Spin determination via third generation cascade decays

Oram Gedalia, Seung Joon Lee, Gilad Perez

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Once new particles are discovered at the LHC and their masses are measured, it will be of crucial importance to determine their spin, in order to identify the underlying new physics model. We investigate the method first suggested by Barr and later extended by others to distinguish between supersymmetry and alternative models, e.g. universal extra dimensions, in a certain cascade decay. This method uses invariant mass distributions of the outgoing standard model particles to measure the spin of intermediate particles, by exploiting the quark/antiquark asymmetry of the LHC as a pp collider, which is limited for first generation quarks. In this work, we suggest instead to measure the charge of the outgoing quark, in case it is a third generation quark. The resulting asymmetry for a bottom quark is similar to the previous method, while it is independent of hadronic uncertainties. Furthermore, for a top quark, the asymmetry allows better distinction between the models, as demonstrated by a quantitative analysis of model discrimination. We also show that the top's decay products can be used instead of the top itself, when the reconstruction of the top momentum is difficult to accomplish, and still provide information about the spin.

Original languageEnglish
Article number035012
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Volume80
Issue number3
DOIs
Publication statusPublished - 2009 Aug 17
Externally publishedYes

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cascades
quarks
decay
asymmetry
mass distribution
quantitative analysis
supersymmetry
discrimination
momentum
physics
products

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)

Cite this

Spin determination via third generation cascade decays. / Gedalia, Oram; Lee, Seung Joon; Perez, Gilad.

In: Physical Review D - Particles, Fields, Gravitation and Cosmology, Vol. 80, No. 3, 035012, 17.08.2009.

Research output: Contribution to journalArticle

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