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Sigma baryon
The Sigma baryons are a family of subatomic hadron particles which have a +2, +1 or −1 elementary charge or are neutral. They are baryons containing three quarks: two up and/or down quarks, and one third quark, which can be either a strange (symbols , , ), a charm (symbols , , ), a bottom (symbols , , ) or a top (symbols , , ) quark. However, the top Sigmas are not expected to be observed as the Standard Model predicts the mean lifetime of top quarks to be roughly .〔
〕 This is about 20 times shorter than the timescale for strong interactions, and therefore it does not form hadrons.
==List==
The symbols encountered in these lists are: I (''isospin''), J (''total angular momentum''), P (''parity''), u (''up quark''), d (''down quark''), s (''strange quark''), c (''charm quark''), t (''top quark''), b (''bottom quark''), Q (''charge''), B (''baryon number''), S (''strangeness''), C (''charmness''), B′ (''bottomness''), T (''topness''), as well as other subatomic particles (hover for name).
Antiparticles are not listed in the table; however, they simply would have all quarks changed to antiquarks, and Q, B, S, C, B′, T, would be of opposite signs. I, J, and P values in red have not been firmly established by experiments, but are predicted by the quark model and are consistent with the measurements.〔C. Amsler et al. (2008): (Particle summary tables – Baryons )〕〔J. G. Körner et al. (1994)〕
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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