4th Year Projects in 2012

ATLAS Experiment: Di-electron decays of quarkonium states at ATLAS

 Supervisors: Dr Bruce Yabsley and Dr Anthony Waugh Contact: Dr Bruce Yabsley Room: 366 Email: bruce.yabsley AT sydney.edu.au Phone: 9351 5970

The quarkonium mesons - the various positronium-like ccbar and bbbar bound states - play an important role in particle physics, and they are copiously produced at the LHC. With their clean experimental signatures, they provide tools for the study of other particles; they are also objects of study in their own right, with a recent ATLAS paper (arXiv:1112.5154 [hep-ex], accepted for publication in PRL) announcing the observation of a new bbbar state. With the increasingly large dataset available at ATLAS, there is a growing interest in "associated production" of quarkonia: production of a quarkonium state together with either another quarkonium, or a system with open heavy flavour (charm- or b-quark jets). The rate and characteristics of such events act as probes of the fundamental processes at work when heavy quarks are produced.

In this project, you will develop an analysis of associated production of Υ mesons. This will add to our existing work on searches for quarkonia (and quarkonium-like mesons) in the π+ π-, J/ψ and π-, Υ final states, and the reconstruction of J/ψ and Υ \to e+ e-.

Belle Experiment: Fully reconstructed charmed semileptonic decays of B mesons at Belle

 Supervisors: Dr Alexei Sibidanov and A/Prof. Kevin Varvell Contact: Dr Alexei Sibidanov Room: 364 Email: alexei.sibidanov AT sydney.edu.au Phone: 9351 2712

Studying semileptonic decays of B mesons gives us a way to determine parameters of the Standard Model of Particle Physics, and ultimately to search for hints of physics beyond the Standard Model. We study these decays using the large dataset of the Belle experiment at KEK in Japan, which produced around 770 million pairs of B mesons during the last decade. A new experiment, Belle II, is being developed which will eventually provide over 50 times this number of decays.

Belle has in recent times developed an improved full reconstruction technique which is a very clean way of isolating particular B meson decays of interest. This will become a crucial tool when Belle II comes online, and its strengths and weaknesses need to be understood as best they can. Right now there are a number of measurements which would be ideal for doing this, including studying the decays of B mesons to charmed mesons, D and D*, a lepton and a neutrino. We have some experience with this already, but would like to extend our studies, in particular by including other decay modes of the D meson, such as those to a neutral kaon, KS0.

This research project which will give a good taste of the nature of experimental particle physics research and in particular the data analysis methods which are typically employed.