Ravina, B. , Simpson, E. and Howarth, J. (2021) Observing tt¯ Z spin correlations at the LHC. European Physical Journal C, 81(9), 809. (doi: 10.1140/epjc/s10052-021-09605-8)
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Abstract
Spin correlations in the production of top-antitop quark (tt¯) pairs at the Large Hadron Collider (LHC) are an experimentally verified prediction of the Standard Model. In this paper, we compute the full spin density matrix for tt¯Z production at next-to-leading order precision in QCD, for center-of-mass energies of 13 and 14 TeV. We find that the additional emission of a Z boson leads to significantly different spin correlations with respect to the tt¯ case, and induces small longitudinal polarisations of the top quarks. We further propose an analysis strategy that could lead to the observation of spin correlations in tt¯Z events at the end of Run 3 of the LHC, or possibly earlier by combining the ATLAS and CMS datasets. In addition, we show that the pure angular information contained in the spin density matrix provides novel constraints on the dimension-6 effective field theory operators relevant to the t-Z interaction, without any reference to the total production rates.
| Item Type: | Articles |
|---|---|
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Ravina, Mr Baptiste and Simpson, Ethan and Howarth, Dr James |
| Authors: | Ravina, B., Simpson, E., and Howarth, J. |
| College/School: | College of Science and Engineering > School of Physics and Astronomy |
| Journal Name: | European Physical Journal C |
| Publisher: | Springer |
| ISSN: | 1434-6044 |
| ISSN (Online): | 1434-6052 |
| Published Online: | 13 September 2021 |
| Copyright Holders: | Copyright © 2021 The Authors |
| First Published: | First published in European Physical Journal C 81(9): 809 |
| Publisher Policy: | Reproduced under a Creative Commons License |
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