Abstract
It is argued that the lightest supersymmetric particle (LSP) emerging from the superstring theory is a mixture of neutral gauginos and matter fermions. Their mixing matrix is presented, calculated in a plausible minimal low-energy model abstracted from the superstring and the composition of the LSP χ is exhibited. Its relic cosmological density is computed and it is found that it lies within a factor 2 of the critical density required for closure, over a wide range of possible input parameters. Also the flux of neutrinos from LSP annihilation in the sun is computed, and it is found that it straddles the upper bound from proton decay detectors. Acceptable fluxes are obtained if mχ < mt, in which case the superstring relic can have the critical density for a present Hubble expansion rate H0 {greater-than or approximate} 50 km/s/Mpc only if mt {greater-than or approximate} 40 GeV.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 270-278 |
| Number of pages | 9 |
| Journal | Physics Letters B |
| Volume | 173 |
| Issue number | 3 |
| DOIs | |
| State | Published - Jun 12 1986 |
Bibliographical note
Funding Information:We cannot see most of the matter in the Universe, and would like to understand the nature of this dark matter. One of the most attractive hypotheses is that it is some species of stable, massive, weakly-interacting elementary particle. Just such a particle is predicted by most supersymmetric models, where the lightest supersymmetric particle (LSP) is usually stable because of R parity conservation \[1\]M. any models for the dark matter invoke mass scales which are very different from that of conventional baryonic matter \[2\]a, nd hence do not naturally predict a dark matter density PD similar to that of baryons (0B)-Since the baryon density 0B is within two orders of magnitude \[3\] of the critical density PC required for closure, this means that such models do not naturally predict a dark matter density PD similar to the closure density PC, and one must tune parameters to force PD "~ O(PC) as required by observation and by inflation. This objection need not apply to supersymmetric models \[4,5\]w, hose mass scale of order 100 GeV is not much different from that of baryons. Indeed, calculations \[6\] in the minimal supersymmetric extension of the standard model gave a lower bound PD ~ 10-2 PC and could naturally accommodate PD ~ PC- Nowadays the minimal supersymmetric standard model has been displaced in the affections of theorists by the E 8 × E~ superstring \[7\]a, nd one inevitably asks what dark matter candidates it contains, and what their relic density PD might be. The E 8 × E~ superstring contains two gauge sectors which are linked only by interactions i Permanent address: Department of Physics, University of Alberta, Edmonton, Alberta, Canada T6G 2J1. 2 Present address: Research Institute for Theoretical Physics, University of Helsinki, SF-00170 Helsinki, Finland. 3 Supported by DOE grant DE-AC02-83ER-40105.
Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.