Tag Archives: Evento scientifico

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 …

Despite its great success, the Standard Model of particle physics has significant limitations. It does not account for the observed imbalance between matter and antimatter in the Universe, it cannot explain the nature of dark matter and dark energy, and it fails to incorporate gravity. Many extensions of the Standard Model, including models of dark matter, predict the existence of new particles with sub-MeV masses, interacting very weakly with ordinary matter. These particles could manifest through violations of discrete or Lorentz symmetries, temporal variations in fundamental constants, new forces, or as candidates for dark matter and dark energy. Precision experiments at low-energy and medium-scale facilities hold the potential to detect these phenomena. This workshop aims to foster collaborative approaches to low-energy tests of new physics in microwave, optical, atomic, nuclear, and condensed matter systems.  

Speaker: Atsushi Tokiyasu (Tohoku University, Japan) At the Research Center for Accelerator and Radioisotope Science (RARiS) in Japan, research in nuclear and hadron physics is conducted using low-energy electron beams and high-energy photon beams. This presentation will introduce our recent achievements, including the observation of a dibaryon state—a bound state of two Δ particles—and the precise measurement of the proton’s radius via electron scattering in the ULQ2 project. RARiS also participates in collaborative experiments at SPring-8/LEPS2, where high-energy photons generated through inverse Compton scattering are used in hadron physics research. In this experiment, we employ two detector systems: the LEPS2-solenoid spectrometer and the BGOegg electromagnetic calorimeter. We have recently completed the first phase of data collection and are currently analyzing the results. Our primary goal is to search for the K^−pp bound state via photoproduction. This talk will provide an overview of our activities, highlighting the role of photon beams in advancing nuclear and hadron physics in Japan. Additionally, I will discuss future directions at RARiS and explorepotential new research initiatives in this field.

Speaker: Giuseppe Gagliardi (Istituto Nazionale di Fisica Nucleare) The FNAL collaboration has measured the value of the muon anomalous magnetic moment, achieving an unprecedented precision of 0.2 ppm. From the theoretical perspective, it is crucial to match this experimentalprecision. The most challenging part of the theoretical calculation comes fromthe leading hadronic vacuum polarization (HVP) contribution Undefined control sequence \rmHVP, which must be determined with subpercent precision. In this seminar, I will review the latest lattice QCD results for, as well as for the subleading hadronic light-by-lightcontribution, and discuss the phenomenological impact of these results.

Speaker: Giacomo Ferrante (Montpellier University) Due to the infamous quadratic sensitivity of their masses to the UV scale, it is notoriously difficult to realise models where elementary scalar fields are light. Accidentally light scalars provide us with an interesting alternative to the wellknown cases of Nambu-Goldstone bosons (NGBs) and pseudo-NGBs. In models with spontaneous symmetry breaking by scalar fields in large group representations, we observe that some of the scalar masses can be loop-suppressed, even though there is no obvious symmetry argument preventing them from being generated at the tree-level. I will present the most minimal model, the SU(2) five-plet, with such accidentally light scalars, featuring compact tree-level flat directions lifted by loop corrections. I will sketch some potential applications, focusing, in particular, on constructing a model of hybrid inflation where the inflaton is an accidentally light scalar. This provides a robust realisation of hybrid inflation where the potential is naturally flat and protected from radiative corrections. At the end of inflation, tachyonic instability leads to the production of gravitational waves which, for a low inflationary scale, might be detected by upcoming experiments. Simple variations of the model can give rise to topological defects, such as unstable domain walls. Their dynamics produces a stochastic gravitational-wave background, which can be compatible with the recent detection by pulsar timing arrays.

Speaker: Kristjan Müürsepp (NICPB, Tallinn, Estonia) A pseudo Nambu-Goldstone boson (PNGB) coupled to a confining gauge group via an anomalous  term is characterised, during the confining phase transition, by a temperature dependent mass. I will study the possibility that a PNGB  coupled to a hidden gauge group  undergoing confinement  at a temperature different from the QCD  confining temperature could hit a level crossing with the QCD axion. This can  trigger axion-dark axion conversion. After describing the dynamics of the two axion system, I will address possible applications in cosmology.

Speaker: Oton Vazquez Doce (Istituto Nazionale di Fisica Nucleare) The study of three- and many-body dynamics has been a long-standing goal in nuclear physics, particularly for understanding the structure of light nuclei and describing neutron-rich and dense nuclear matter. In this seminar, a new experimental method to study three-body nuclear systems by measuring correlations in the momentum space of deuteron-hadron pairs produced in proton-proton collisions at the LHC is presented. The ALICE Collaboration has performed measurements of the Kaon-deuteron and proton-deuteron correlations analyzing high-multiplicity proton-proton collisions at sqrt(s) = 13 TeV [1]. The correlation functions are compared with effective two-body calculations anchored to results from Kaon-deuteron and proton-deuteron scattering experiments that provide an excellent description of the measured Kaon deuteron correlation but fail to describe the proton-deuteron system. This discrepancy can only be resolved by performing a full three-body calculation that accounts for the underlying three-nucleon dynamics. The analysis demonstrates that nucleons are the explicit degrees of freedom also in the correlations among light nuclei produced at short distances in hadronic collisions and opens the possibility of investigating the effect of genuine many-body nuclear interactions at the LHC in the future, including systems with strangeness and charm. [1] ALICE Collaboration, Phys. Rev. X 14, 031051 (2024)

This workshop will focus on the continuing development of the scientific case for a 22 GeV upgrade to CEBAF made possible by recent novel advances in accelerator technology. CEBAF’s envisioned capabilities, at the highest luminosities, will enable exciting opportunities that give scientists the full suite of tools necessary to comprehensively understand how QCD builds hadronic matter in the valence region. Through this workshop, JLab and its user community will continue to build the science case with descriptions and concrete projections for experiments that would become possible with an upgrade. We encourage our users and others interested to submit talks and ideas on the scientific topics listed below. Physics Topics: Charmed and light hadron spectroscopy Structure of hadrons: Form Factors, Parton Distribution Functions, TMDs, GPDs, Fragmentation Functions, Fracture Functions QCD in Nuclei and associated Nuclear Modifications and Dynamics Low energy tests of the Standard Model and physics beyond the Standard Model