PoS - Proceedings of Science
Volume 364 - European Physical Society Conference on High Energy Physics (EPS-HEP2019) - Top and Electroweak Physics
Boosted Top quark polarization
A. Holur Vijay
Full text: Not available
Abstract
In top quark production, the polarization of top quarks, decided by the chiral structure of couplings, is likely to be modified in the presence of any new physics contribution to the production.
Hence it is a good discriminator for those new physics models wherein the couplings have a chiral structure different than that in the Standard Model (SM). In this note we construct probes of
the polarization of a top quark decaying hadronically, using easily accessible kinematic variables
such as the energy fraction or angular correlations of the decay products. Tagging the boosted top
quark using jet sub structure technique, we study robustness of these observables for a benchmark
process, $W' → tb$. We demonstrate that the energy fraction of b-jet in the laboratory frame and
a new angular variable, constructed by us in the top rest frame, are both very powerful tools to
discriminate between the left and right polarized top quarks. Based on the polarization sensitive
angular variables, we construct asymmetries which reflect the polarization. We study the efficacy
of these variables for a new physics processes which give rise to boosted top quarks from the
decay of the top squark in the context of supersymmetry searches. Remarkably, it is found that
the asymmetry can vary over a wide range about +20% to -20%. The dependence of asymmetry
on top quark couplings of the new particles present in these models beyond the SM (BSM) is also
investigated in detail.
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