Limits on Split Supersymmetry from Gluino Cosmology
4/22/2005
108 citations (99 excluding self-citations). Established cosmological constraints on split supersymmetry that complement the collider signatures explored in “Stopping Gluinos.”
The Problem
Split supersymmetry predicts long-lived gluinos because their decay to quarks is mediated by very heavy virtual squarks. If the squark mass is high enough, the gluino lifetime can exceed the timescale of big bang nucleosynthesis (BBN), roughly 1-1000 seconds after the Big Bang. A gluino that decays during or after BBN injects hadronic energy into the primordial plasma, altering the abundances of light elements — particularly deuterium and lithium-6 — that are among the most precisely predicted quantities in cosmology.
The Key Result
A TeV-mass gluino must have a lifetime shorter than roughly 100 seconds to avoid disrupting the observed light-element abundances. Since the gluino lifetime scales as the fourth power of the squark mass, this sets an upper limit on the SUSY breaking scale of about 109 GeV. Split supersymmetry remains viable, but the scalar masses cannot be arbitrarily high — BBN constrains them from above just as naturalness once constrained them from below.
Recollections
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