Conveners
Nuclear, Particle- & Astrophysics (TASK - FAKT): I: LHC Physics and Theory
- Mauro Donega (ETH Zurich (CH))
- Anna Sfyrla (Universite de Geneve (CH))
Nuclear, Particle- & Astrophysics (TASK - FAKT): II: Muon
- Anna Soter (ETH Zürich)
Nuclear, Particle- & Astrophysics (TASK - FAKT): III: Low Energy and Antimatter
- Eberhard Widmann (Austrian Academy of Sciences (AT))
Nuclear, Particle- & Astrophysics (TASK - FAKT): IV: Detector / DAQ and Algorithms
- Paolo Crivelli (ETH Zurich (CH))
Nuclear, Particle- & Astrophysics (TASK - FAKT): V: Collider Dark Sector and Neutrinos
- Vitalii Lisovskyi (EPFL - Ecole Polytechnique Federale Lausanne (CH))
Nuclear, Particle- & Astrophysics (TASK - FAKT): VI: Dark Matter and Neutrinos
- Ben Kilminster (University of Zurich (CH))
The discovery of the Higgs boson at the LHC has opened a whole new chapter of exploration in particle physics, and the measurement of the Higgs boson couplings to second generation fermions is one of the next milestones of the LHC physics program. The associated production of a Higgs boson and a charm quark (c+H) is sensitive to the Higgs-charm coupling, and is yet to be probed experimentally...
I will present a test of lepton flavour universality performed using charm hadron $D^{+}_{(s)}\rightarrow \pi^{+} \phi(\ell^{+}\ell^{-})$ decays, with $\ell$ indicating either an electron or a muon. This measurement, performed using $5.4 \mathrm{fb}^{-1}$ of data collected by the LHCb experiment, validates our understanding of detection efficiencies of low momentum leptons. The clean...
Measurements of $b \to s\mu\mu$ during the last decade show a consistent pattern of deviations with respect to Standard Model (SM) predictions across a large set of observables in various decay modes. The branching fraction measurement of $B^0 \to K^{*0}(892)(\to K\pi)\mu^+\mu^-$, which includes the well studied $K^{*0}(892)$ resonance, show an abundance in the theory predictions with respect...
What is the minimal viable renormalizable SU(5) GUT with representations no higher than adjoints? In this talk I discuss an SU(5) model in which vectorlike fermions $5_F$+$\overline5_F$ as well as two copies of $15_H$ Higgs fields are introduced in order to accommodate for correct charged fermion and neutrino masses and to reproduce the matter-antimatter asymmetry of the universe. The...
Recently, a number of tensions has been observed in semileptonic decays of B hadrons to a lighter hadron and two leptons. With the large dataset collected by the LHCb experiment, it becomes possible to study higher-order processes. Emission of a virtual photon from the initial (final) state can create an additional dilepton pair, leading to a final state with four leptons. The experimentally...
We search for the $B^+ \to K^+ \tau^+ \tau^-$ decay using data collected by the LHCb experiment, reconstructing the $\tau$ leptons in $\tau^+ \to \pi^+ \pi^- \pi^+ (\pi^0) \bar{\nu}_{\tau}$.
This decay is produced in electroweak penguin loop transitions, highly suppressed in the standard model.
New models explaining the tensions observed in $b \to s l^+ l^-$ and $b \to c l \bar{\nu}$...
Gauge/Gravity duality has led to novel insights in the strong coupling behaviour of large $N_c$ QCD. Most notably is the type IIA supergravity construction by Witten, which was extended by Sakai and Sugimoto to include chiral quarks. This setup enables one to study interactions between glueballs, mesons and photons in an almost parameter-free manner. After giving a brief introduction to the...
Rare kaon decays are among the most sensitive probes of both heavy and light New Physics. In particular, the Ks->pipimumu process is of O($10^{-14}$) in the SM, and can be enhanced by up to a 100 times by exotic BSM models. Unlike the challenges faced by feasibility studies of $K_S\to\pi^+\pi^- e^+e^-$ decays due to the presence of electrons, $K_S\to\pi^+\pi^-\mu^+\mu^-$ is expected to be very...
Precision measurements of nuclear charge radii provide important inputs for modern nuclear theory, helping to improve our understanding of nuclear forces. The spectroscopy of muonic atoms is known as a highly precise method for such measurements. However, in the case of low- to medium-Z nuclei, the covered energy range has so far been difficult to access using laser spectroscopy or...
At the Paul Scherrer Institute we are setting up an experiment to search for the muon EDM. This talk focuses on the off-axis injection of the muons into a $3T$ storage solenoid. The injection channel needs to be magnetically shielded, so muons can pass from the exit of the beamline, low magnetic field region, into the high magnetic field region of the solenoid. In the fringe magnetic field,...
MuX, an experiment running at PSI, aims to measure the nuclear charge radius of radioactive isotopes, such as $\mathrm{^{226}Ra}$ and $\mathrm{^{248}Cm}$, using muonic atoms. With safety regulations imposing the usage of only microgram quantities of radioactive material the standard method to form a muonic atom by direct muon capture cannot be implemented. A technique that employs muon...
The potential discovery of non-zero electric dipole moments (EDMs) of leptons implies Charge-Parity violation beyond the Standard Model. This makes the experimental search for lepton EDMs a valuable tool to test scenarios explaining observations like matter-antimatter asymmetry, non-zero neutrino masses, and dark matter. A dedicated experimental search for the muon EDM is underway at PSI using...
The muEDM Collaboration is searching for the muon EDM by implementing, for the first time, the frozen-spin technique [Farley et al. (2004), PRL:93:052001]. A factor 1000 improvement upon the current limit $d_\mu<1.8\times10^{-19}\,e\mathrm{cm}\,\,(95\%\,\,\mathrm{C.L.})$ [Bennett et al. (2009), PRD:80:052008] is expected from this approach. A sub-microsecond trapping scheme is...
At the Paul Scherrer Institute we are developing a high precision instrument to measure the electric dipole moment (EDM) of the muon using the frozen-spin method to suppress the anomalous precession of the muon spin. With this technique, the expected statistical sensitivity for the EDM after one year of data taking is $6 \times 10^{-23}~e\cdot\mathrm{cm}$.
Reaching this goal necessitates a...
The existence of a neutron electric dipole moment (nEDM) would simultaneously violate parity and time symmetries, representing an additional channel of charge-parity violation. Therefore, it is an excellent testing ground for physics beyond the Standard Model (BSM). The international nEDM collaboration is currently commissioning the n2EDM experiment at the ultra cold neutron (UCN) source at...
The n2EDM experiment at the Paul Scherrer Institut searches for a permanent neutron electric dipole moment. For the purpose of correcting magnetic field fluctuations in its setup, a laser-based $^{199}$Hg co-magnetometer has been developed. The optical pumping of the $^{199}$Hg atoms (I=1/2) with a UV laser leads to the nuclear spin polarization. The laser is also used to extract the spin...
In the search for the neutron electric dipole moment, we are setting up the n2EDM experiment (Eur. Phys. J. C 81, 512 (2021)) at the ultracold neutron (UCN) source at PSI. We created a new, efficient UCN guide system to transport neutrons from the source to the experiment. The UCN guides are made of glass and highly polished aluminium, and are coated inside with a nickel-molybdenum alloy for...
The search for the neutron electric dipole moment at PSI requires a stable, uniform magnetic field environment in the experimental chamber. To shield the n2EDM-experiment from slowly varying magnetic fields caused by neighbouring experiments we have constructed an intricate system of coils around the experiment, designed to compensate magnetic fields through an active feedback loop. The design...
Ultracold Neutrons (UCN) provide a unique tool for fundamental low energy
particle physics and in particular measurements with neutrons with long
observation times. The τSPECT experiment, which has been developed and built at Johannes Gutenberg University Mainz, Germany, and is currently being set up at the UCN source at Paul Scherrer Institute, aims to utilize this fact in order to...
The GBAR collaboration at CERN aims to directly test the Weak Equivalence Principle with a free fall of ultracold antihydrogen $\mathrm{\overline{H}}$ in Earth's gravitational field. The main principle is to first produce an antihydrogen ion $\mathrm{\overline{H}^+}$ and sympathetically cool it to $\mathrm{\mu K}$ temperature. The excess positron is then photodetached and the neutral anti-atom...
At very low energies, an atom above a horizontal surface can experience quantum reflection due to the attractive Casimir-Polder potential. The quantum reflection holds the atom against gravity and leads to quantum gravitational states (GQS), in analogy to what has been observed with ultracold neutrons.
The GRASIAN-collaboration pursues the first measurement of GQS of atomic hydrogen. The use...
Several approaches have been proposed for modelling antiproton-nucleus annihilation at rest, but a complete description of the process is still lacking, as well as systematic data. This talk focuses on recent experimental results from annihilation measurements at the ASACUSA experiment, using slow extracted antiprotons and targets of 1-2 μm thickness. The prongs from individual annihilation...
The Hybrid seeding is the standalone reconstruction algorithm of the forward tracker at LHCb, originally designed to run on CPUs at a 1MHz throughput. We will explore how, through reformulations and better memory handling, a version of this algorithm is now a core part of the 30 MHz LHCb GPU-based trigger. In this presentation, we will discuss the main takeaways of this challenging endeavour...
Triggering forward electron and photon candidates in high-energy physics experiments is difficult where no tracking information is available and one has to rely only on calorimetric endcap detectors . It becomes even more challenging in extreme pile-up conditions as they will be faced by the experiments at CERN in Run 4 after the High Luminosity LHC upgrade. The all-purpose Geant4 based...
We studied the radiation induced damage of the SiPM photo-detectors of the LHCb SciFi Tracker during the first year of Run 3. The bias current monitoring allows to evaluate the Dark Count Rate (DCR) and leads to an estimation of the detector aging as a function of the integrated luminosity. During the YETS the detector was monitored at room temperature and the effect of annealing (reduction of...
The proposed next-generation dark matter experiment DARWIN, an underground multi-tonne scale detector with a time projection chamber at its core, aims to reach unprecedented sensitivities in probing further into the WIMP parameter space and other new physics interactions, such as neutrinoless double beta decay. To achieve these ambitious goals, extensive R&D campaigns are currently in...
The DARWIN project aims to establish a next-generation observatory for the detection and study of dark matter and neutrinos, featuring a 50-tonne dual-phase xenon time projection chamber. As a full-scale demonstrator, the Xenoscope facility at the University of Zurich investigates its technological challenges. A key focus is the search for ultra-low background photosensors capable of detecting...
Looking for beyond Standard Model phenomena, Mu3e is an experiment under construction at PSI dedicated to the search of the charged lepton flavor violating mu->eee decay at branching fractions above $10^{-16}$. Achieving such sensitivity requires a high rate of muons and excellent time resolution to suppress the accidental background. To this end, the scintillating fiber (SciFi) sub-detector...
The FASER experiment at the LHC will be instrumented with a high precision W-Si preshower to identify and reconstruct electromagnetic showers produced by two O(TeV) photons at distances down to 200µm. The new detector features a monolithic silicon ASIC with hexagonal pixels of 100µm pitch, extended dynamic range for the charge measurement, and capability to store charge information for...
After Run III the ATLAS detector will be upgraded to cope with the harsher radiation environment and increased number of proton interactions in the high luminosity LHC. One of the key projects in this suite of upgrades is the ATLAS Inner Tracker (ITk). The Pixel Detector of the ITk must be read out accurately and at an extremely high rate and for this it relies on the Optosystem, which...
The SST-1Ms are two single-mirror small-sized telescope prototypes developed by a team of Swiss, Polish and Czech institutes. The telescopes adopt a Davies-Cotton optical design, with a dish of 4 m diameter and a focal of 5.6 m. With a wide field of view of 9 degrees, SST-1M is designed to detect gamma rays in the energy range between 500 GeV and 100 TeV.
SST-1M is equipped with the DigiCam...
The MONOLITH ERC Advanced project aims at producing a monolithic silicon pixel ASIC with 50µm pixel pitch and picosecond-level time stamping. The two main ingredients of the project are fast and low-noise SiGe BiCMOS electronics and a novel sensor concept, the Picosecond Avalanche Detector (PicoAD).
Testbeam measurements of the proof-of-concept PicoAD prototype show full efficiency and time...
The Dark Sector is a collection of hypothetical particles that would interact very weakly with Standard Model particles. Thanks to its forward instrumentation and its excellent vertex resolution, the LHCb experiment plays a unique role in the search for Dark Sector particles at LHC. Some results from searches for hidden-sector particles (e.g. dark photons, heavy neutral leptons and dark matter...
Beyond the minimal kinetically-mixed dark photon scenarios predicting fully visible and fully invisible mediator decays, next-to-minimal theories have been considered as compelling frameworks for thermal dark matter and some low-energy anomalies, as the muon g-2.
This talk will showcase the potential of the NA64 experiment in the exploration of rich dark sectors in which the dark photon is...
NA64 is a fixed-target frontier experiment running at the CERN SPS. NA64 searches for possible candidates of mediators between the dark sector and the standard model by looking for missing energy events in an active beam dump. After resuming data taking in 2021, NA64 has tripled its statistics, allowing us to set leading constraints to dark sector mediators in the light dark matter parameter...
In 2016 the ATOMKI collaboration measured an anomaly in the angular distribution of the pair produced by the M1 transition of the isoscalar 1+ state on 8Be, which might be explained by creation and decay of a boson, the X17, with mass 17.0 MeV/c2. The result was later confirmed in the 0-/0+ transition in Helium.
The apparatus of the MEG II experiment has been employed at the beginning of...
SND@LHC is a compact stand-alone experiment designed to study neutrinos produced at the LHC. The detector consists of a hybrid target made of emulsion cloud chamber walls interleaved with scintillating fibre planes, followed by a hadronic calorimeter and muon system based on scintillating bars. The active detectors are read out with silicon photomultipliers and custom electronics that allow...
The SND@LHC is a recently approved and running experiment at the Large Hadron Collider (LHC) performing neutrino physics and searches for feebly interacting particles. It collects human-made neutrinos in the uncharted TeV energy scale from pp collision at the ATLAS interaction point. This talk will focus on the first physics result of the experiment, namely the observation of collider...
FASERnu, in the LHC-FASER experiment at CERN, studies collider neutrinos. It consists of 730 alternating emulsion films and tungsten plates, resulting in a target mass of 1.1 tonnes. Data-taking began in 2022, and will continue until the end of 2025. In 2022, due to the track occupancy in emulsion, three data-taking periods were successfully carried out, each requiring darkroom assembly and...
The LEGEND experiment is designed to detect lepton-number violation and shed light on neutrino masses by hunting for neutrinoless double beta decay. The experiment employs high-purity, enriched in $^{76}$Ge germanium detectors and an active liquid-argon shield to minimize background events. In the first phase, the experiment will use 200 kg of Ge crystals to reach a half-life discovery...
Deep learning methods are becoming key in the data analysis of particle physics experiments. One clear example is the improvement of neutrino detection using neural networks. Current neutrino experiments are leveraging these techniques, which, in combination, have exhibited to outperform standard tools in several domains, such as identifying neutrino interactions or reconstructing the...
Neutrino physics is a field of high energy physics measuring neutrino properties, such as cross sections, masses, and oscillation parameters. Currently, the field lies at a crossroads. A new generation of neutrino experiments, such as DUNE and Hyper-K, are planned in the following decades, requiring significant resources in detector design and construction efforts. Additionally, physicists...
XENONnT is a direct dark matter search experiment located at Laboratori Nazionali del Gran Sasso in Italy. Due to its unprecedentedly low background and the large target mass of 5.9 tonnes of liquid xenon in a dual-phase time projection chamber, it is sensitive to a wide range of signals within and beyond the Standard Model. These include weakly interacting massive particles, solar axions,...
The long-awaited detection of dark matter is dependent upon the design of sufficiently large, radio-pure and sensitive detectors. DARWIN is a next-generation dark matter observatory which will probe the accessible parameter space for WIMPs. It will comprise a dual-phase time projection chamber containing 40 t of liquid xenon. Ultra-low background levels are ensured by the selected...
The DARWIN observatory is a proposed next-generation experiment for dark matter detection and neutrino physics. Darwin will feature a 50-ton liquid xenon target enclosed in a dual-phase time projection chamber. The realization of this multi-ton scale detector requires addressing a series of technological challenges; to this end, a full-scale vertical demonstrator, Xenoscope, was built at UZH....
We present a detailed density functional theory (DFT) study of the electronic structure of atomic and liquid xenon, as a first step in quantifying the event rates in operating xenon-based detectors based on dark matter (DM) - electron scattering. Our main goal is to determine whether explicit modelling of the inter-atomic interactions in the liquid state changes the predicted event rates...
The DAMA/LIBRA experiment has been reported to observe an annually modulating signal compatible with the expected dark matter (DM) event rate for more than two decades. However, these results have not been confirmed by any other direct DM searches, emphasizing the need for a model-independent validation using the same detector material: sodium iodide(NaI) crystals. Cryogenic Observatory for...
The NUSES space mission is a novel project based on a satellite developed by TAS-I housing two payloads known as TERZINA and ZIRÈ. ZIRÈ is designed to explore low-energy cosmic rays and gamma rays for instance from gamma-ray bursts. ZIRÈ will conduct measurements of electrons, protons, and light nuclei ranging from a few to hundreds of MeV and new tools for detecting cosmic MeV photons and...
Muonium, the purely leptonic bound state of an anti-muon and an electron, is an excellent candidate to probe bound state QED and search for new physics beyond the Standard Model. I will introduce MuMASS, aiming to improve the Muonium 1S-2S transition by three orders of magnitude. I will present our latest experimental progress and results, touching on the New Physics reach of the measurements,...
