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Measuring R(D(*)) for B → ‾D(*)τν_τ using Semileptonic Tags and Tau Decays to Hadrons


Chao, Daniel Shuteh (2018) Measuring R(D(*)) for B → ‾D(*)τν_τ using Semileptonic Tags and Tau Decays to Hadrons. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/25e6-j889.


We perform a measurement of R(D(*)) for B → D(*)τντ using semileptonic tagging and τ decays to hadrons on the 429 fb-1 of data that BABAR collected at the Υ(4S) resonance. This is the first measurement of R(D(*)) using the specied reconstruction channels. Candidate selection was performed with supervised learning, where the training labels were obtained by solving an instance of subgraph isomorphism. The signal extraction was performed by solving an optimization problem whose objective function required the evaluation of kernel density estimates that were accelerated by a branch-and-bound algorithm as well as with a GPU. The training data for the density estimates were themselves the output of two classier scores. We present a 68% and 95% confidence regions of R(D(*)), which do not show enough evidence to reject the standard model prediction.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Babar, High Energy Physics, Supersymmetry
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):
  • Porter, Frank C.
Thesis Committee:
  • Porter, Frank C. (chair)
  • Hitlin, David G.
  • Carroll, Sean M.
  • Yue, Yisong
Defense Date:8 September 2016
Record Number:CaltechTHESIS:04092018-211419944
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10797
Deposited By: Daniel Chao
Deposited On:08 May 2018 20:24
Last Modified:04 Oct 2019 00:20

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