HL-LHC sensitivity to higgsinos from natural SUSY with gravitino LSP

Jianpeng Dai; Song Li; Jin Min Yang; Yang Zhang; Pengxuan Zhu; Rui Zhu

doi:10.1140/epjc/s10052-024-13160-3

2024 Impact factor 4.8

Particles and Fields

Open Access

Eur. Phys. J. C (2024) 84: 781
https://doi.org/10.1140/epjc/s10052-024-13160-3

Regular Article - Theoretical Physics

HL-LHC sensitivity to higgsinos from natural SUSY with gravitino LSP

Jianpeng Dai¹^,2, Song Li¹^,2^b, Jin Min Yang¹^,3, Yang Zhang⁴, Pengxuan Zhu¹^,5^e and Rui Zhu¹^,2^f

¹ CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, 100190, Beijing, People’s Republic of China
² School of Physical Sciences, University of Chinese Academy of Sciences, 100049, Beijing, People’s Republic of China
³ School of Physics, Henan Normal University, 453007, Xinxiang, People’s Republic of China
⁴ School of Physics, Zhengzhou University, 450000, Zhengzhou, People’s Republic of China
⁵ ARC Centre of Excellence for Dark Matter Particle Physics, University of Adelaide, North Terrace, 5005, Adelaide, SA, Australia

^b lisong@itp.ac.cn
^e pengxuan.zhu@adelaide.edu.au
^f zhurui@itp.ac.cn

Received: 17 April 2024
Accepted: 23 July 2024
Published online: 6 August 2024

Abstract

In the realm of natural supersymmetric models, higgsinos are typically the lightest electroweakinos. In gauge-mediated supersymmetry breaking models, the lightest higgsino-dominated particles decay into a Z-boson or a Higgs boson (h), along with an ultra-light gravitino ( $\tilde{G}$ $\tilde{G}$ ) serving as the lightest supersymmetric particle (LSP). This scenario suggests a significant non-resonant hh production. Basing on the recent global fitting results of the $\tilde{G}$ $\tilde{G}$ -EWMSSM (MSSM with light electroweakinos and an eV-scale gravitino as the LSP) performed by the GAMBIT collaboration, which support a higgsino-dominated electroweakino as light as 140 GeV, we develop two simplified models to evaluate their detection potential at the high-luminosity LHC (HL-LHC) with $\sqrt{s} = 14 TeV$ $\sqrt{s} = 14~\textrm{TeV}$ and an integrated luminosity of $3000 {fb}^{- 1}$ $3000~\textrm{fb}^{-1}$ . The first model examines the processes where heavier higgsino-dominated states decay into soft W/Z bosons, while the second focuses on direct decays of all three higgsino-dominated electroweakinos into W/Z/h plus a $\tilde{G}$ $\tilde{G}$ . Our study, incorporating both models and their distinct decay channels, utilizes detailed Monte Carlo simulations for signals and standard model backgrounds. We find that the HL-LHC can probe higgsinos up to 575 GeV, potentially discovering or excluding the natural SUSY scenario in the context of a gravitino LSP. Further, we reinterpret this discovery potential using the GAMBIT global fit samples, and find that the entire parameter space of $| μ | \leq 500 GeV$ $|\mu | \le 500~\textrm{GeV}$ with an electroweak fine-tuning measure ( $Δ_{EW}$ $\Delta _{\textrm{EW}}$ ) under 100 in $\tilde{G}$ $\tilde{G}$ -EWMSSM is accessible at the HL-LHC.

© The Author(s) 2024

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