James Frost

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James Frost

Royal Society URF

I am a particle physicist, Royal Society University Research Fellow and member of the ATLAS Collaboration working in the Oxford Particle Physics subdepartment.

My research focuses on searches for ground-breaking physics, the theoretical modelling and simulation of these phenomena, and the operation of the ATLAS experiment.

Research

My group and I look for evidence of new particles and phenomena beyond the well-understood Standard Model of Particle Physics.

I have advanced our modelling and simulation of collider black holes through the development of the CHARYBDIS simulation program, including angular momentum and spin for the first time, and superior production and decay models. I led several searches for such exotic states in ATLAS using data from LHC Run-1.

I was editor of the first ATLAS search paper of Run 2, looking for new phenomena in high-energy LHC events with two jets - particle showers initiated by high-momentum hadrons in the detector. This analysis set very strong limits on dark matter mediator particles. By using new and innovative analysis strategies looking for additional radiation or trigger-level analysis, we extended these searches - providing sensitivities to much lower mass particles.

Current Research: My research focuses on channels using the discovered Higgs boson as a tool to search for new particles and evidence of dark matter.

I search for the mono-Higgs production signature: pair production of dark matter particles, produced in association with a single Higgs boson. Due to the unique nature of the Higgs, interactions between dark matter and it may be stronger and more important than those with other SM particles.

In many of these predictions, there is an additional piece of the puzzle - a heavier Higgs boson which mediates the dark matter interactions and which decays to two of the known Higgs bosons.
I search for this di-Higgs signature in its four b-quark final state - the most common decay, but one where high backgrounds must be well understood. Improving this sensitivity of this signature is critical, with the large volumes of data from the LHC's High Luminosity run, we will be able to measure to the Higgs self-coupling - one of the last unmeasured parameters of the Standard Model.

In many models, dark matter mediators are expected to have enhanced rates to heavy quarks. By searching for decays to bb with initial state radiation jet allowing us to select these events, we can search for these dark matter mediators at lower masses. This channel is also sensitive to boosted bb decays of the Higgs boson, allowing a measurement of the Higgs+jet process at high Higgs momentum.

Complementing phyiscs analysis, currently I work on means of calibrating topologies with two close-by b-quark jets. I have also worked on improving the ATLAS jet software.

I have held a range of operational roles, including responsibilities for ATLAS prompt reconstruction and Data Quality. In 2016, I was elected to be Data Preparation Coordinator, one of the four ATLAS activity area coordinators (the others being physics, trigger and computing), sitting on the Executive board - the main body for the direction of ATLAS. In this critical position from 2016-2018, I led a diverse team of physics, operational and computing experts to process, assess and understand all data recorded.