Rhadron

Rhadron, in particle physics, refers to a hypothetical hadron-like bound state that contains at least one supersymmetric particle (typically a gluino or a squark) bound with standard-model quarks or gluons. These states arise in supersymmetric extensions of the Standard Model where the SUSY particle is long-lived or is the lightest colored state. R-hadrons would hadronize after production in high-energy collisions and need not decay promptly, depending on the model and the conservation of R-parity.

R-hadrons can be broadly classified as meson-like or baryon-like. Meson-like R-hadrons consist of a SUSY particle bound with a quark-antiquark pair, while baryon-like R-hadrons contain the SUSY particle bound with three quarks. If a squark is the lightest colored SUSY state, analogous bound states with antiquarks or with gluons can also form. The precise mass spectrum and charge states depend on the underlying SUSY model and on nonperturbative QCD dynamics.

Phenomenology and detection focus on distinctive collider signatures. Because R-hadrons are typically heavy, they may be slow-moving and highly ionizing, leading to time-of-flight and energy-loss anomalies. They can undergo charge exchange while traversing detector material, further complicating identification. Searches at the Large Hadron Collider look for heavy stable charged particles, displaced vertices, or unusual calorimeter and tracking responses. Cosmological and astrophysical constraints also inform their viability. No experimental confirmation exists to date; R-hadrons remain a speculative but actively studied possibility in beyond-Standard-Model phenomenology.