Young-Kee Kim in the Library for Symmetry
8/1/2005

Young-Kee Kim: Research

As a particle experimentalist, my main physics interest is to understand the orgin of mass, one of the central questions in particle physics. At this moment, a large fraction of my research is being done at the CDF experiment with the Tevatron, currently the world's highest energy accelerator, colliding protons with antiprotons at a center-of-mass energy of 2 trillion volts (TeV). In 1995, we, along with the sister experiment DZero, discovered the sixth and perhaps final quark, called the top quark. My group has played a major role in the detector construction and operation, and the data analysis (Higgs searches, top and bottom quark physics, and W boson physics). As we approach the start of the LHC, the will-be world's highest energy accelerator from 2009, colliding protons with protons at a center-of-mass energy of 14 TeV, my research effort is being shifted toward the ATLAS experiment (Higgs searches and Trigger development) at the LHC. My research program also includes the improvement of the collision rate for the LHC accelerator with a novel technique called crystal collimation.

To understand the orgin of mass, the emphasis of my research has been

searches for the Higgs boson which is responsible for giving masses to elementary particles
precision measurements of the mass of the top quark (nature's heaviest quark) and the mass of the W boson (carrier of weak force, responsible for radioactive decays). Through quantum corrections, these measurements provide information about the mass of the Higg boson.

Other analysis topics include the lifetime measurement of the top quark, properties of the bottom quark, in particular its ability to mix into its antiparticle (an important measurement for understanding the phenomena of the asymmetry between matter and anti-matter), and the rare decay processes such as D_s → μ⁺μ^- (sensitive to new physics beyond the Standard Model).

Tevatron: 2 TeV proton-antiproton collider

CDF Experiment: Current Effort

Higgs Searches
- H → τ⁺τ^-
  - Kohei Yorita (postdoc) Results
- ZH → 2 neurinos + 2 b quarks
  - Wes Ketchum (2nd year grad.)
- ZH → 2 leptons + 2 b quarks
  - Zaid Alawi, Jon Poage, Junghyun Lee (undergraduate)
Top Quark Physics
- Top Quark Mass
  - Wojtek Fedorko (Ph.D. Thesis - Sept.2008), Results
  - Jian Tang (2nd year grad.)
- Top Quark Lifetime
  - Satomi Shiraishi (2nd year grad.) Publication, Results
W Boson Physics
- W Boson Mass: Derek Thompson
New Phenomena
- D_s → μ⁺μ^- Decay Rate: Edmund Berry Results

LHC: 14 TeV proton-proton collider

ATLAS Experiment: Current Effort

Data Analysis Strategy
1. Understanding Z and W at LHC
  - Z and Z' → μ⁺μ^-: John Dougherty (undergrad.)
  - W → eν, μν, and W (→ eν, μν) + jets
2. Rediscovering Top at LHC, Studying Top
  - tt-bar → Wb + Wb → eν/μν + 4 jets
3. Searching for Higgs
Hardware: Tracking Trigger
- Hyunsu Lee (postdoc), Kohei Yorita (postdoc, now faculty at Waseda University)
- CDF Analysis students (Wes Ketchum, Jian Tang)

Looking for graduate students for ATLAS

LHC Accelerator

Crystall Collimation Project to improve the luminosity: Satomi Shiraishi (2nd year graduate student) analysis