Research Themes

Searching for BSM using dataset topology. This project is an entirely new approach to LHC new-physics searches, exploiting for the first time the relationships between collider events, to discriminate between SM and beyond Standard Model (BSM) physics. A graph network is built in which individual events appear as nodes, with edges between events reflecting their similarity in kinematic space. Properties of the graph nodes describe the dataset topology, providing discrimination between BSM and SM processes based more on rarity and variability in the signal than a specific models kinematics. Considering several definitions of similarity provides a plethora of event variables that can be used in addition to existing kinematic information to achieve good sensitivity in a prototype electroweak supersymmetry search. Possible new physics searches benefitting from this approach, and the potential to attain model-independent sensitivity to new physics are currently being explored.
Part of a joint grant with Adelaide "Optimising the search for the next discovery in particle physics"

Data-driven searches for unexpected asymmetries The first paper in this theme searched for violation of lepton charge-flavour symmetries in emu events a unique data-data comparison with sensitivity to many BSM models, such as R-Parity violating supersymmetry (RPV-SUSY) and scalar leptoquarks. Future projects could further probe the emu ratio, or extend it to taus.

Searching for electroweak supersymmetry. This project was 2/3 of my PhD, where I was the main analyser in searches for electroweak supersymmetry (SUSY) in 2 lepton final states, primarily targetting chargino pair production decaying via W bosons, but also searching for direct slepton production and chargino production decaying via sleptons, placing world-leading limits at the time using the full ATLAS Run-2 dataset. I am also involved in future developments aiming to close the gap at low mass-splittings, having performed many initial studies on utilising machine learning (BDTs) for SUSY/SM classification, and using flavour symmetry to improve the data-driven standard model background estimate. I plan to expand this theme into searches for the tau's superpartner: the stau.

Detecting undetectable particles: missing transverse momentum (MET) I am currently the co-leader of the 'missing transverse momentum and pileup jet tagging' group at ATLAS. We work on developing ATLAS's ability to infer the presence of otherwise undetectable particles, like neutrinos and dark matter, which is a crucial part of many searches and measurements at ATLAS. During my PhD I worked on calcuting uncertaintes on the missing transverse momentum reconstruction, which are used ATLAS-wide. Current work includes Machine learning approaches to improve MET reconstruction and define new MET-based variables to better discriminate between BSM and SM physics in searches.

"Global fits and future collider studies with GAMBIT I am a new member of the GAMBIT community. My latest research theme is to contribute to global fits of existing results in full BSM models, in order to establish which models of BSM parameter space are most favoured and should be targetted in future searches. I aim to interpret these also in the context of future collider sensitivity.

Publications

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Search for direct pair production of sleptons and charginos decaying to two leptons and neutralinos with mass splittings near the W boson mass in √s=13 TeV pp collisions with the ATLAS detector
ATLAS Collaboration.CONF Note on CDS
I performed initial studies on using Machine Learning to discriminate between the chargino signal and background, and into the flavour-subtraction background estimate used for the slepton search.
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A search for an unexpected asymmetry in the production of e+mu- and e-mu+ pairs in proton-proton collisions recorded by the ATLAS detector at √s=13 TeV
ATLAS Collaboration.
[arXiv:2112.08090], submitted to Phys. Letters B
CONF Note on CDS
I led this analysis searching for e+mu- production exceeding that of e-mu+, which would defy the LHC charge-flavour conspiracy to provide evidence for new physics. The analysis is the first of its kind, and pleasingly data-driven. We also placed new limits on RPV SUSY and scalar leptoquark models in single-production modes.
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METNet: A combined pTmiss working point using a neural network with the ATLAS detector
ATLAS Collaboration.
PUB Note on CDS
I helped supervise PhD student Ben Hodkinson on the project, and had the idea to extend the work to develop a Machine Learned MET Significance variable.
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Does SUSY have Friends? A new approach for LHC event analysis.
Anna Mullin, Stuart Nicholls, Holly Pacey, Michael Parker, Martin White, and Sarah Williams.
JHEP 02 (2021) 160 [arXiv:1912.10625]
I designed the prototype electroweak-SUSY analysis.
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Search for electroweak production of charginos and sleptons decaying into final states with two leptons and missing transverse momentum in sqrt(s)=13 TeV pp collisions using the ATLAS detector.
ATLAS Collaboration
Eur. Phys. J. C. 80 (2020) 123 [arXiv:1908.08215]
I designed the search and performed the statistical analysis.
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Search for direct chargino pair production with W-boson mediated decays in events with two leptons and missing transverse momentum at sqrt(s)=13 TeV with the ATLAS detector.
ATLAS Collaboration (I designed the search and performed the statistical analysis).
ATLAS-CONF-2018-042
July 2018.
I designed the search and performed the statistical analysis.
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Search for electroweak production of supersymmetric particles in final states with two or three leptons at sqrt(s)=13 TeV with the ATLAS detector.
ATLAS Collaboration.
Eur. Phys. J. C. 78 (2018) 995,475 [arXiv:1803.12762]
I designed the data-driven SM background estimate in the 2 lepton 0 jet channel.

Talks

Conference Talks

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PANIC 2021, Virtual (Lisbon, Portugal) 05/09/21.

EW SUSY Production at the LHC


Proceedings

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SUSY 2021, Virtual (Beijing, China) 23/08/21.

Missing transverse momentum reconstruction at ATLAS


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QCD@LHC 2019, Buffalo, USA 15/07/19.

QCD and the search for exotic physics


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IoP HEPP/APP 2019, London, UK 09/04/19.

Searching for new physics with emu asymmetry at the ATLAS detector


Seminars

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Cambridge HEP Seminar Series, Cambridge UK 09/03/21.

Does SUSY have friends? A new approach for LHC analysis


ATLAS Collaboration major internal talks

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ATLAS UK annual meeting 2022, Online. 01/22.

Chairing session on ATLAS reconstruction performance


ATLAS Collaboration Week October 2021, Online. 10/21.

Overview of work in the JetEtMiss group


ATLAS Exotics Workshop 2021, Online. 09/21.

`New and uncovered analyses in the Lepton+X subgroup'


ATLAS Hadronic Calibration Workshop 2020, Online. 09/20.

Chaired session on MET, talk on future MET systematics strategy.


ATLAS Physics and Performance Week 12/2019, Online. 10/12/19.

Overview of ongoing work in the MET and pileup jet tagging subgroup.


ATLAS Hadronic Calibration Workshop 2019, Tucson USA. 14/10/19.

Chaired session on MET, talk on MET group activities.


ATLAS UK joint SUSY/Exotics Meeting 2019, Cambridge UK. 11/04/19.

"Searching for new physics with emu asymmetry at the ATLAS detector"


ATLAS UK Annual Meeting 2019, London UK. 04/01/19.

"Electroweak SUSY Searches"


ATLAS Physics and Performance Week 09/2018, Online. 20/09/18.

Overview of ongoing work in the Exotics lepton+X subgroup.


ATLAS Hadronic Calibration Workshop 2018, Heidelberg Germany. 12/09/18.

"Introduction to MET and pileup jet tagging."


ATLAS Supersymmetry Workshop 2018, Stockholm Sweden. 23/05/18.

"Overview of the current Electroweak SUSY search programme"


Posters

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Evolution of Regional, Age and Gender Demographics in the ATLAS Collaboration
LCHP 2022 Conference
17/05/22
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Hunting Electroweak Supersymmetry with two leptons and missing transverse momentum at 13 TeV with the ATLAS detector
IoP HEPP/APP 2019 Conference
08/04/19
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Hunting Electroweak Supersymmetry with two leptons and missing transverse momentum at 13 TeV with the ATLAS detector
137th LHCC Meeting
27/02/19
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Searching for New Physics in Lepton Charge Flavour Asymmetry
ATLAS Overview Week Tokyo
16/06/18
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Estimating the flavour symmetric background in a search for Compressed Electroweak Supersymmetry
STFC High Energy Physics Summer School
04/09/17