Abstract
We examine the compressed mass spectrum with sub-TeV top squark left(tilde{t}right) as lightest colored (s)particle in natural supersymmetry (SUSY). Such spectra are searched along with an additional hard jet, not only to boost the soft decay particles, also to yield enough missing transverse momentum. Several interesting kinematic variables are proposed to improve the probe performance for this difficult region, where we concentrate on relatively clean dileptonic channel of the top squark decaying into lightest neutralino (χ10), which is also the lightest supersymmetric particle. In this work, we investigate the merit of these kinematic variables, sensitive to compressed mass region extending the search by introducing additional states, chargino and slepton (sneutrino) having masses in between the tilde{t} and χ10. Enhanced production and lack of branching suppression are capable of providing a strong limit on chargino and slepton/sneutrino mass along with top squark mass. We perform a detailed collider analysis using simplified SUSY spectrum and found that with the present LHC data {M}_{tilde{t}} can be excluded up to 710 GeV right away for {M}_{upchi_1^0} of 640 GeV for a particular mass gap between different states.
Highlights
JHEP04(2018)024 dark matter [5, 6]
We examine the compressed mass spectrum with sub-TeV top squark (t) as lightest colored (s)particle in natural supersymmetry (SUSY)
We investigate the merit of these kinematic variables, sensitive to compressed mass region extending the search by introducing additional states, chargino and slepton having masses in between the tand χ01
Summary
We consider a scenario where the top squark decays predominantly through the dileptonic decay mode. These assumptions are made to ensure an enhanced production of signal events and avoid the production of very soft final state particles leading to efficient detection. We considered two new and simple kinematic variables which are very effective in the compressed region in discriminating signal and background These variables were earlier proposed in our previous work [56] where we have studied the four body decay of the top squark in the dileptonic channel. Arguments should suffice to demonstrate that the consecutive application of equal-velocity approximations cancel the mass dependence of intermediate states, so that the final algebraic relation remains as proposed in [56] These variables are well suited to study the signature considered here. We show how these variables can be used to minimize the backgrounds
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