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Title: A precise measurement of the top quark mass in dilepton final states using 9.7 fb$$^{-1}$$ of D{Ø} Run II data

The top quark is a very special fundamental particle in the Standard Model (SM) mainly due to its heavy mass. The top quark has extremely short lifetime and decays before hadronization. This reduces the complexity for the measurement of its mass. The top quark couples very strongly to the Higgs boson since the fermion-Higgs Yukawa coupling linearly depends on the fermion’s mass. Therefore, the top quark is also heavily involved in Higgs production and related study. A precise measurement of the top quark mass is very important, as it allows for self-consistency check of the SM, and also gives a insight about the stability of our universe in the SM context. This dissertation presents my work on the measurement of the top quark mass in dilepton final states of t$$\bar{t}$$ events in p$$\bar{p}$$ collisions at √s = 1.96 TeV, using the full DØ Run II data corresponding to an integrated luminosity of 9.7 fb -1 at the Fermilab Tevatron. I extracted the top quark mass by reconstructing event kinematics, and integrating over expected neutrino rapidity distributions to obtain solutions over a scanned range of top quark mass hypotheses. The analysis features a comprehensive optimization that I made to minimize the expected statistical uncertainty. I also improve the calibration of jets in dilepton events by using the calibration determined in t$$\bar{t}$$ → lepton+jets events, which reduces the otherwise limiting systematic uncertainty from the jet energy scale. The measured mass is 173.11 ± 1.34(stat) +0.83 -0.72(sys) GeV .
  1. Southern Methodist Univ., Dallas, TX (United States)
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Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
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USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Country of Publication:
United States