Jet Substructure Probe on Scalar Leptoquark Models via Top Polarization

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Main Authors: Ghosh, Anupam, Konar, Partha, Samui, Tousik, Singh, Ritesh K.
Format: Preprint
Published: 2025
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author Ghosh, Anupam
Konar, Partha
Samui, Tousik
Singh, Ritesh K.
author_facet Ghosh, Anupam
Konar, Partha
Samui, Tousik
Singh, Ritesh K.
contents The study of leptoquarks and their couplings to fermions with different chiralities provides a powerful tool for distinguishing among different leptoquark models. As a case study, we focus on two specific third-generation scalar leptoquark models, $S_3$ and $R_2$, which differ in their electroweak quantum numbers and chiral structures of couplings to the top quark, leading to distinct top-quark polarization states. To enhance the efficacy of the analysis, we employ jet substructure techniques like Soft Drop, $N$-subjettiness, and our custom $b$-tagging method, along with other event variables. The analysis has been performed using both fixed radius and dynamic radius jet clustering algorithms. A multivariate analysis using a boosted decision tree (BDT) is performed to isolate signal from the Standard Model background. For a leptoquark mass of 1250 GeV, the analysis achieves a signal significance of up to $5.3\,σ$ at the 14 TeV HL-LHC. Furthermore, a $CL_s$-based profile likelihood estimator is applied to polarization-sensitive variables to discriminate between the two models. To enhance separation between the two models, an additional BDT classifier score is obtained by training a BDT network to distinguish between the $S_3$ and $R_2$ models. In the chosen signal region, the BDT classifier score provides a separation score of up to $3.2\,σ$, outperforming traditional variables such as $E_b/E_t$ and $\cosθ_b$.
format Preprint
id arxiv_https___arxiv_org_abs_2505_16328
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Jet Substructure Probe on Scalar Leptoquark Models via Top Polarization
Ghosh, Anupam
Konar, Partha
Samui, Tousik
Singh, Ritesh K.
High Energy Physics - Phenomenology
The study of leptoquarks and their couplings to fermions with different chiralities provides a powerful tool for distinguishing among different leptoquark models. As a case study, we focus on two specific third-generation scalar leptoquark models, $S_3$ and $R_2$, which differ in their electroweak quantum numbers and chiral structures of couplings to the top quark, leading to distinct top-quark polarization states. To enhance the efficacy of the analysis, we employ jet substructure techniques like Soft Drop, $N$-subjettiness, and our custom $b$-tagging method, along with other event variables. The analysis has been performed using both fixed radius and dynamic radius jet clustering algorithms. A multivariate analysis using a boosted decision tree (BDT) is performed to isolate signal from the Standard Model background. For a leptoquark mass of 1250 GeV, the analysis achieves a signal significance of up to $5.3\,σ$ at the 14 TeV HL-LHC. Furthermore, a $CL_s$-based profile likelihood estimator is applied to polarization-sensitive variables to discriminate between the two models. To enhance separation between the two models, an additional BDT classifier score is obtained by training a BDT network to distinguish between the $S_3$ and $R_2$ models. In the chosen signal region, the BDT classifier score provides a separation score of up to $3.2\,σ$, outperforming traditional variables such as $E_b/E_t$ and $\cosθ_b$.
title Jet Substructure Probe on Scalar Leptoquark Models via Top Polarization
topic High Energy Physics - Phenomenology
url https://arxiv.org/abs/2505.16328