bottomnessn.
/ˈbɒtəmnəs/, U.S. /ˈbɑdəmnəs/ Particle Physics.
The characteristic flavour (flavour n. 5) of bottom quarks and bottom antiquarks that distinguishes them from other particles. Also: a quantum number expressing the value of this flavour for a quark or a particle composed of quarks. Cf. bottom n. 29.
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bottom1975
beauty1977
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bottomness1979
1979 Science 18 May 720/1 In the upsilon [family of elementary particles], there is no net bottomness because this property in one quark is canceled by the negative value of the property in the anti-quark.
1979 E. G. Floratos et al. in Nucl. Physics B. 155 147 A number of interesting predictions for charged states with new flavor quantum numbers (topness and bottomness) could also be obtained.
1992 P. A. Tipler Elem. Mod. Physics viii. 276 In addition to the usual particle properties of mass, charge, and spin, new properties have been found and given whimsical names such as strangeness, charm, color, topness, and bottomness.
2005 R. A. Serway et al. Mod. Physics (ed. 3) xv. 576 To distinguish these quarks from the old ones, quantum numbers called topness and bottomness (with allowed values +1, 0, -1) were assigned to all quarks and antiquarks.
This is a new entry (OED Third Edition, September 2016; most recently modified version published online December 2021).
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n.1979