Particle Physics Experiment

We expect to offer an STFC-funded studentship working on ATLAS, starting in Sept/Oct 2025.

The Large Hadron Collider (LHC) at CERN is probing the structure of matter at the highest energies achieved in a collider.  By making precision measurements in Higgs, top-quark, and electroweak physics we can probe the structure of the Standard Model and looking for deviations that could indicate new physics. 

Following the discovery of a Higgs-like particle at the LHC in 2012, many measurements remain to be made to verify whether it is a Standard-Model Higgs boson, or something more exotic.  In the ATLAS collaboration, the Glasgow group's main efforts are in the channels where a Higgs boson decays to b-quarks.  The LHC is a top-quark factory, and the ATLAS datasets allow unprecedented measurements of this, the heaviest of the known elementary particles.

We also study the behaviour of the strong nuclear force, Quantum Chromodynamics, which is a key factor in all LHC analyses and presents many theoretical difficulties that can only be resolved by confronting predictions with increasingly challenging experimental measurements. Our QCD analysis efforts are centred on understanding how heavy c and b quarks are produced, and the structure of QCD particle jets: these aspects of QCD are central to our programme of Higgs and top-quark measurements.

The successful candidate will undertake exciting research within a strong Glasgow ATLAS group.  They will be expected to travel for short trips to CERN, Geneva and will have the opportunity to spend an extended period at CERN.

Projects for 2025 are listed below:

ATLAS Project 1:  Double-Higgs production

Supervisor: Prof Aidan Robson

The extent to which Higgs bosons interact with themselves - the Higgs self-coupling - is a critical parameter of the standard model that has deep connections to phase transitions in the early universe.  So far it is very weakly constrained.  The first step towards determining the Higgs self-coupling will be the observation of pairs of Higgs bosons being produced in a single interaction at the LHC.  This project will exploit the entire Run-3 dataset to attempt to measure double-Higgs production and constrain the Higgs self-coupling, as well as searching directly for new particles that decay to pairs of Higgs bosons.  We will also prepare to exploit the new detectors and experimental conditions of the High-Luminosity LHC.

We may also be able to offer:

ATLAS Project 2: Searching for new physics in the Higgs-top-quark coupling

Supervisor: Prof Mark Owen

In the standard model, the mass of the fermions is generated by interactions of the fermions with the Higgs field. This means the huge mass of the top quark (the heaviest fundamental particle observed to date) is understood in the standard model as originating from a very strong coupling between the Higgs boson and the top quark. We can measure this coupling by measuring the simultaneous production of a Higgs boson and two top quarks (ttH). If we were to see differences to the standard model prediction, then this could be a sign of new physics beyond the standard model. In this project we’ll analyse the LHC Run-3 data to measure the ttH process, targeting high momentum Higgs bosons where deviations from the standard model are most likely to occur.

We expect to offer an STFC-funded studentship working on LHCb, starting in Sept/Oct 2025.

Potential projects for 2025 are listed below:

LHCb Project 1: Exotic hadrons

Supervisor: Dr Mark Whitehead

We are currently in a golden age for spectroscopy measurements, led by the Large Hadron Collider beauty (LHCb) experiment at CERN. The LHCb experiment has discovered 64 hadronic particles, with 23 so-called exotic candidates. These exotic hadrons are made from combinations of 4, 5, or perhaps even 6 quarks. Studying excited hadrons provides a test for our understanding of the strong interaction, with such particles being predicted by techniques such as lattice QCD.  The perfect laboratory to explore these phenomena are decays of beauty hadrons (containing a b-quark) to final states including charm hadrons (containing a c-quark). New data samples from LHC Run 3 will provide more data and opportunities than ever before.

Accurate simulations of particle physics processes are crucial to model the production of particles at the LHC, and describe the detectors and the interactions between the particles and the material.  Alongside the data analysis part of this project, development work on the simulations will support physics analyses and the design and optimisation of new detectors for LHCb.

PhD students in this area work within the Glasgow LHCb group of seven research staff and four PhD students.  Activities include the analysis of data, and running and operating the experiment.  Students are expected to travel to CERN in Geneva regularly, and to spend a period of around one year based at CERN.

We expect to offer an STFC-funded studentship working on T2K/Hyper-K, starting in Sept/Oct 2025.

The Glasgow group is involved in the Japan-based Kamioka neutrino program, working primarily on the 295km-baseline T2K experiment; detection of astrophysical and reactor neutrinos with Super-K; and on the design and construction of the next-generation Hyper-K experiment.  
The main physics goal of the program is to establish whether CP symmetry is broken by neutrino oscillations.  CP symmetry implies that the laws of physics treat matter and anti-matter the same way, with the only known exception being the Kobayashi–Maskawa (KM) mechanism.  This is well-established in neutral mesons, but is thought to be insufficient to explain the dominance of matter in the observable universe.  Neutrino oscillations are the only other system known where the KM mechanism could occur, and the T2K experiment has recently provided tantalising hints that CP symmetry might be broken here as well.

Projects for 2025:

T2K / Hyper-K Project:  Novel analyses of neutrino oscillations

Supervisor: Dr Phill Litchfield

The group collaborates closely with a handful of other institutes at the cutting edge of neutrino oscillation measurements, and we have a particular focus on novel analyses and combinations with other experiments.  We are pioneering new methods to reduce the computational difficulty of CP-violation searches and build confidence in a positive signal by distinguishing between a real observation and artefacts caused by modelling uncertainties. This project will take the current proof-of-principle analyses and evolve them into a full search for CP violation with T2K data.  In addition, the PhD lines up well with the construction of the 71m tall Hyper-K detector, and there is the opportunity to get some hands-on experience with photosensors and read-out electronics before the detector is filled with water, which will make it inaccessible for the next 20 years.

The successful candidate will work with the Glasgow group and collaborators in the UK and abroad.  They will be expected to travel for short trips to Japan and CERN, and have the opportunity to spend an extended period of up to a year working in Japan with other UK graduate students and international researchers.

In addition, the group is leading developments of a new beam target for Hyper-K and the detection of low-energy neutrinos in Super-K and Hyper-K, for example to detect stars in the last stages before a supernova.  We would be glad to consider candidates for scholarship funding in these topics or oscillation research.

We do not expect to offer an STFC-funded studentship in detector development for 2025; however, we are glad to consider candidates for scholarship funding.

The Glasgow Experimental particle physics group has a long-standing expertise in the development and deployment of advanced detector systems for particle physics and for applications outside of particle physics.

The group has a focus on the development of silicon-based detectors and data transfer off module. Presently we are focused on the development of the upgraded ATLAS and LHCb silicon vertex and tracking sub-detectors. For the ATLAS project we have developed the strip detector module and the pixel detector module for the inner tracking system, the ITk. For LHCb, we developed the opto-electrical data transfer links for the present vertex upgrade and are now working on fast timing pixel detectors for the VELO (vertex detector) and on monolithic CMOS sensors for the Mighty Tracker.

For application outside of the particle physics we are developing small pitch pixel sensors with internal gain to be coupled to the TimePix family of pixel chips. Working with many industrial partners we are developing devices and systems for X-ray and electron detection for a range of applications, including for synchrotrons and electron microscopy.

We have a wide range of equipment to support technology research and development, including our own flip-chip bonder for pixel muddle assembly, wire-bonders, probe stations, and a comprehensive range of device characterisation and metrology equipment.

PhD opportunities exist for the development of sensors including monolithic CMOS and fast timing sensors, module assembly techniques, DAQ, data-transfer techniques for the next generation of particle physics experiments and for applications outwith particle physics. Excellent opportunities exist for training, working overseas and placements at industrial partners.

We do not expect to offer an STFC-funded studentship in this area starting in Sept/Oct 2025, but would be glad to consider candidates for scholarship funding.

The Glasgow group has been a central part of the analysis of the pre-2018 data, working on both the normalisation channel and the upstream backgrounds in the signal channel.  The LHC "Long Shutdown 3" has provided a window of opportunity to develop more modern analysis techniques using Machine Learning to improve upon previous cut-based analysis for the data taken from 2021 onwards.