baryon number

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A quantum number equal to the difference between the number of baryons and the number of antibaryons in a system of subatomic particles. The baryon number remains the same throughout any reaction and is one-third of the quark number.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun physics A quantum number related to the difference between the numbers of quarks and antiquarks in a system of subatomic particles

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a number equal to the difference between the number of baryons and the number of antibaryons in any subatomic structure; it is conserved in all types of particle interactions