8/1/2005
Young-Kee Kim: Research
I do research (1) on experimental particle physics using colliders (LHC now; Tevatron and TRISTAN in the past) to understand how the universe works at the most fundamental level by discovering and understanding the fundamental constituents (elementary particles) and the forces acting among them and (2) on accelerator physics to design and build much more powerful (much higher energy and/or much higher intensity) accelerators for future particle physics and other sciences. my accelerator research group
Current Activities:
ATLAS Experiment at LHC proton-proton collider
2012 was was a watershed for particle physics. The decadeslong
quest to discover the Higgs boson, the last puzzle piece in the current theory of particle physics
(the standard model), is essentially complete. But this theory does not explain some fundamental aspects of
our Universe. From the neutrino's very small mass to our matter-dominant universe, dark matter and dark energy,
we know there is more going on. My research addresses some of these unanswered questions by searching for
new physics at the Large Hadron proton-proton Collider (LHC) at CERN, currently the highest-energy accelerator in the world.
After a two-year upgrade, LHC resumed its operation at 13 TeV late 2015
-- roughly twice that at which the Higgs was discovered.
Any new particles or new physics found at LHC will ervolutionalize our view of physics.
Using the ATLAS detector at LHC, my group focuses on (i) a deeper understanding of the nature of the Higgs (Higgs decays and Higgs potential), (ii) searches for new physics using the Higgs as a new tool (e.g. decay of Higgs into dark matter particles), and (iii) searches for a new messenger particle that couples to both dark matter an quarks. Achieving these goals requires significant improvements of detectors and triggers. My group has been working on the new track-base trigger (EF Tracking) that has more capability and flexibility than the current trigger system.
Accelerator Physics In addition, my group is exploiting novel concepts in accelerator science and technology, studying limitations affecting the acceleration and intensity of particle beams at a fundamental level, and developing new approaches to overcome these limitation. We use accelerator research facilities located at national laboratories such as Fermilab, Argonne and SLAC and collaborate with accelerator scientists in these national laboratries. Some of them co-advise my students with me.
Past Activities:
CDF Experiment at Tevatron proton-antiproton collider (1990 - 2013)
Until 2009, the Tevatron proton-antiproton collider was the world's highest energy accelerator
and the top quark, the most massive
elementary particle, was discovered in 1995 by the CDF and DZero experiments at the Tevatron.
Using the CDF detector at the Tevatron, my group measured the masses of the W boson and
the top quark very precisely (numerous measurements were made using different decade modes,
different datasets and different analysis techniques). These measurements predicted the mass
of the Higgs boson to be less than 145 GeV. The mass of the Higgs boson (discovered in 2012)
turned out to be 125 GeV!
My group has also involved other topics measuring the diboson production process whose final
states are similar to those of the Higgs boson process (this is an important step for designing
Higgs searches), the Bs oscillation, the lifetime of the top quark (by measuring its width),
the mass difference between the top and anti-top quarks, properties of the Z and W boson
(their production cross section and forward-backward asymmetry), and decay rates of bottom and charm mesons.
AMY Experiment at TRISTAN electron-positron collider (1986 - 1990)