baryon-to-photon ratio

baryon-to-photon ratio

[′bar·ē‚än tə ′fō‚tän ′rā·shō]
(astronomy)
The estimated ratio of the number of baryons (mostly protons and neutrons) to photons (mostly in the cosmic microwave radiation) in the universe.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.