ProfessorKevin Varvell

Project Opportunities

Title: Particle Physics with the ATLAS Detector at CERN's Large Hadron Collider

Summary of opportunity:

This project provides the opportunity (both PhD and MPhil) to join the global effort to search for physics beyond the Standard Model of Particle Physics using data from the ATLAS Experiment at CERN’s Large Hadron Collider.

Opportunity synopsis:

The ATLAS experiment at the Large Hadron Collider (LHC) at CERN has now been collecting data since the start of 2010, with an enormous number of proton-proton collisions having been collected to date at collision energies of 7 TeV, 8 TeV, 13 TeV and 13.6 TeV. Whilst only a select fraction of these collisions are recorded for further study, the resulting data set is still huge. The search for the Higgs boson was successful, with its discovery announced in 2012. The focus has now become precision studies of the properties of the Higgs, precision studies of the Standard Model of Particle Physics (SM) at unprecedented energies, and searches for ”physics Beyond the Standard Model'' (BSM). The School of Physics has interests in several aspects of the ATLAS programme, notably: 

• Studying the decays of neutral Higgs bosons, to better understand the properties of the Higgs. The new boson observed at the LHC, with a mass of around 125 GeV, could simply be the long-sought-after Standard Model Higgs boson or something more exotic. A lot of effort in ATLAS is now going into prising out its properties.
• Understanding the production of multiple top quarks at ATLAS. Measurement of mutli-top production forms a good test of the Standard Model as well as an important Standard-Model background to new physics processes. While in previous colliders the production of top-antitop pairs was a rare occurrence, this is not the case at the LHC. It is even now possible to see 4-top production at the LHC experiments. Top physics is interesting in its own right since, due to it being extremely heavy, the top quark does not form mesons before decaying, which allows the study of instrinsic quark properties such as the spin using the final state particles. 
• Preparing for future upgrades of the ATLAS detector. The third major running period of the LHC has recently come to an end. The ATLAS detector is undergoing an upgrade to allow it to operate at the higher beam intensity environment which will be present when the LHC itself is upgraded over the next several years to the High-Luminosity LHC (HL-LHC).

Specific projects could be tailored to suit the particular interests of students.

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Project Opportunities

Title: Particle Physics with the Belle II detector at the SuperKEKB electron-positron collider

Summary of opportunity:

This project provides the opportunity (both PhD and MPhil) to join the global effort to search for physics beyond the Standard Model of Particle Physics using data from the Belle II Experiment at KEK’s SuperKEKB electron-positron collider.

Opportunity synopsis:

The Belle II experiment at the SuperKEKB electron-positron collider in Japan has now been data-taking for several years. It primarily studies rare decays of particles known as B mesons, in order to make precision tests of the Standard Model (SM) of Particle Physics and to search for physics “beyond the Standard Model” (BSM), including for dark matter. It can also search for new exotic states containing quarks and gluons. The University of Sydney is a member of the Belle II collaboration, and areas within which projects could be offered include: 

• searches for purely leptonic decays of B mesons, such as a charged B meson decaying to an electron, muon or tau lepton and associated neutrino. The first two of these decays are extremely rare and have not been observed to date, and all three decays are particularly sensitive to BSM physics.  
• studies of so-called semileptonic decays of B mesons, where in addition to an electron, muon or tau lepton and associated neutrino, a meson is also produced. Like purely leptonic decays, semileptonic decays are sensitive to BSM physics, and also allow for the determination of fundamental parameters of the Standard Model of Particle Physics (SM).
• studies of other rare processes using Belle II data.
• preparations for future planned upgrades of the Belle II detector to operate at higher beam intensities from the SuperKEKB collider, for example in the area of triggering of the detector.

Specific projects could be tailored to suit the particular interests of students.