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In physics, bottomness (symbol ''B''′) also called beauty, is a flavour quantum number reflecting the difference between the number of bottom antiquarks (''n'') and the number of bottom quarks (''n'') that are present in a particle: : 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 = −). As with other flavour-related quantum numbers, bottomness is preserved under strong and electromagnetic interactions, but not under weak interactions. For first-order weak reactions, it holds that . This term is rarely used. Most physicists simply refer to "the number of bottom quarks" and "the number of bottom antiquarks". ==Further reading== * de:Flavour#Quark-Flavours 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「bottomness」の詳細全文を読む スポンサード リンク
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