Bob Kowalewski

I conduct research in experimental particle physics. I am currently involved with two principle research efforts:

• Studies of weak interactions and CP violation (the breakdown of the symmetry between matter and anti-matter) with the BELLE-II detector at the KEK laboratory in Japan
• Searches for new phenomena at the high energy frontier with the ATLAS detector at the European Centre for Particle Physics (CERN)

I welcome new students on Belle II

Belle II is an experiment in Japan that has sensitivity to new physics in the decays of heavy quarks and leptons.  The Belle II detector and SuperKEKB electron-positron collider began collecting physics data in 2019 and have collected a sample nearly as large as the previous generation of experiments.  The ultimate dataset will be ~50 times bigger and will allow sensitive precision tests that complement the high energy frontier experiments in our search for physics beyond the standard model.  My research in Belle II centres on semileptonic decays of B mesons, including the determination of the coupling strengths (|Vub| and |Vcb|) between the b quark and the u and c quarks (see this review article) and searches for non-standard-model phenomena such as lepton flavour universality violation.  Belle II builds on the results of the Belle and BaBar experiments, which were cited in the 2008 Nobel Prize in Physics for confirming the predictions of Kobayashi and Maskawa about the violation of CP symmetry (which is a necessary ingredient in understanding the matter-antimatter asymmetry in the universe).

ATLAS collected the 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. My research group on ATLAS is focused on data analysis and on software development and operations for the High Level Trigger and the reconstruction of missing transverse momentum (MET).  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.  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.  My group has responsibility for HLT signatures based on MET which are essential for searches for new, non-interacting particles (e.g. Dark Matter candidates).  We also work to improve the reconstruction of MET for offline data analysis.  Members of my group have worked on studies of the Higgs Boson in the gamma-gamma decay channel, on searches for dark matter candidates using events with jets or vector bosons recoiling against MET and on measuring top-quark production cross-sections in the WbWb final state.

Research interests

• Quark flavor physics
• Electroweak physics
• Dark matter particle searches
• Trigger development
• Machine learning