New constraints on neutralino dark matter in the supersymmetric standard model

Abstract

We investigate the prospects for neutralino dark matter within the supersymmetric standard model (SSM) including the constraints from universal soft supersymmetry breaking and radiative breaking of the electroweak symmetry. The latter is enforced by using the one-loop Higgs effective potential which automatically gives the one-loop-corrected Higgs-boson masses. The radiative breaking constraint imposes novel correlations between the traditional relic density variables and makes the Higgs-boson masses variable and generally heavy throughout the allowed parameter space. We perform an exhaustive search of this five-dimensional space and find that the neutralino relic abundance ${\ensuremath{\Omega}}_{\ensuremath{\chi}}{h}_{0}^{2}$ depends most strongly on the ratio ${\ensuremath{\xi}}_{0}=\frac{{m}_{0}}{{m}_{\frac{1}{2}}}$. For ${\ensuremath{\xi}}_{0}\ensuremath{\gg}1$ the relic abundance is almost always much too large, wheras for ${\ensuremath{\xi}}_{0}\ensuremath{\ll}1$ the opposite occurs. For ${\ensuremath{\xi}}_{0}\ensuremath{\sim}1$ there are wide ranges of the remaining parameters for which ${\ensuremath{\Omega}}_{\ensuremath{\chi}}\ensuremath{\sim}1$. We also determine that ${m}_{\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{l}}\ensuremath{\gtrsim}100$ GeV is necessary in order to possibly achieve ${\ensuremath{\Omega}}_{\ensuremath{\chi}}\ensuremath{\sim}1$. Moreover, for ${m}_{{\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{t}}_{1}}\ensuremath{\gtrsim}45(100)$ GeV ${m}_{\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{q}}\ensuremath{\gtrsim}170(250)$ GeV is also required.