[Paper Review] Beyond the Standard Model Physics at the HL-LHC and HE-LHC

X. Cid Vidal, M. D’Onofrio+295 more|arXiv (Cornell University)|Dec 19, 2018

Particle physics theoretical and experimental studiesPhysics and Astronomy47 citations

TL;DR

This report surveys the potential for discovering or constraining Beyond the Standard Model physics at the HL-LHC (14 TeV, 3 ab^-1) and HE-LHC (27 TeV, 15 ab^-1) across a wide range of models, including SUSY, dark matter, long-lived particles, leptoquarks, sterile neutrinos, axion-like particles, and heavy resonances.

ABSTRACT

This is the third out of five chapters of the final report [1] of the Workshop on Physics at HL-LHC, and perspectives on HE-LHC [2]. It is devoted to the study of the potential, in the search for Beyond the Standard Model (BSM) physics, of the High Luminosity (HL) phase of the LHC, defined as $3~\mathrm{ab}^{-1}$ of data taken at a centre-of-mass energy of $14~\mathrm{TeV}$, and of a possible future upgrade, the High Energy (HE) LHC, defined as $15~\mathrm{ab}^{-1}$ of data at a centre-of-mass energy of $27~\mathrm{TeV}$. We consider a large variety of new physics models, both in a simplified model fashion and in a more model-dependent one. A long list of contributions from the theory and experimental (ATLAS, CMS, LHCb) communities have been collected and merged together to give a complete, wide, and consistent view of future prospects for BSM physics at the considered colliders. On top of the usual standard candles, such as supersymmetric simplified models and resonances, considered for the evaluation of future collider potentials, this report contains results on dark matter and dark sectors, long lived particles, leptoquarks, sterile neutrinos, axion-like particles, heavy scalars, vector-like quarks, and more. Particular attention is placed, especially in the study of the HL-LHC prospects, to the detector upgrades, the assessment of the future systematic uncertainties, and new experimental techniques. The general conclusion is that the HL-LHC, on top of allowing to extend the present LHC mass and coupling reach by $20-50\%$ on most new physics scenarios, will also be able to constrain, and potentially discover, new physics that is presently unconstrained. Moreover, compared to the HL-LHC, the reach in most observables will generally more than double at the HE-LHC, which may represent a good candidate future facility for a final test of TeV-scale new physics.

Motivation & Objective

• Assess the reach for a broad spectrum of Beyond the Standard Model scenarios at the HL-LHC and HE-LHC.
• Analyze detector upgrades, systematic uncertainties, and new experimental techniques relevant for future NP searches.
• Provide coordinated projections for supersymmetry, dark matter, long-lived particles, flavor, and resonance signatures.

Proposed method

• Use a mix of detailed detector performance studies and fast simulations to project object reconstruction under HL-LHC conditions.
• Interface simulated events with event generators and parton showers to estimate signal and background in various search channels.
• Apply scale factors based on cross sections and upgraded detector performance to extrapolate current analyses to HL-LHC/HE-LHC.
• Incorporate systematic uncertainty considerations guided by current analyses and projected improvements for large datasets.
• Summarize results within a unified framework spanning SUSY, DM/Dark Sectors, LLPs, flavour, and resonances.

Experimental results

Research questions

• RQ1 What is the projected reach for gluinos and third-generation squarks at HL-LHC and HE-LHC?
• RQ2 How do upgraded detectors and higher luminosity affect sensitivity to electroweakinos, sleptons, and compressed spectra?
• RQ3 What are the prospects for dark matter and dark sector signatures, including monojet, heavy flavour, and Higgs portal scenarios, at HL-LHC/HE-LHC?
• RQ4 What is the potential for discovering long-lived particles via displaced vertices, disappearing tracks, or heavy stable charged particles?
• RQ5 How do HL-LHC/HE-LHC projections constrain high-mass resonances and new gauge bosons across various models?

Key findings

• HL-LHC prospects extend the present mass and coupling reach by approximately 20-50% across many NP scenarios.
• HE-LHC reach generally more than doubles compared to HL-LHC for most observables, enhancing sensitivity to TeV-scale NP.
• The study emphasizes the importance of detector upgrades, systematic uncertainty treatment, and novel analysis techniques for improving NP sensitivity.
• A wide range of BSM signatures is covered, including SUSY top partners, electroweakinos, sleptons, dark matter channels, LLPs, leptoquarks, and heavy resonances.
• Results highlight potential discoveries or strong constraints on models that are currently unconstrained.