Measuring Top-Quark Polarization in Top-Pair + Missing-Energy Events

Edmond L. Berger, Qing-Hong Cao, Jiang-Hao Yu, and Hao Zhang
Phys. Rev. Lett. 109, 152004 – Published 9 October 2012

Abstract

The polarization of a top quark can be sensitive to new physics beyond the standard model. Since the charged lepton from top-quark decay is maximally correlated with the top-quark spin, it is common to measure the polarization from the distribution in the angle between the charged lepton and the top-quark directions. We propose a novel method based on the charged lepton energy fraction and illustrate the method with a detailed simulation of top-quark pairs produced in supersymmetric top squark pair production. We show that the lepton energy ratio distribution that we define is very sensitive to the top-quark polarization but insensitive to the precise measurement of the top-quark energy.

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  • Received 6 July 2012

DOI:https://doi.org/10.1103/PhysRevLett.109.152004

© 2012 American Physical Society

Authors & Affiliations

Edmond L. Berger2, Qing-Hong Cao1, Jiang-Hao Yu3, and Hao Zhang2,4

  • 1Department of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, China
  • 2High Energy Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
  • 3Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
  • 4Illinois Institute of Technology, Chicago, Illinois 60616-3793, USA

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Issue

Vol. 109, Iss. 15 — 12 October 2012

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