Hunting scalar leptoquarks with boosted tops and light leptons

• Published in: arXiv.org 2019-09
• Main Authors: Chandak, Kushagra, Mandal, Tanumoy, Mitra, Subhadip
• Format: Article
• Language: English
• Subjects: Channels; Coupling; Hunting; Large Hadron Collider; Leptons; Quarks; Search methods
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1907.11194

The LHC search strategies for leptoquarks that couple dominantly to a top quark are different than for the ones that couple mostly to the light quarks. We consider charge \(1/3\) (\(\phi_1\)) and \(5/3\) (\(\phi_5\)) scalar leptoquarks that can decay to a top quark and a charged lepton (\(t\ell\)) giving rise to a resonance system of a boosted top and a high-\(p_{\rm T}\) lepton. We introduce simple phenomenological models suitable for bottom-up studies and explicitly map them to all possible scalar leptoquark models within the Buchm\"{u}ller-R\"{u}ckl-Wyler classifications that can have the desired decays. We study pair and single productions of these leptoquarks. Contrary to the common perception, we find that the single production of top-philic leptoquarks \(\phi = \{\phi_1,\phi_5\}\) in association with a lepton and jets could be significant for order one \(\phi t\ell\) coupling in certain scenarios. We propose a strategy of selecting events with at least one hadronic-top and two high-\(p_{\rm T}\) same flavour opposite sign leptons. This captures events from both pair and single productions. Our strategy can significantly enhance the LHC discovery potential especially in the high-mass region where single productions become more prominent. Our estimation shows that a scalar leptoquark as heavy as \(\sim1.7\) TeV can be discovered at the \(14\) TeV LHC with 3 ab\(^{-1}\) of integrated luminosity in the \(t\ell\ell+X\) channel for \(100\%\) branching ratio in the \(\phi\to t\ell \) decay mode. However, in some scenarios, the discovery reach can increase beyond \(2\) TeV even though the branching ratio comes down to about \(50\%\).