Tag Archives: Evento scientifico

Speaker: Lorenzo Calibbi (Nankai University) I will present a recent work where we assessed the capability of Gravitational Wave (GW) experiments to probe the origin of the flavour sector of the Standard Model. Within the context of the Froggatt-Nielsen mechanism to generate the hierarchical patterns of fermion masses and mixing based on a gauged U(1) flavour symmetry, we investigated the formation of cosmic strings and the resulting GW background (GWB), estimating the sensitivity to the model’s parameter space of future GW observatories. Comparing these results with the bounds from low-energy flavour observables, we found that these two types of experimental probes of the model are nicely complementary. In certain scenarios, the combination of flavour constraints and future GW bounds can bring about a complete closure of the parameter space, which (once again) illustrates the potential of GWB searches to test fundamental interactions at ultra-high energy scales beyond the reach of laboratory experiments.

Speaker: Gianluca Cavoto (Istituto Nazionale di Fisica Nucleare) The observation of a resonance structure in the opening angle of the electron-positron pairs in the 7Li(p,e+e−)8Be reaction was claimed and interpreted as the production and subsequent decay of a hypothetical particle (X17). Similar excesses, consistent with this particle, were later observed in processes involving 4He and 12C nuclei with the same experimental technique. The MEG-II apparatus at PSI, designed to search for the µ+ → e+ γ decay, can be exploited to investigate the existence of this particle and study its nature. Protons from a Cockroft-Walton accelerator, with an energy up to 1.1 MeV, were delivered on a dedicated Li-based target. The γ and the e+ e− pair emerging from the 8Be transitions were studied with calorimeters and a spectrometer, featuring a broader angular acceptance than previous experiments. In this seminar we present the analysis and the result of a four-week data-taking in 2023 with proton energy varying from 400 keV to 1080 keV, resulting in the excitation of two different resonances with Q-value 17.6 MeV and 18.1 MeV.

Speaker: Sven Heinemeyer (IFCA (CSIC, Santander)) The baryon asymmetry of the universe naturally leads to BSM Higgs sectors. Such models contain additional Higgs bosons w.r.t. the SM Higgs boson, leading to a Higgs potential substantially more complicated than in the SM. The measurement of triple Higgs couplings (THCs) is key to determinethe shape of the multi-dimensional potential, which are best accessedvia di-Higgs produciton. So far most investigationsfocused on the THC of the SM-like Higgs boson discovered at the LHC in 2012. We go beyond these analyses and show how BSM THCs may be determined atcurrent and future colliders, including the HL-LHC, future linear e+e-colliers and a future muon collider.

Speaker: Alessandro Lella (Istituto Nazionale di Fisica Nucleare) Core-collapse Supernovae (SN) are among the most powerful astrophysical sources of feebly-interacting particles. Indeed, the extreme conditions of temperature and density reached after the gravitational collapse make the SN core a unique environment to have a significant production of novel exotic particles, such as axions and axion-like particles. In this seminar, I discuss how axions and ALPs could be copiously produced in a SN core by means of their coupling with nuclear matter. In particular, I will show that the ALP parameter space can be severely constrained by employing observations of the neutrino burst from SN 1987A. Moreover, ALPs are coupled to photons or leptons are provided with a vast phenomenology due to decays and oscillations in Galactic magnetic fields, leading to observable signatures, which may eventually shed light on controversial features characterizing the SN core.”

Speaker: Gustavo Conesa Balbastre (LPSC-CNRS Grenoble) The ALICE experiment at the LHC is devoted to test QCD predictions, and in particular, the measurement of the properties of the Quark-Gluon plasma created in ultra-relativistic heavy-ion collisions. Among the different probes that the experiment explores, neutral mesons and isolated photons are useful to study the jet-quenching effect in the QGP: the loss of energy of high energy partons (quarks and gluons) produced at the initial stages of the collision traversing the strongly interacting plasma. Such probes are measured in ALICE by its electromagnetic calorimeters PHOS and EMCal, combined with the central tracking systems. The Frascati-LNF-INFN and Grenoble-LPSC-CNRS groups had a strong involvement in the construction and exploitation of the EMCal calorimeter where I was involved. In this presentation I will present the different results obtained with the calorimeter during the LHC Run 1 and 2 data, concentrating on the isolated photons production.

Speaker: Livio Verra (Istituto Nazionale di Fisica Nucleare) The extremely large accelerating fields that can be excited in plasmas are orders of magnitudes larger than in conventional accelerators, and they could be used to miniaturise the ever-increasing footprint of light sources and high-energy physics facilities. In this seminar I will review the concepts of plasma wakefield acceleration, present the main experimental results of the field, and discuss the challenges on the path towards applications for high-energy physics.

Speaker: Marialuisa Aliotta Nuclear reactions in stars are responsible for the synthesis of nearly all elements beyond primordial hydrogen and helium. These reactions occur at extremely low energies and have cross sections that are difficult to measure directly in laboratory conditions due to natural and cosmic-ray-induced background. As a result, many reaction rates relevant to stellar evolution and nucleosynthesis rely on uncertain extrapolations, limiting the predictive power of astrophysical models. The Laboratory for Underground Nuclear Astrophysics (LUNA), located beneath 1.4 km of rock at the Gran Sasso National Laboratory in Italy, offers a unique environment for measuring these reactions at the relevant astrophysical energies. By dramatically suppressing background radiation, LUNA has enabled direct studies of key processes that power stars and shape the chemical evolution of the Universe. In this talk, I will review selected results from LUNA’s low energy experiments and discuss their implications for astrophysics. I will also highlight current challenges and open questions, outlining prospects for future experimental efforts and collaborative research.  

Speaker: Andrea Banfi (University of Sussex) Jet observables such as event-shape distributions and jet rates are widely used for precision determinations of the strong coupling. The accuracy of perturbative calculations for such observables is very high, and poorly known hadronisation corrections limit the precision of such determination. I present a general method, based on the existing theoretical framework ARES (Automated Resummer for Event Shapes), to estimate hadronisation corrections up to a single universal non-perturbative parameter, which can be determined from data. The method can be applied to an arbitrary observable and gives promise to impact future determinations of the strong coupling with jet observables.    

Speaker: Fabio Galasso (Roma La Sapienza Univ.) Representation learning is an important part of modern computer vision. Literature assumes a default Euclidean space, thus a manifold based on regular grids. Only most recently, hyperbolic spaces have enabled techniques to reach and surpass the state-of-the-art, supporting learning with hierarchical structures and uncertainty, also a by-product of hyperbolic representation learning. I will introduce our most recent work that leverages Hyperbolic Neural Networks for anomaly detection, self-supervised learning of actions, active learning of semantic segmentation, and reinforcement learning of robot navigation in social environments.

Speaker: Reinier Meijer (Utrecht Univ.) Gravitational waves are displacements in gravitational fields which have allowed us unique astronomical insights, such as the first measurements of binary black holes. Before their very first detection in 2015, gravitational waves were unsure to exist. Even Einstein himself at one point tried to submit a paper in which he disclaimed them. He thought that surely they could not exist, and even if they did, their scale would forever remain unmeasurable. Such was the triumph when a gravitational wave was first detected in 2015, a full century after the theory of general relativity had been established. In this seminar we will look into: • A sketch of how gravitational waves arise from general relativity; • The methods used to establish the current catalogue of detections; • Current developments in anticipation of the new generations of observatories.