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HEP Seminars & Vivas

18 Jun 2024

UCL HEP Seminars 2021

: Mario Campenelli

Forward detectors in ATLAS

While most of the particles produced in LHC collisions are emitted in the forward detectors, most of the physics program and detectors focus on high-pt small-rapidity production. But the ATLAS experiment (as well as CMS) has several detectors aiming at measuring particles emitted very close to the beam, covering a large class of measurements, different and complementary to those performed with only the central detectors. In this seminar I will describe the forward detectors from ATLAS, their goals, their current status and their use in past and future physics measurements.

: Elisabetta Pallante (Groningen)

Theory of the Muon g-2

I review the status of the theoretical prediction for the anomalous magnetic moment of the muon within the Standard Model of Particle Physics. Guided by a historical perspective, the seminar will cover physics and anecdotes from the first calculations to current efforts. I will discuss the challenges, strategies, status, and open questions of the Standard Model prediction. Is the discrepancy between the latter and current experimental results hinting at new physics?

: Melissa van Beekveld (Oxford)

SUSY wanted - dead or alive

Due to the null-results at the LHC in the search for supersymmetry (SUSY), there is a growing belief that the concept of SUSY is just another failed theory. In this talk, we will examine where this belief comes from. We will take a careful look at the fine-tuning problem, and see that the story is a lot more nuanced than often suggested. If time allows, we will also discuss the dark side of SUSY.

: Yoshi Uchida (Imperial)

CP-Violation: the next stop on our neutrino journey of discovery?

The field of neutrino oscillations has experienced several breakthrough moments over the past couple of decades, each time with a number of vastly different experiments coming together to point the way forward. The most recent breakthrough, from the T2K Experiment, shows that we are already able to start probing whether our description of neutrinos should include a significant CP-violating complex phase, something that even the most optimistic of us might not have bet too much on when we set out to build the experiment. As we enter a new era, with DUNE and Hyper-K—the next generation of very long-baseline experiments—well into construction, I will introduce the field of neutrino oscillations and our most recent results, how we got here and the challenges we face as we pursue the next breakthroughs that neutrinos have in store for us.

: Clara Barker (Oxford)

Scattering atoms, electrons and perceptions

In this talk I will discuss the state of equity and inclusion in the UK in the field of STEM, with examples from my own journey. I will discuss why it is something we should consider, how science can benefit from making STEM more equitable, and suggest some thinking points for bring about this change.

: Andy Buckley (Glasgow)

Accelerating physics impact: the why & how of Rivet analysis preservation

In a decade, the LHC experiments have issued over 3000 analysis papers, covering a huge spectrum of physics from soft QCD to myriad high-scale regions sensitive to hypothetical BSM physics. Central to the vast majority of these studies have been MC event generators, whose sophistication has also increased manyfold though the period of LHC operation. In this talk I'll review the ways in which the Rivet toolkit -- a key tool in this rise -- emerged from MC development and tuning, the development of its many hundreds of encoded analyses, through to its current leading-edge use as a powerful complement to BSM direct-searches in global fits of new physics. Whether your interest is QCD, electroweak, or BSM physics, I will show how the small amount of work in preparing a Rivet routine acts as a gateway to analysis re-use and greater physics impact.

: Giovanni De Lellis (Naples)

Collider neutrinos: the SND@LHC experiment at CERN

SND@LHC is a compact and stand-alone experiment to perform measurements with neutrinos produced at the LHC in a hitherto unexplored pseudo-rapidity region of 7.2<𝜂<9.6, complementary to all the other experiments at the LHC. The experiment is to be located 480 m downstream of IP1 in the unused TI18 tunnel. The detector is composed of a hybrid system based on an 800 kg target mass of tungsten plates, interleaved with emulsion and electronic trackers, followed downstream by a calorimeter and a muon system. The configuration allows efficiently distinguishing between all three neutrino flavours, opening a unique opportunity to probe physics of heavy flavour production at the LHC in the region that is not accessible to ATLAS, CMS and LHCb. This region is of particular interest also for future circular colliders. The detector concept is also well suited to searching for Feebly Interacting Particles via signatures of scattering in the detector target. The first phase aims at operating the detector throughout LHC Run 3 to collect a total of 150 fb−1. The experiment was recently approved by the Research Board at CERN. A new era of collider neutrino physics is just starting.

: Sneha Malde (Oxford)

Exploiting the strengths of the BESIII and LHCb experiments to make the most precise CKM angle gamma measurement

The BESIII and LHCb detectors – while both dedicated to flavour physics are different in collision energy, collision particle, geometry and size. Nonetheless in the quest to understand the Standard Model or potential new physics models they both play an important role. BESIII has the largest sample of quantum-correlated decays of the Psi(3770) meson – useful for measurement of the seemingly obscure charm strong-phase parameters. However, these are vital for studies at LHCb where their combination with the huge B decay samples leads to the most precise measurement of the CKM angle gamma. In this talk I will describe the significant developments over the last 18 months in this sector and discuss the leading measurements at both experiments.

: Mitesh Patel (Imperial)

Update on the B-anomalies

I will give an update on the so-called B-anomalies, focussing on the recent evidence for lepton flavour universality breaking from the LHCb experiment.

: Liz Kneale (Sheffield)

WATCHMAN: Project Overview and New Techniques for Reactor Antineutrino Detection

Monitoring known nuclear reactors and identifying an unknown nuclear reactor in a complex nuclear landscape is challenging. WATCHMAN will demonstrate for the first time a scalable anti-neutrino detector for mid- to far-field nuclear non-proliferation applications. In this talk, I will discuss the nuclear power-weapons connection and the proposed WATCHMAN anti-neutrino detector and remote reactor monitor prototype, before going on to show how using new and updated reconstruction and analysis methods can improve anti-neutrino signal detection and background suppression to optimise the sensitivity of Gd-doped water Cherenkov detection for remote reactor monitoring.

[recording]

: Paolo Franchini (Imperial)

The Muon Ionization Cooling Experiment and the muon ionization cooling demonstration

Future muon colliders can study lepton-antilepton collisions up to several TeV while neutrino beams produced in neutrino factories from stored beams will have an unique precision in measuring neutrino oscillations. Both muon colliders and neutrino factories will require intense muon sources with low emittance. Muons produced from decays of pions (created in proton-target interactions) occupy a large phase space which makes difficult the acceleration and storage of the beam. Cooling techniques like stochastic cooling (successfully used for protons at CERN) do not prove to be efficient methods due to the short lifetime of the muons. Ionization cooling, proposed in the late '60s and only recently demonstrated by MICE (Muon Ionization Cooling Experiment) consists in reducing the amplitude of the muon beams, passing the muons through an absorber in order to remove part of the transverse and longitudinal momenta, eventually restoring the longitudinal component with radiofrequency cavities. The result is a reduction of the transverse emittance which can be traduced as an increase of the phase space density. In the present talk I will introduce MICE, describe the recent results and outline possible future scenarios.

[recording]

: Kristin Lohwasser (Sheffield)

Photon collisions at the LHC: Probing the electroweak sector

The observation of WW production in photon collisions, yy->WW, represents a mile stone in the quest to fully characterize the electroweak sector of the SM. The talk will discuss the details of this challenging measurement: Origin of photons at the LHC, treatment of pile-up and the modelling of the signal as well as that of the underlying event for background processes. An outlook on how this will play a role for future tests of the Standard Model and in searches of new physics at the TeV scale is given.

[recording]

: John Nugent (Glasgow)

WAGASCI: A New Near Detector at T2K

WAGASCI is a newly installed detector at the J-PARC facility and part of the T2K experiment. Located at the end of the neutrino beam line it provides measurements of the neutrino flux before oscillation. Its design is fundamentally different from the existing near detectors and offers the first opportunity to measure the ratio of neutrino cross-sections on water and hydrocarbon to within a total uncertainty of 3%. This will allow neutrino nuclear scattering to be probed to a never before achievable extent. Developing our understanding of neutrino nuclear interactions is critical to the future of T2K and the long baseline neutrino program in general. Only through understanding these interactions can T2K reached the desired sensitivity to CP violation in leptons. A measurement of CP violation in neutrino oscillation would constitute one of the most significant breakthroughs in the field of particle physics for decades. In this seminar the WAGASCI detector will be introduced and the status after its first commissioning and physics runs reported.

[recording]

: Jost Migenda (Kings College London)

The Hyper-Kamiokande Experiment

Hyper-Kamiokande is a next generation neutrino and nucleon decay experiment that is expected to start taking data in 2027. In this talk, I will introduce the experiment and current construction progress. I will then give an overview over its broad physics programme, with a special focus on neutrino astronomy.

[recording]

: Ben Kilminster (UZH)

Probing 10 orders of magnitude of dark matter mass using CCDs: New results from DAMIC@SNOLAB and prospects for DAMIC-M

"The DAMIC (Dark Matter in CCDs) experiment uses CCD detectors to search for the direct interaction of galactic dark matter. Scientific CCD detectors provide an unprecedented low energy threshold and spatial resolution to probe for light dark matter. Given the current lack of evidence for a WIMP of mass around the weak scale, DAMIC focuses its search on lighter WIMPs, as well as the interaction of hidden-sector photons that could mediate the interaction of DM or even comprise DM. The current experiment, DAMIC@SNOLAB pioneered the search for hidden-photon interactions of DM and set world-leading constraints for low-mass WIMPs with a silicon-based target. The next experiment, DAMIC-M at LSM (Laboratoire Souterrain de Modane in France) will be sensitive to never-before probed potential DM models, covering a broad range of models spanning from eV to 10 TeV. In this talk, exciting new results from DAMIC@SNOLAB and prospects from DAMIC-M will be presented."

: Artur Sztuc (UCL)

Recent neutrino oscillation results from the T2K experiment

T2K is a long baseline neutrino experiment using a beam of mostly muon neutrinos from the Japan Particle Accelerator Research Centre in Japan, and measuring their oscillated state 295 km away in the Super-Kamiokande detector.  Measuring the change in the neutrino flavour at Super-Kamiokande constrains the neutrino oscillation parameters of the PMNS matrix, specifically Δm232, sin2 θ23 and the CP-violating phase ΔCP. The 2019 results from T2K have shown a strong constraint on ΔCP, with large regions of ΔCP excluded at 3σ CL. This talk will describe results from T2K with the data collected until early 2020, and the future prospects for the experiment.

[slides]

: Martin Slezak (Max Planck Inst.)

First neutrino mass results from the KATRIN experiment

Knowledge of the absolute neutrino mass scale is of particular importance to particle physics, astrophysics and cosmology. The Karlsruhe Tritium Neutrino (KATRIN) experiment aims to search for the effective electron antineutrino mass with an unprecedented sensitivity of 200 meV from the shape of tritium beta-decay spectrum near its kinematical endpoint. In 2019 KATRIN performed the first measurement yielding a new upper limit of 1.1 eV (90 % C.L.) for the neutrino mass using beta-decay. In this talk, I will give an overview of the KATRIN experiment and discuss the first neutrino mass campaign in detail. I will also briefly mention perspectives for the next measurement which took place in 2020 and is currently under analysis.

[recording]