Unitarity limits on the mass and radius of dark-matter particles
Using partial-wave unitarity and the observed density of the Universe, we show that a stable elementary particle which was once in thermal equilibrium cannot have a mass greater than 340 TeV. An extended object which was once in thermal equilibrium cannot have a radius less than 7.5×10-7 fm. A lower limit to the relic abundance of such particles is also found.
Additional Information© 1990 The American Physical Society. Received 5 October 1989. We acknowledge helpful conversations with Michael Chanowitz, Rahim Esmailzadeh, Michael Turner, and Scott Willenbrock. A special acknowledgment is due to David Seckel, who originially suggested this line of research. Similar claims of a limit on the mass of dark-matter particles have been made by David Eichler and Lawrence Hall, though not based on unitarity. This work was supported in part by the DOE (at Chicago), NASA(Grant No. NGW-1340) and the DOE (at Fermilab), and by the Office of Science and Technology Centers of the NSF, under cooperative agreement AST-8809616 (at Berkeley). M.P.K. would like to thank NASA for technical assistance.
Published - GRIprl90.pdf