PRISMA Colloquium

The precision measurement of the top-row Cabibbo-Kobayashi-Maskawa (CKM) matrix element $V_{ud}$ from beta decays of pion, neutron and nuclei plays an important role in low-energy precision tests of Standard Model (SM) predictions. The recent observation of an apparent deficit of the top-row CKM unitarity has attracted wide attentions and provided hints for physics beyond the Standard Model (BSM). Higher precision for the $V_{ud}$ extraction is needed to confirm (or reject) such an observation; in this talk the referent will discuss some ongoing efforts from the theory and experimental side to achieve this goal.
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In extreme astrophysical environments like supernova explosions, the large neutrino density can lead to collective flavor oscillations driven by neutrino-neutrino interactions. These phenomena are important to describe flavor transport and have potentially important consequences for both the explosion mechanism and nucleosynthesis in the ejected material. Even simple models of neutrino-neutrino interactions require the solution of a challenging many-body problem whose exact solution requires exponential resources in general. In this talk the referent will describe the physics of collective flavor oscillations and present the recent efforts to simulate the real-time flavor dynamics of two-flavor neutrinos using current generation quantum computers based on both superconducting qubits as well as trapped ions.

The latest measurement of the muon g-2 announced at Fermilab exhibits a 4.2$\sigma$ discrepancy from the currently accepted Standard Model prediction. The main source of uncertainty on the theoretical value is represented by the leading order hadronic contribution $a_{\mu}^{HLO}$, which is traditionally determined through a data-driven dispersive approach. A recent calculation of $a_{\mu}^{HLO}$ based on lattice QCD is in tension with the dispersive evaluation, and reduces the discrepancy between theory and experiment to 1.5$\sigma$. An independent evaluation of $a_{\mu}^{HLO}$ is therefore required to solve this tension and consolidate the theoretical prediction. The MUonE experiment proposes a novel approach to determine $a_{\mu}^{HLO}$ by measuring the running of the electromagnetic coupling constant in the space-like region, via $\mu-e$ elastic scattering. The measurement will be performed by scattering a 160 GeV muon beam, currently available at CERN's North Area, on the atomic electrons of a low-Z target. A Test Run on a reduced detector is planned to validate this proposal. The status of the experiment in view of the Test Run and the future plans will be presented.
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Evaluations and selections determine scientific careers possibly like no other factor. Knowing that they are also susceptible to bias and preconceptions, how can we ensure a fair recruitment process and assure to pick the best candidate? Together, we want to reflect how we hold discussions in selection committees (on all career levels!) and learn what practices prove helpful in guaranteeing more equitable opportunities for all applicants. Please register through prisma@uni-mainz.de to receive preparatory material.
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What happens when gold nuclei, accelerated to about 90% of the speed of light, strike gold nuclei at rest? For an extremely short time, t~10^-23 seconds, states of matter at extreme temperatures (10^12 K) and densities (>280 Mt/cm^3) are produced. The microscopic properties of the strong-interaction matter under extreme conditions of temperature and density is a topic of great current interest. Despite 18 orders of magnitude difference in system size and time, the conditions present in heavy-ion collisions share great overlap with the conditions of the strong-interaction matter in neutron-star mergers. The possibility to form and explore in the laboratory strong-interaction matter under extreme conditions is truly fascinating. The Compressed Baryonic Matter (CBM) experiment at FAIR has the potential to discover the most prominent landmarks of the QCD phase diagram expected to exist at high net baryon densities. The measurement of comprehensive set of diagnostic probes offers the possibility to find signatures of exotic phases, and to discover the conjectured first order deconfinement phase transition and its critical endpoint. In this talk the referent will focus on relevant observables to study criticality, emissivity, vorticity and equation-of-state of baryon rich matter. Particular emphasis is put on rare probes which are not accessible by other experiments in this energy range.

The referent will describe some recent work on applying Effective Field Theory (EFT) methodology to three different physically interesting systems. First he will explain the philosophy and general methodology of EFT. He will then present three short vignettes. The first has to do with techniques for systematically computing the EFT parameters from a given more fundamental description. The second will show how EFT can be used to understand the behavior of quantum fields in an inflationary background, with applications to light scalar fields and the inflaton itself. And in the third, the referent will show how EFT ideas can be applied to systematically improve a numerical technique for quantum field theory known as Hamiltonian truncation.
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With the establishment and maturation of the experimental programs searching for New Physics with sizeable couplings at the LHC, there is an increasing interest in the broader particle and astroparticle community for exploring the physics of light and feebly-interacting particles (FIPs) as a paradigm complementary to a New Physics sector at the TeV scale and beyond. SHADOWS is a new experiment proposed at the CERN North Area to search for a large variety of FIPs produced in the interactions of a proton beam with a dump. It will use the 400 GeV primary proton beam extracted from the CERN SPS currently serving the NA62 experiment. SHADOWS can expand the exploration for a large variety of FIPs well beyond the state of the art in the MeV-GeV mass range which is allowed by cosmological and astrophysical observations and become one of the main players in the search for FIPs at accelerators in the next decade. After an introduction about the current plans for searching for FIPs at CERN within the Physics Beyond Colliders activity the referent will present the status of the SHADOWS project.
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The European Spallation Source, ESS, currently under construction in Lund, will be the world’s most powerful facility for research using neutrons. Supported by 3MEuro Research and Innovation Action within the EU Horizon 2020 program, a design study (HighNESS) is now underway to develop a second neutron source below the spallation target. Compared to the first source, located above the spallation target and designed for high cold and thermal brightness, the new source will provide a higher intensity (the total number of neutrons from the moderator), and a shift to longer wavelengths in the spectral regions of Cold (4-10 ˚A), Very Cold (10-100 ˚A), and Ultra Cold (> 500 ˚A) neutrons. The core of the second source will consist of a large liquid deuterium moderator to deliver a high flux of cold neutrons and to serve secondary VCN and UCN sources, for which different options are under study. The features of this new source will boost several areas of condensed matter research and will also provide unique opportunities in fundamental physics with the neutron antineutron oscillations experiment NNBAR. This experiment will search for the baryon number violating process of n → ¯n oscillation with a sensitivity of three orders of magnitude over the previously attained limit obtained at the Institut Laue-Langevin ILL. As a part of the HighNESS project work is ongoing to deliver the Conceptual Design Report of the experiment. Concerning the design of the Ultra Cold Neutron and Very cold neutron source for the ESS, a digital workshop has been held from February 2nd to February 4th, 2022 where experts from various laboratories and Universities have gathered to propose and discuss ideas and challenges for the development of these sources. During the course of the workshop, several possibilities have been identified on where to locate the VCN and UCN sources. The UCN source could be placed in close vicinity or at some distance from the primary cold source. Regarding the VCN source, we have identified two possibilities. In the first option, the VCNs are extracted from the main CN source using advanced reflectors. While in the other case we make use of a dedicated VCN converter, for which a material capable of delivering a high flux of VCNs is needed. From the point of view of neutronic performance, two promising materials, which are under study in the HighNESS project, are solid deuterium at about 5 K and deuterated clathrate hydrates at around 2 K. In summary in the the talk, the referent will discuss the HighNESS project, the status of the NNBAR experiment and all the possibilities for a dedicated UCN and VCN source at the ESS.
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The neutrino discovery (1956), by Reines & Cowan, paved the technical ground behind the establishment of much of today’s neutrino detection. Large instrumented volumes have been achieved via a key (implicit) principle: the impeccable transparency of detector, almost regardless of detection technique.Much of that technology has yielded historical success, including several discoveries and Nobel prizes, such as that of 2015 for the discovery of the Neutrino Oscillation phenomenon leading to an important modification of the Standard Model of Particle Physics. Despite their remarkable success, much of the transparent-based technology is also known to suffer from some key limitations, even after 70 years of maturity towards perfection. The pending challenge is to be to endow detectors with powerful active background rejection while allowing large volume articulation. Indeed, poor particle identification is a long standing issue. This forces experiments to rely on expensive and cumbersome external shield (active or passive), including major overburden in underground laboratories, as the only mean to mitigate otherwise overwhelming backgrounds. In this seminar, the referent shall introduce the LiquidO technology — in final stages of demonstration — relying, for the first time, heavily on detection medium opacity. The goal is enable sub-atomic particle event-wise imaging, so event topology may be use for particle ID purposes, even in the low MeV region. The development is led by the homonymous LiquidO international academic consortium with institutions over 10 countries. While not perfect, LiquidO appears to be capable to offer several detection features that might lead to breakthrough potential in the context of both neutrino and rare decay physics. The physics potential will be briefly highlighted. Beyond its most basic demonstration, LiquidO remains a testbed context for further detection R&D, where much innovation is expected and ongoing.

The tentative detection of a few anti-Helium nuclei [1] is presently revitalising the discussion on the existence of baryonic antimatter in the Universe. As ”the discovery of a single anti-helium nucleus in the cosmic ray flux would definitely point toward the existence of stars and even of entire galaxies made of anti-matter” [2] it has been proposed that the anti-Helium nuclei could originate from anti-clouds or anti-stars in the solar vicinity [3]. We discuss possible entities of antimatter in the Universe that would be probed through ordinary matter, with annihilation-radiation providing indirect evidence for their presence [4]. The observations of high energy (∼ 100 MeV) gamma-rays sets limits on the fraction of nuclear antimatter contained in our local and Galactic neighbourhood. We review recent gamma-ray [5] observations that set upper limits on such emissions. [1] S. Ting, https://indico.cern.ch/event/729900, (2018) [2] P.Salati, et al., Nuclear Physics B, 70, 1-3, 492, (1999) [3] V. Poulin, et al., Phs. Rev. D 99, 023016, (2019) [4] P. von Ballmoos, Hyperfine Interact. 228, 91,, (2014) [5] S. Dupourque, et al., Phs. Rev. D 103, 083016, (2021)

Cosmologists are puzzled by a tension between the results of two categories of observations, which has been growing over the past few years. This “Hubble tension” arises from contradictory indications concerning the current expansion rate of the universe. The referent will try to give a pedagogical overview of this problem, with a summary of the physical assumptions that go into the interpretation of each observation. Then, assuming that the tension persists with future data releases, he will give examples of the kind of new fundamental physics that could help solving it.
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