PRISMA Colloquium

Modern machine learning and artificial intelligence are starting to fundamentally change how we analyse huge volumes of data in particle physics and adjacent scientific disciplines. These breakthroughs promise new insights into major scientific questions such as the nature of dark matter or the existence of physical phenomena beyond the standard model. This colloquium will provide an overview of recent, exciting developments with a focus on model agnostic discovery strategies — including first experimental results, fast simulations, and foundation models that simultaneously solve multiple tasks across multiple data sets. Slides: https://drive.google.com/file/d/1PR2orzm-tn63oeV3IUxe1xLrnWulskcz/view?usp=sharing

Although experimentally well-established, the nature of the Lambda(1405) hyperon resonance has long been a mystery. Constituent quark models have difficulty accommodating its low mass, while approaches based on chiral effective theory typically predict an additional state, the Lambda(1380), which is broad and difficult to identify. I will present the first lattice QCD computation of the coupled-channel $\pi\Sigma-\bar{K}N$ scattering amplitude in the Lambda(1405) channel, which employs quark masses so that the $\pi\Sigma$ threshold is approximately 1380 MeV. This enables the unambiguous identification of the Lambda(1380) in addition to the Lambda(1405), thus supporting the exotic meson-baryon `molecule' interpretation.
Slides here...

Unfortunately, this talk had to be canceled due to unforeseen circumstances.

I will discuss how proton decay, combined with gravitational waves, can be used to test Grand Unified Theories (GUTs). In particular, proton decay searches by large multipurpose neutrino experiments such as DUNE, Hyper-Kamiokande, and JUNO will either discover proton decay or further push the symmetry-breaking scale above 10^16 GeV. Another possible observational consequence of GUTs is the formation of a cosmic string network produced during the breaking of the GUT to the Standard Model gauge group, which can produce a stochastic background of gravitational waves. Several gravitational wave detectors will be sensitive to this over a wide frequency range. I will demonstrate the non-trivial complementarity between the observation of proton decay and gravitational waves produced from cosmic strings in determining SO(10) GUT breaking chains and their compatibility with leptogenesis as a means of producing the observed matter-antimatter asymmetry. Additionally, I will extend this discussion to include supersymmetric GUTs, taking into account recent findings from Pulsar Timing Arrays that have detected gravitational waves in the nanoHertz frequency range.
Slides here...

The NA62 experiment at CERN is the worlds leading K+ laboratory, with the primary goal of studying the ultra-rare decay K+ --> pi+ nu nu. In the last few years several key upgrades have been implemented giving improved performance for our currently ongoing data-taking campaign. In this colloquium I will introduce the NA62 experiment and this golden decay mode, K+ --> pi+ nu nu, and the latest news on the analysis status. NA62 has a broad physics programme and I will also present the latest results from across our research programme, including hot-off-the-press rare and forbidden K+ decay searches.
Slides here...

The nature of dark matter is one of the most important open questions in modern physics. Astronomical and cosmological measurements provide strong evidence for its existence. Despite the many hypothetical candidate particles that have been proposed, experimental efforts have so far yielded only null results. Direct detection is a promising method for determining the nature of this dark component of the Universe. It allows, for example, to probe the existence of WIMPs (Weakly Interacting Massive Particles) via their elastic scattering off target nuclei down to tiny interaction cross sections. Several experimental strategies have been developed to measure the small recoil induced by dark matter interactions, with liquid xenon TPCs being one of the most successful. This talk will discuss the status and main results of XENONnT and outline future plans with the DARWIN/XLZD observatory.
Slides here...

Since neutrinos have no electric charges, they may be their own antiparticles, referred to as Majorana neutrinos, and thus violate lepton number conservation. Neutrinoless double beta decay would be a direct consequence, and the search for this decay mode is the most sensitive method to unravel the Majorana nature of neutrinos. By operating bare germanium diodes, enriched in Ge-76, in an active liquid argon shield, GERDA achieved an unprecedently low background index of 5.2∙10−4 counts/keV kg yr in the signal region and collected an exposure of 127 kg yr in a background-free regime. No signal was observed, and a limit on the half-life of 0νββ decay in Ge-76 is set at T1/2 > 1.8∙1026 yr (90 % C.L.) [1] and Majorana neutrino masses are constrained to mββ< 79–180meV (90\% C.L.). The LEGEND Collaboration builds on the success of GERDA and MJD, and develops a phased, Ge-76-based double-beta decay experimental program with a T1/2 - discovery potential beyond 1028 years. Its first stage, LEGEND-200, started data-taking in early 2023, and LEGEND-1000 is under preparation. The first results from LEGEND-200, based on 48.3 kg·yrs of data, were presented in June at the Neutrino 2024 conference in Milan and will be discussed.