential equation defines the mean solution. Our implementation allows the model to make excursions from the classical solutions, by including uncertainty in the estimation. The doubly stochastic formulation is particularly powerful, in that it provides a complete posterior probability distribution, allowing users to determine a worst case scenario with a specified level of confidence. We apply the new method on historical datasets of precursory signals, across a wide range of possible values of convexity in the solutions and amounts of scattering in the observations. The results show the increased forecasting skill of the doubly stochastic formulation of the equations if compared to statistical regression.

physics.data-an↗
arXiv2018

Comparative analysis of the structures and outcomes of geophysical flow models and modeling assumptions using uncertainty quantification

We present a new statistically driven method for analyzing the modeling of geophysical flows. Many models have been advocated by different modelers for such flows incorporating different modeling assumptions. Limited and sparse observational data on the modeled phenomena usually does not permit a clean discrimination among models for fitness of purpose, and, heuristic choices are usually made, especially for critical predictions of behavior that has not been experienced. We advocate here a methodology for characterizing models and the modeling assumptions they represent, using a statistical approach over the full range of applicability of the models. Such a characterization may then be used to decide the appropriateness of a model and modeling assumption for use. We present our method by comparing three different models arising from different rheology assumptions, and the data show unambiguously the performance of the models across a wide range of possible flow regimes. This comparison is facilitated by the recent development of the new release of our TITAN2D mass flow code that allows choice of multiple rheologies The quantitative and probabilistic analysis of contributions from different modeling assumptions in the models is particularly illustrative of the impact of the assumptions. Knowledge of which assumptions dominate, and, by how much, is illustrated in two different case studies: a small scale inclined plane with a flat runway, and the large scale topography on the SW slope of Volcán de Colima (MX). A simple model performance evaluation completes the presentation.

physics.flu-dyn↗
arXiv2013

An occupation time formula for semimartingales in $\mathbb{R}^{N}$

Inspired by coarea formula in geometric measure theory, an occupation time formula for continuous semimartingales in $\mathbb{R}^{N}$ is proven. The occupation measure of a semimartingale, for $N\geq2$, is singular with respect to Lebesgue measure but it has a bounded density "transversal" to a foliation, under proper assumptions. In the particular case of the foliation given locally by the distance function from a manifold, the transversal density is related to a geometric local time of the semimartingale at the manifolds of the foliation.

math.PR↗