Particle Physics Seminars I

Speaker: Liliana Apolinário

Title: Unveiling the time structure of QCD jets

Abstract: Heavy-ion collisions are a unique laboratory to recreate the high energy and density conditions prevalent during the primordial moments of our Universe: the Quark-Gluon Plasma (QGP). This new state of matter is made of the elementary building blocks (quarks and gluons) of Quantum Chromodynamics (QCD), a key ingredient of the Particle Physics Standard Model. Unveiling the characteristics of the QGP allows us to ascertain the QCD's fundamental properties. This goal can be achieved in hadronic collisions through jets: spray of particles that result from the fragmentation of high-energy quarks and gluons produced concurrently with the collision. The fact that jets in proton-proton collisions are well understood has allowed us to successfully use them to extract the QGP's time-averaged properties. However, jets are evolving multi-scale objects that witness the entire space-time evolution of the system, making them unique tools for analysing the strong time dependence of the QGP properties. In this talk, I will present the most recent breakthroughs that unlocked time-differential methods for a full time-scan of the QGP at current colliders' energies.

Speaker: Nuno Leonardo

Title: The LHC at the intensity frontier

Abstract: The LHC is our most powerful tool to probe nature at the smallest scales and most fundamental level. The strategy is to accumulate large datasets at high energies to search for tiny signals. One such signal was revealed a decade ago, and resulted in the experimental confirmation of the last standard model particle. While no new particles beyond the standard model have been established so far, there is tantalising evidence of their presence in the data. Namely, a persistent and significant pattern of deviations from the theory predictions has been revealed, the so-called flavour anomalies. I’ll present the exploration of rare signals around the flavour sector that we’ll continue to pursue at the LHC and beyond. Such exploration encompasses direct and indirect searches for new physics, with both general-purpose and dedicated detectors. In this context, I’ll also introduce the most recent CERN experiment, that we have just installed at the LHC, with the goal of observing collider neutrinos for the first time, and probing the anomalies in lepton universality. The broader goal is that of exploring the unmatched physics potential of the LHC to the fullest extent and into the intensity frontier we are now entering.

Speaker: João Penedo

Title: Piecing together the Flavour puzzle

Abstract: Despite its repeated successes, the Standard Model is not the last word in our understanding of the subatomic world. The peculiarities that set neutrinos apart from other particles hint at Neutrino Physics as the most promising gateway to Physics Beyond the Standard Model (BSM). In an era of precision, neutrino masses and mixing are fundamental pieces in the broader puzzle of Flavour.  From the theoretical and phenomenological viewpoint, one strives to find unified and testable descriptions of the known flavour patterns which address fundamental problems in Particle Physics -- e.g. the smallness and nature of neutrino masses, the nature of dark matter, the sources of matter-antimatter asymmetry and its absence in strong interactions. Such new Physics may justify tantalising anomalies in the data. The unprecedented sensitivities of upcoming experiments (e.g. DUNE, Belle and SHiP) will allow us to scrutinise these BSM scenarios and persistent deviations within the next decade.

Speaker: Andreas Trautner

Title: The Standard Model flavor puzzle and perspectives of a resolution

Abstract: With decades worth of data from high precision flavor experiments and robust confirmation at the LHC, addressing the Standard Model flavor puzzle is more pressing than ever. I will briefly, pedagogically introduce the puzzle then discuss my way to approach its resolution. This involves new mathematical techniques, for example, to understand the violation of matter-antimatter symmetry, as well as new model building extensions (including multi-Higgs models) to scrutinize experimental anomalies and the elementary structure of quarks, charged leptons and neutrinos. Most importantly, the dynamics of the flavor structure needs to be understood in order to reduce the number of necessary input parameters. This gives way to testable predictions not only at the LHC and future colliders but potentially also in the cosmological background radiation and high energy cosmic rays. Since all of this could be embedded in UV complete frameworks such as string theory, a correct model should reveal groundbreaking connections also to other important puzzles of modern particle physics such as the origin of neutrino masses, dark matter, or the unification of gauge interactions.