Tag Archives: Evento scientifico

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.

Speaker: Angela Papa (Istituto Nazionale di Fisica Nucleare) Electric dipole moments (EDMs) of elementary particles violate time-reversal symmetry. According to the CPT theorem, this also implies the violation of combined charge-conjugation and parity-inversion (CP) symmetry, making EDMs powerful tools for probing physics beyond the current Standard Model (SM) of particle physics. The muEDM experiment aims at setting the ground for a new direct electric dipole moment (EDM) search using muons. The experiment will perform this dedicated search using the frozen-spin technique for the first time worldwide, aiming at improving the current sensitivity by more than three orders of magnitude to better than 6 × 10−23 e cm, an astonishing jump. This search is a unique opportunity to probe previously uncharted territory and to test theories Behind Standard Model physics. The experiment will be performed in two phases. Phase I: In this exploratory phase, we will set up an experiment to demonstrate the frozen-spin method and search for a muon EDM using an existing solenoid. The instrument will be connected to a surface-muon beamline at PSI, delivering about 4e6 s−1 muons with a momentum of p=28 MeV/c. Although the sensitivity to a muon EDM will be sufficient to improve the current best measurement, the main purpose is to establish all necessary techniques and methods for a measurement with the highest possible sensitivity. Phase II: The future instrument will use a dedicated magnet with minimal field gradient between injection and storage region to increase the acceptance phase space and integrate all lessons …

Speaker: Tommaso Spadaro (Istituto Nazionale di Fisica Nucleare) The PADME experiment at the Frascati National Laboratory of INFN has performed a search for the hypothetical X17 particle, by observing the product of the collisions of the positron beam from the DAΦNE LINAC on a diamond fixed target. The beam energy has been varied in the range 265–300 MeV, corresponding to values of √s between 16.4 and 17.5 MeV, completely covering the center of mass region identified by the ATOMKI collaboration as significant for observing the postulated X17 particle. In my talk I will present the result of the analysis of these data, and briefly discuss the physics potential of the forthcoming PADME run, with an improved detector.

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: 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: 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 …