Top polarization in stop production at the LHC

Belanger, Genevieve and Godbole, RM and Hartgring, L and Niessen, I (2013) Top polarization in stop production at the LHC. In: JOURNAL OF HIGH ENERGY PHYSICS (5).

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Abstract

We survey the expected polarization of the top produced in the decay of a scalar top quark, t -> t((chi) over tildei)(0), i = 1 - 2. The phenomenology is quite interesting, since the expected polarization depends both on the mixing in the stop and neutralino sectors and on the mass differences between the stop and the neutralino. We find that a mixed stop behaves almost like a right-handed stop due to the larger hypercharge that enters the stop/top/gaugino coupling and that these polarisation effects disappear, when m((t) over tilde1) approximate to m(t) +m((chi) over tildei)(0). After a discussion on the expected top polarization from the decay of a scalar top quark, we focus on the interplay of polarization and kinematics at the LHC. We discuss different probes of the top polarization in terms of lab-frame observables. We find that these observables faithfully reflect the polarization of the parent top-quark, but also have a non-trivial dependence on the kinematics of the stop production and decay process. In addition, we illustrate the effect of top polarization on the energy and transverse momentum of the decay lepton in the laboratory frame. Our results show that both spectra are softened substantially in case of a negatively polarized top, particularly for a large mass difference between the stop and the neutralino. Thus, the search strategies, and the conclusions that can be drawn from them, depends not just on the mass difference m((t) over tilde) - m((chi) over tildei)(0) due to the usual kinematic effects but also on the effects of top polarization on the decay kinematics the extent of which depends in turn on the said mass difference.

Item Type:	Journal Article
Publication:	JOURNAL OF HIGH ENERGY PHYSICS
Publisher:	SPRINGER
Additional Information:	Copyright of this article is belongs to SPRINGER
Keywords:	Supersymmetry Phenomenology
Department/Centre:	Division of Physical & Mathematical Sciences > Centre for High Energy Physics
Date Deposited:	25 Sep 2013 12:02
Last Modified:	27 Feb 2019 05:33
URI:	http://eprints.iisc.ac.in/id/eprint/47323

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