Tag Archives: Evento scientifico

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: 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: Gino Isidori (UZH) What is the origin of the different masses for quarks and leptons is one of the big open questions in particle physics. I will briefly review this problem, illustrating its central role in achieving a deeper understanding of fundamental interactions. I will also outline some recent theoretical ideas on how to address it, focusing in particular on the concept of “flavor deconstruction”, and finally discuss how these ideas can be tested through current and future flavor-physics experiments.

Speaker: Giancarlo Ferrera (Istituto Nazionale di Fisica Nucleare) We present a resummed QCD calculation of the thrust distribution in electron-positron annihilation in the back-to-back region up to N^4LL accuracy, matched to fixed-order results up to NNLO. We perform the resummation of the large Sudakov logarithms in the Laplace-conjugated space, and we show that the results differ significantly from those obtained through resummation in thrust space. We include non-perturbative corrections using an analytic hadronization model that depends on two free parameters. Finally, we present a comparison of our predictions with experimental data at the Z-boson peak, and we extract a value for the QCD coupling that is fully consistent with the world average.

Speaker: Pier Giuseppe Catinari (Istituto Nazionale di Fisica Nucleare) In this talk, I will explore how effective field theories (EFTs) provide a powerful framework for describing interactions—particularly non-linear couplings—between dark matter particles and the collective excitations of target materials. I will focus specifically on the interaction between axion dark matter and magnons, which are quasiparticles arising from spin-wave excitations in antiferromagnetic materials. Materials such as nickel oxide emerge as optimal candidates for detecting sub-MeV dark matter with spin-dependent interactions, as well as for the absorption of meV-scale QCD axions.  

Speaker: Masaki Hori (Imperial College London) We propose the first laser spectroscopy of an atom containing a kaon at DAPHNE, which may eventually allow the precision on the charged kaon mass to be improved by 2 to 3 orders of magnitude compared to now, and establish upper limits on beyond-the-standard model forces that may arise between kaons and the other constituent particles of the atom. Metastable kaonic helium is a three-body atom consisting of a helium nucleus, an electron, and kaon occupying a Rydberg state. The atom has an anomalously long lifetime of 10 ns which makes it amenable to laser spectroscopy. Quantum electrodynamics calculations for these atoms currently achieve parts-per-billion scale precision. We have carried out similar experiments at the Antiproton Decelerator of CERN for many years and determined the antiproton-to-electron mass ratio to a precision of 8 parts in 10^10; laser spectroscopy of pionic helium atoms which have a lifetime of 7 ns was also recently achieved at the 590 MeV/c ring cyclotron facility of Paul Scherrer Institute. This increases our confidence that laser spectroscopy of the kaonic variety is now possible, utilizing the modern advances in laser technology. The experiment critically relies on the low-energy kaons of small energy spread which are only available at DAPHNE. Some of the technical challenges of achieving this goal in DAPHNE will be described.  

Speaker: Prof. Luca Visinelli (Shanghai Jiao Tong University) The QCD axion, originally proposed to resolve the strong CP problem, is also a compelling dark matter (DM) candidate. In strong magnetic fields, such as those surrounding neutron stars, axions can convert into photons, potentially generating detectable radio signals. This axion-photon coupling offers a unique avenue for experimental searches in a well-defined mass range. In this seminar, I will present an observational study using the Green Bank Telescope (GBT) to search for transient radio signals from axion-photon conversion. Focusing on the core of Andromeda, we employ the VErsatile GBT Astronomical Spectrometer (VEGAS) and the X-band receiver (8–10 GHz) to probe axions with masses between 33 and 42 μeV, achieving a mass resolution of 3.8 × 10^-4 μeV. We describe our observational strategy and analysis techniques, which reach an instrumental sensitivity of 2 mJy per spectral channel. While no candidate signals exceeding the 5σ threshold were detected, I will discuss future improvements, including expanding the search to additional frequency bands and refining theoretical models, to strengthen constraints on axion DM scenarios.

Speaker: Silvia Tosi The life of the stars is characterized by several processes able to change their chemical composition and structure. The impact and the way with which these mechanisms are active depends on several factors and the most relevant is the mass with which these stars were formed. The present talk will retrace the evolution of the low- and intermediate-mass stars (LIMS), characterized by masses between 1 and 8 solar masses. During their evolution, the LIMS will cross the asymptotic giant branch (AGB) phase, which is characterized by nucleosynthesis and physical phenomena able to deeply alter their surface chemistry. It is well known that during this stage, the circumstellar envelope is an ideal environment for the formation of dust, whose mineralogy reflects the evolutionary history that the star has undergone. Since the LIMS are major sources for the chemical enrichment of the interstellar medium, it is fundamental to characterize the dust formed and to understand the reprocessed elements that will contaminate the host galaxies. In addition, in most cases, the surface chemical composition of the star remains relatively stable during the transition from the AGB to the planetary nebula phase, and for this reason, it is possible to use the stages that occur after the AGB one to retrieve information on the processes that were active during the AGB evolution (e.g. nucleosynthesis, mass-loss, dust production). This talk will show the potentialities of the studies focused on the dust, connecting the mineralogy of the dust observed with the past evolutionary …

Speaker: Giulio Marino (Istituto Nazionale di Fisica Nucleare) We propose a novel framework where MeV-scale Dirac Dark Matter annihilates into axion-like particles, providing a natural explanation for the 511 keV gamma-ray line observed in the Galactic Center. The relic abundance is determined by p-wave annihilation into two axion-like particles, while s-wave annihilation into three axion-like particles, decaying into e+e− pairs, accounts for the line intensity. Remarkably, this model, assuming a standard Navarro-Frenk-White profile, reproduces the observed emission morphology, satisfies in-flight annihilation and cosmological bounds, and achieves the correct relic density, offering a compelling resolution to this longstanding anomaly.  

Speaker: Giorgio Dho (Istituto Nazionale di Fisica Nucleare) X-ray polarimetry is an observational technique with the potential to enrich our understanding of high-energy astrophysics by enabling the measurement of the polarization of X-rays emitted by exotic cosmic phenomena such as black holes, neutron stars, Gamma-Ray Bursts and more. This technique provides crucial insights into the magnetic field geometries and intensities, and emission mechanisms of these sources, offering valuable information that could improve the current knowledge of these astrophysical objects significantly. Currently, the IXPE space observatory, which features a photoelectric polarimeter with an active volume of 6.75 cm3, is the only instrument providing X-ray polarimetric measurements. The PRIN project “HypeX: High Yield Polarimetry Experiment in X-rays”, developed by a collaboration of GSSI, INFN and INAF researchers, aims to apply more modern experimental techniques for applications in X-ray polarization measurements in the energy range between 10 and 40 keV. One branch of the project, GPD3D, builds on the IXPE detector concept, a Time Projection Chamber (TPC) with GEM-based amplification stage. The goal is to achieve 3D track reconstruction and better polarimetric performances by employing more advanced readout and amplification systems, namely an InGrid structure readout by TimePix3 chip. On the other hand, the Xray-CMOS subproject inherits the knowhow and detector concept from the CYGNO/INITIUM directional dark matter experiment optimizing it to this physics search. The technology, a TPC with triple-GEM amplification stage and optical readout exploiting the sensitivity and granularity of sCMOS cameras and PMTs, aims to achieve 3D reconstruction and an …