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Measurement of R(D) and R(D*) Using Semileptonic Tags and Hadronic τ Decays


Kim, Jae Hong (2019) Measurement of R(D) and R(D*) Using Semileptonic Tags and Hadronic τ Decays. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/KF89-DS18.


We present a measurement of R(D(*)) = B(B → D̅(*) τντ)/B(B → D̅(*) ℓν) using semileptonic tagging and hadronic τ decays on the 433 fb-1 of data collected at the Υ(4S) resonance using the BaBar detector at the PEP-II collider. We obtain a high statistics data sample using loose selection criteria. The signal is extracted by performing a 2-dimensional fit of the component densities to the kernel density estimate of the data, which is made computationally tractable by algorithmic improvements and speedups provided by graphics processing units. We obtain two distinct central values based on the model used to represent the BB̅ background densities: R(D) = 0.231 ± 0.028 ± 0.028 and R(D*) = 0.127 ± 0.019 ± 0.031 with a correlation of 0.06 and R(D) = 1.454 ± 0.028 ± 0.028 and R(D*) = 1.507 ± 0.019 ± 0.031 with a correlation of 0.06. The region encompassed by the two results are consistent with both the Standard Model prediction and the world average.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:BaBar; High Energy Physics; B Meson Decays
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Minor Option:Computer Science
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Hitlin, David G.
Thesis Committee:
  • Porter, Frank C. (chair)
  • Hitlin, David G.
  • Patterson, Paul H.
  • Simmons-Duffin, David
Defense Date:15 January 2019
Record Number:CaltechTHESIS:01252019-144433241
Persistent URL:
Kim, Jae Hong0000-0003-1968-2753
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11364
Deposited By: Jae Hong Kim
Deposited On:04 Feb 2019 22:11
Last Modified:04 Oct 2019 00:24

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