[Paper Review] Higgs Properties and Supersymmetry: Constraints and Sensitivity from the LHC to an $e^+e^-$ Collider

B. Bilki, M. Battaglia+4 more|arXiv (Cornell University)|Dec 31, 2021

Particle physics theoretical and experimental studies2 citations

TL;DR

This paper investigates how precision measurements of the Higgs boson's mass and couplings at the LHC and future $e^+e^-$ colliders constrain the parameter space of the phenomenological Minimal Supersymmetric Standard Model (pMSSM). Using scans of the 19-parameter pMSSM space, it shows that Higgs coupling measurements exclude 20% of viable pMSSM points at future $e^+e^-$ collider accuracy, with indirect sensitivity to the pseudoscalar Higgs mass $M_A$ reaching up to 1.4 TeV.

ABSTRACT

The study of the Higgs boson properties offers compelling perspectives for testing the effects of physics beyond the Standard Model and has deep implications for the LHC program and future colliders. Accurate determinations of the Higgs boson properties can provide us with a distinctively precise picture of the Higgs sector, set tight bounds, and predict ranges for the values of new physics model parameters. In this paper, we discuss the constraints on supersymmetry that can be derived by a determination of the Higgs boson mass and couplings. We quantify these constraints by using scans of the 19-parameter space of the so-called phenomenological minimal supersymmetric Standard Model. The fraction of scan points that can be excluded by the Higgs measurements is studied for the coupling measurement accuracies obtained in LHC Run 2 and expected for the HL-LHC program and $e^+e^-$ colliders and contrasted with those derived from missing transverse energy searches at the LHC and from dark matter experiments.

Motivation & Objective

• To assess the constraints on supersymmetry derived from precision Higgs boson property measurements.
• To compare the sensitivity of Higgs coupling measurements to those from direct LHC searches (e.g., missing transverse energy) and dark matter experiments.
• To quantify how future $e^+e^-$ colliders can indirectly probe the pseudoscalar Higgs mass $M_A$ in the pMSSM.
• To evaluate the interplay between Higgs measurements, direct SUSY searches, and flavor/DM constraints in narrowing down viable pMSSM parameter space.

Proposed method

• Conducted scans over the 19-parameter pMSSM parameter space to generate viable model points.
• Evaluated Higgs coupling modifiers $\kappa_i$ and their deviations from SM predictions due to SUSY contributions.
• Quantified the fraction of pMSSM points excluded by Higgs measurements at different experimental accuracies: LHC Run 2, HL-LHC, and future $e^+e^-$ colliders.
• Compared exclusion power of Higgs measurements to that of direct SUSY searches (MET), flavor physics, and dark matter experiments.
• Used theoretical and parametric uncertainties in Higgs production and decay rates alongside experimental accuracies.
• Assessed indirect sensitivity to $M_A$ via deviations in Higgs couplings, estimating reconstruction accuracy at future $e^+e^-$ colliders.

Experimental results

Research questions

• RQ1 How effective are Higgs coupling measurements in constraining the pMSSM parameter space compared to direct LHC searches and dark matter experiments?
• RQ2 What is the indirect sensitivity of future $e^+e^-$ colliders to the pseudoscalar Higgs mass $M_A$ through Higgs coupling measurements?
• RQ3 To what extent do loop corrections from SUSY particles (e.g., $\Delta_b$, $\Delta_t$, $\Delta_\tau$) affect Higgs couplings in the pMSSM?
• RQ4 How do theoretical and parametric uncertainties impact the interpretation of Higgs measurements in the context of new physics?
• RQ5 What fraction of pMSSM points survive all current constraints, and how much further reduction is achieved by future Higgs precision?

Key findings

• Higgs coupling measurements at LHC Run 2 accuracy exclude approximately 2% of the total pMSSM scan points.
• At HL-LHC accuracy, Higgs measurements exclude about 8% of the total pMSSM points.
• With future $e^+e^-$ collider accuracy, Higgs measurements exclude up to 20% of the total pMSSM points.
• For pMSSM points not yet excluded by flavor physics or direct LHC Higgs searches, Higgs measurements exclude 12% at future $e^+e^-$ collider accuracy.
• The indirect sensitivity to the pseudoscalar Higgs mass $M_A$ improves from ~450 GeV at LHC Run 2 to ~800 GeV at HL-LHC and up to ~1400 GeV at future $e^+e^-$ colliders.
• Future $e^+e^-$ colliders can reconstruct $M_A$ with relative accuracies ranging from ~8% to 40% for $M_A$ values from 700 GeV to 1.1 TeV, based on deviations in Higgs couplings from SM expectations.