[Paper Review] Particle and Astroparticle Searches for Supersymmetry

Jonathan L. Feng, K. Matchev+1 more|arXiv (Cornell University)|Nov 22, 2001

Particle physics theoretical and experimental studies3 citations

TL;DR

This paper presents a comprehensive analysis of particle and astroparticle probes for supersymmetry within the minimal supergravity framework, emphasizing the complementarity of collider, low-energy precision, direct, and indirect dark matter searches. It shows that combined experiments can probe nearly all cosmologically preferred supersymmetric models, and that if supersymmetry is realized at the weak scale with neutralino dark matter, observable signals must appear before the LHC begins operation—particularly if superpartners are light enough for a 500 GeV linear collider to detect them.

ABSTRACT

Supersymmetry may be discovered at high energy colliders, through low energy precision measurements, and by dark matter searches. We present a comprehensive analysis of all available probes in minimal supergravity. This work extends previous analyses by including the focus point branch of parameter space and the full array of promising indirect dark matter searches. We find that particle and astrophysical searches underway are highly complementary: each separately provides only partial coverage of the available parameter space, but together they probe almost all models. Cosmology does {\em not} provide upper bounds on superpartner masses useful for future colliders. At the same time, in the cosmologically preferred region, if supersymmetry is to be observable at a 500 GeV linear collider, some signature of supersymmetry must appear {\em before} the LHC.

Motivation & Objective

• To assess the full complement of particle and astroparticle probes for supersymmetry in the minimal supergravity framework.
• To extend prior analyses by including the focus point region of parameter space, which features unique dark matter properties.
• To evaluate the sensitivity of indirect dark matter searches—such as neutrino, gamma-ray, and antimatter detection—alongside direct and collider probes.
• To determine whether future experiments can cover the full range of cosmologically preferred supersymmetric models before the LHC begins.
• To establish whether a 500 GeV linear collider can observe supersymmetry only if signals appear earlier in other experiments.

Proposed method

• Uses the minimal supergravity (mSUGRA) framework as a conservative benchmark for supersymmetry phenomenology.
• Incorporates the focus point region of mSUGRA parameter space, where the lightest neutralino has a significant Higgsino component.
• Evaluates constraints and sensitivities from multiple experimental probes: LEP, Tevatron, B-factory $B\to X_s\gamma$, $g_\mu-2$, direct dark matter detectors (CDMS, CRESST, GENIUS), and indirect searches (neutrinos, gamma rays, positrons, antiprotons).
• Projects experimental reach using sensitivity thresholds from Table 1, including limits on chargino masses, $B\to X_s\gamma$ branching ratios, muon anomalous magnetic moment, and fluxes of secondary particles from neutralino annihilation.
• Applies halo model-dependent bounds for gamma rays from the galactic center, assuming a moderate profile ($\bar{J}=500$).
• Combines results across all probes to assess total coverage of the mSUGRA parameter space, particularly in regions with $\Omega_\chi h^2 \in [0.1, 0.3]$.

Experimental results

Research questions

• RQ1 Can the full range of cosmologically preferred supersymmetric models be probed by current and near-future experiments before the LHC begins?
• RQ2 How do indirect dark matter searches—especially those detecting neutrinos, gamma rays, and antimatter—complement traditional collider and low-energy precision measurements?
• RQ3 What are the implications for a 500 GeV linear collider if supersymmetry is to be discovered at the weak scale with neutralino dark matter?
• RQ4 Why is the focus point region of mSUGRA particularly promising for indirect dark matter detection?
• RQ5 Under what conditions might supersymmetry evade detection across all current and planned experiments?

Key findings

• Particle and astrophysical searches are highly complementary: no single probe covers the full parameter space, but their combination probes nearly all cosmologically preferred models.
• In the focus point region, neutralinos have a significant Higgsino component, making them maximally sensitive to indirect dark matter searches such as neutrino and gamma-ray detection.
• For $\tan\beta = 10$, all cosmologically preferred models yield observable signals in at least one experiment before the LHC begins operation.
• For $\tan\beta = 50$, a small region of parameter space with $M_{1/2} \gtrsim 450~{\rm GeV}$ and $m_0 \gtrsim 1.5~{\rm TeV}$ escapes detection, but this requires significant fine-tuning and is disfavored by naturalness.
• If supersymmetry is realized at the weak scale with neutralino dark matter, a 500 GeV linear collider can only observe superpartners if signals appear in other experiments before LHC operation—this conclusion holds independently of naturalness.