Abstract

Search strategies for the third-generation leptoquarks (LQs) are distinct from other LQ searches, especially when they decay to a top quark and a $\tau$ lepton. We investigate the cases of all TeV-scale scalar and vector LQs that decay to either a top-tau pair (charge-$1/3$ and $5/3$ LQs) or a top-neutrino pair (charge-$2/3$ LQs). One can then use the boosted top (which can be tagged efficiently using jet-substructure techniques) and high-$p_{\rm T}$ $\tau$ leptons to search for these LQs. We consider two search channels with either one or two taus along with at least one hadronically decaying boosted top quark. We estimate the high luminosity LHC (HL-LHC) search prospects of these LQs by considering both symmetric and asymmetric pair and single production processes. Our selection criteria are optimised to retain events from both pair and single production processes. The combined signal has better prospects than the traditional searches. We include new three-body single production processes to enhance the single production contributions to the combined signal. We identify the interference effect that appears in the dominant single production channel of charge-$1/3$ scalar LQ ($S^{1/3}$). This interference is constructive if $S^{1/3}$ is weak-triplet and destructive, for a singlet one. As a result, their LHC prospects differ appreciably.

Highlights

  • Leptoquarks (LQs) are receiving a lot of attention in the literature

  • III, we discuss the Large Hadron Collider (LHC) phenomenology and illustrate our search strategy, and we present our estimations in Sec

  • We have considered all scalar and vector LQs that can decay to tτ or tν pair

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Summary

INTRODUCTION

Leptoquarks (LQs) are receiving a lot of attention in the literature. Since they connect the quark and the lepton sectors of the Standard Model (SM), their phenomenology is interesting in general. In a previous paper [43], we argued that it is possible to improve the LHC discovery prospect of LQs (or any other new colored particles, for that matter) or exclusion limits if we systematically combine pair and single production channels In this case, the two signatures capture combinations of pair and single production processes in. We have found an important point; for the same strength of the LQ couplings and decays, the HL-LHC discovery reach for the charge-1=3 component of the triplet scalar S3 is higher than that of the singlet S1, another charge-1=3 sLQ This happens because of constructive interference among some subprocesses in the pp → S13=3τj single production process.

SCALAR AND VECTOR LEPTOQUARK MODELS
Scalar leptoquark models
Vector leptoquark models
Simplified models and benchmark scenarios
LHC PHENOMENOLOGY AND SEARCH STRATEGY
Production at the LHC
Signal topologies and the background
Background processes
Analysis
HL-LHC PROSPECTS
Findings
SUMMARY AND CONCLUSIONS
Full Text
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