Prof. Robert KOWALEWSKI
Transforming Africa with Experimental Particle Physics
Prof. Kowalewski conducts research in experimental particle physics. He is involved with two principle areas:
- Searches for new phenomena at the high energy frontier with the ATLAS detector at the European Centre for Particle Physics (CERN);
- Studies of weak interactions and CP violation (the breakdown of the symmetry between matter and anti-matter) with the BaBar detector at the SLAC National Accelerator Laboratory and the BELLE-II detector (under construction) at the KEK laboratory in Japan.
ATLAS began collecting first physics data in 2009, established the existence of a Higgs boson in 2012 and is exploring new territory with higher energy and higher intensity beams from the LHC. Kowalewski’s group on ATLAS focuses on data analysis and on software development and operations for the High Level Trigger (HLT). The HLT is a large parallel computing facility that makes the final decision on whether or not to write each collected event to permanent storage, and must reduce the input event rate by a factor of ~200. Continued increases in LHC luminosity require corresponding improvements to the HLT in order to preserve sensitivity to important physics signatures in the presence of higher backgrounds. His group has responsibility for HLT signatures based on missing transverse momentum, which are essential for searches for new, non-interacting particles (e.g. Dark Matter candidates). On the data analysis front, the group has worked on studies of the Higgs Boson in the gamma-gamma decay channel and on searches for dark matter candidates using events with a jet or Z boson recoiling against missing transverse momentum. His students have used machine learning approaches to improve performance on classification problems of interest.
BaBar began operation 1999 and finished collecting data in 2008, but continues to publish new results. Kowalewski’s research in BaBar centres on semileptonic decays of B mesons, and in particular on the determination of the coupling strengths (|Vub| and |Vcb|) between the b quark and the u and c quarks (see this review article). These parameters play a crucial role in testing the adequacy of the Standard Model description of CP violation, and in quantitative tests of flavour physics. The 2008 Nobel Prize in Physics cites the work of the BaBar experiment in confirming the predictions of Kobayashi and Maskawa. Belle II is a next-generation experiment in Japan that will have greater sensitivity to new physics in the decays of heavy quarks and leptons. The Belle II detector and SuperKEKB accelerator are being commissioned in 2017, and the first full physics run is scheduled to start in 2018.
Prof. Kowalewski has taught at AIMS South Africa.
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