Long-Lived Gluinos and Stable Axinos.

Area of Science:

• High Energy Physics
• Particle Physics
• Cosmology

Background:

• Supersymmetric (SUSY) models predict new particles, including gluinos.
• The properties and detection of long-lived particles are crucial for understanding beyond-the-Standard-Model physics.
• Previous constraints on gluino masses were significant.

Purpose of the Study:

• To present a novel scenario for "long-lived" gluinos in supersymmetric models.
• To explore reduced mass bounds for gluinos when they are the lightest ordinary supersymmetric particle (LOSP).
• To identify optimal detection strategies for these long-lived gluinos.

Main Methods:

• Investigating supersymmetric models where the gluino is the lightest ordinary supersymmetric particle (LOSP) and the axino is the lightest supersymmetric particle.
• Analyzing the impact of the axion decay constant (f_{a}) on gluino mass bounds.
• Simulating the detection of decaying R hadrons, specifically gluino decays to a gluon and axino in calorimeters.

Main Results:

• Gluino mass bounds can be reduced to below 1000 GeV for specific axion decay constant ranges (f_{a}<1×10^{10} GeV).
• Decaying R hadrons, with gluinos decaying into a gluon and axino, provide the most effective limits.
• The gluino LOSP scenario is viable in mirage mediation and general gauge-mediated SUSY breaking models.

Conclusions:

• The proposed scenario allows for lighter gluinos than previously constrained.
• Detecting decaying R hadrons is a promising experimental approach for discovering these particles.
• In this framework, axions or axinos emerge as viable dark matter candidates.