Pandemic Particle Physics: A Sabbatical Saga by TODD PEDLAR, Professor of Physics
The research I do with my students and my colleagues near and far is done as part of the Belle and Belle II Collaborations—1000-strong collaborations which have operated experiments at KEK, the national high energy physics laboratory of Japan, since 1999. I have collaborated on Belle and Belle II since 2010, when Belle II was little more than a twinkle in the collective eye of
the Belle Collaboration, which had just completed data taking on the original Belle Experiment. Since then, Luther has been an institutional member of these collaborations, one of the 126 participating institutions from 26 countries around the world. The physical processes that we study concern the decays of objects known as baryons and mesons (which are composed of quarks and antiquarks at the fundamental level). Baryons, like the proton, are composed of three quarks, while mesons, the lightest of which is known as the pion (𝜋), consist of a quark-antiquark pair. Most of the systems we study involve one or more heavy quarks (strange, charm, and/or bottom). By measuring the masses and studying the decay processes undergone by these heavy quark systems, we are able to gain insight into the force that binds these systems, the strong nuclear interaction. In order to study the decays of heavy mesons and baryons most effectively,
The Belle II detector on the Super-KEKB beamline at KEK in Tsukuba, Japan. Copyright KEK
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Agora/Fall 2021
PHOTOS COURTESY OF THE AUTHOR
T
he final week of spring semester 2019 was at its end. As the summer of 2019 was around the corner, the thought rang through my mind: “The next time I’ll be in the classroom for a class meeting is now 15 months away!” The blessing of a year-long sabbatical was upon me, through the generous support of the National Science Foundation, which made a year-long sabbatical possible. The anticipation of a full year of completely diving into my research and being able to devote myself fully to the research that students whom I would have over the coming two summers and the intervening academic year was palpable.
Todd Pedlar one must identify all the decay products of a given decay process and measure their energies and momenta. In many cases, a given heavy meson decays by way of a cascade of a few steps until finally what remains are those particles referred to as “final state particles,” which are either stable or long-lived enough to exit the detector before undergoing further decays. The work that we do specifically at Luther involves both studying the various decays of heavy mesons, and, in service of Belle II, developing software for final state particle identification. In the spring of 2019, the Belle II Experiment had begun in earnest, at long last, after many years of preparation, construction, and testing of various component parts of the detector and accelerator systems. As my sabbatical started, in June of 2019, we were beginning to work out the kinks of an essentially brand-new detector system,
