Physics:Bottomness
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Flavour quantum numbers 

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In physics, bottomness (symbol B′; using a prime as plain B is used already for baryon number) or beauty is a flavour quantum number reflecting the difference between the number of bottom antiquarks (n_{b}) and the number of bottom quarks (n_{b}) that are present in a particle:
 [math]\displaystyle{ B^\prime = (n_b  n_{\bar b}) }[/math]
Bottom quarks have (by convention) a bottomness of −1 while bottom antiquarks have a bottomness of +1. The convention is that the flavour quantum number sign for the quark is the same as the sign of the electric charge (symbol Q) of that quark (in this case, Q = −^{1}⁄_{3}).
As with other flavourrelated quantum numbers, bottomness is preserved under strong and electromagnetic interactions, but not under weak interactions. For firstorder weak reactions, it holds that [math]\displaystyle{ \Delta B^\prime = \plusmn 1 }[/math].
This term is rarely used. Most physicists simply refer to "the number of bottom quarks" and "the number of bottom antiquarks".
References
 Anchordoqui, L.; Halzen, F. (2009). "Lessons in Particle Physics". arXiv:0906.1271 [physics.edph].
Original source: https://en.wikipedia.org/wiki/Bottomness.
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