Threshold effects in the decay of heavy b and t quarks

Yuan Chao, Kai-Feng Chen, Shing-Kuo Chen, Wei-Shu Hou, Bo-Yan Huang, and Yeong-Jyi Lei
Phys. Rev. D 84, 014029 – Published 22 July 2011

Abstract

A sequential fourth generation is still viable, but the t and b quarks are constrained not to be too far apart in mass. The tbW and btW decay channels are still being pursued at the Tevatron, which will soon be surpassed by the LHC. We use a convolution method with up to five-body final states to study t and b decays. We show how the two decay branches for mb below the tW threshold, btW* and t*W, merge with btW above the threshold. We then consider the heavy-to-heavy transitions bt(*)W(*) (or tb(*)W(*)), as they are not suppressed by quark mixing. We find that, because of the threshold sensitivity of the branching fraction of tbW* (or btW*), it is possible to measure the strength of the CKM mixing element Vtb (or Vtb), especially when it is rather small. We urge experimenters to pursue and separate the tbW* (or btW*) decay in their search programs.

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  • Received 30 December 2010

DOI:https://doi.org/10.1103/PhysRevD.84.014029

© 2011 American Physical Society

Authors & Affiliations

Yuan Chao1, Kai-Feng Chen1, Shing-Kuo Chen1, Wei-Shu Hou1,2, Bo-Yan Huang1, and Yeong-Jyi Lei1

  • 1Department of Physics, National Taiwan University, Taipei 10617, Taiwan
  • 2National Center for Theoretical Sciences, National Taiwan University, Taipei 10617, Taiwan

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Vol. 84, Iss. 1 — 1 July 2011

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