07 Dec 2021



Exotic particle searches with ATLAS Run 3 data and preparing Tracking software for High Luminosity LHC


Co-supervisors: PPD - T. Adye, Royal Holloway, University of London - T. Berry

Low-mass dimuon or dielectron resonance searches are challenging due to large backgrounds below the Z. Presently such searches are limited by the capability to store all the collisions containing low momentum leptons on disk for future physics analysis. 

In Run 3 we plan to carry out such an analysis in the online selection of the collision events in a so-called Trigger Level Analysis (TLA) for muons (and electrons).  ATLAS successfully implemented a TLA only for dijets in Run 2 and we intend to build on this success. TL analyses enable data to be stored with smaller event sizes as only selected data is written out and therefore we can afford to record these collisions which cannot be achieved with our  traditional triggers. This is an exciting prospect and opens up the possibility of probing for new physics signals in new regions. In our case we are looking for deviations from the Standard Model at low invariant mass due to exotic physics, such as dark photons.

After Run 3, the LHC will be upgraded to the High-Luminosity LHC. This will require a major upgrade of the ATLAS detector, including a new all-silicon inner tracking detector (ITk). As part of the ACTS project, the ATLAS track reconstruction software is being rewritten with improved algorithms and modern software engineering practices to take full advantage of the new detector and emerging computing architectures.


On the RHUL side, this project will be supervised by Dr Tracey Berry, an expert (20 years experience) in dilepton searches, supported by RHUL trigger software experts. At RAL, the group has a wealth of expertise in the ATLAS tracking software in the High-Level Trigger and offline systems. The studentship includes developing new track reconstruction software for the ITk, as well as performing an analysis for a low mass resonance search using the new Run 3 data. This is the ideal time and place to perform this research. The Large Hadron Collider will restart in Spring 2022 enabling the student to exploit the new higher energy dataset (@13.6 TeV). At the same time, construction and software development for the Phase II upgrade is ramping up. The research would be published and presented internationally at workshops and conferences.

Contact: Adye, Tim (STFC,RAL,PPD)