Quarks as a Thermometer for Cosmologies
Abstract
If physical quarks exist, their density relative to ordinary baryons (nq/flB) depends sensitively on the highest temperatures reached during cosmological evolution. Zel'dovich has pointed out that in the conventional hot big bang with a limited spectrum of elementary particles the quark density flq/flB predicted for the present time is much larger than the experimental upper bound. In the present paper we derive the consequences for conventional cosmologies of the Hagedorn type of hadron spectrum which implies a "warm" limiting temperature of order kT 160 MeV. With initial temperatures of this order, the predicted flq/flB is consistent with present experimental limits if the quark mass exceeds 9 GeV. In the Hagedorn model, quarks with rn, > 9 GeV would be very difficult to produce in accelerator experiments because of statistical competition; searches for fossil quarks in bulk matter seem to offer the only hope of detection. We also discuss predictions for the quark density in several less conventional cosmologies (mix master, Brans-Dicke, Lemaitre, steady state, and Klein-Alfven) and with forms of the hadron density of states that differ from Hagedorn's proposed form
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 1972
- DOI:
- 10.1086/151558
- Bibcode:
- 1972ApJ...175..307F