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 Σ+
, Σ0
, Σ−
), a charm (symbols Σ++
c, Σ+
c, Σ0
c), a bottom (symbols Σ+
b, Σ0
b, Σ−
b) or a top (symbols Σ++
t, Σ+
t, Σ0
t) 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 5×10−25 s.[1] This is about 20 times shorter than the timescale for strong interactions, and therefore it does not form hadrons.
Contents |
List [link]
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.[2][3]
[edit] JP = 1⁄2+ Sigma baryons
| Particle name | Symbol | Quark content |
Rest mass (MeV/c2) | I | JP | Q (e) | S | C | B' | T | Mean lifetime (s) | Commonly decays to |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sigma[4] | Σ+ |
uus | 1,189.37 ± 0.07 | 1 | 1⁄2+ | +1 | −1 | 0 | 0 | 0 | 8.018 ± 0.026 × 10−11 | p+ + π0 or |
| Sigma[5] | Σ0 |
uds | 1,192.642 ± 0.024 | 1 | 1⁄2+ | 0 | −1 | 0 | 0 | 0 | 7.4 ± 0.7 × 10−20 | Λ0 + γ |
| Sigma[6] | Σ− |
dds | 1,197.449 ± 0.030 | 1 | 1⁄2+ | −1 | −1 | 0 | 0 | 0 | 1.479 ± 0.011 × 10−10 | n0 + π− |
| charmed Sigma[7] | Σ++ c(2455) |
uuc | 2,454.02 ± 0.18 | 1 | 1⁄2 + | +2 | 0 | +1 | 0 | 0 | 3.0 ± 0.4 × 10−22[a] | Λ+ c + π+ |
| charmed Sigma[7] | Σ+ c(2455) |
udc | 2,452.9 ± 0.4 | 1 | 1⁄2 + | +1 | 0 | +1 | 0 | 0 | >1.4 × 10−22[a] | Λ+ c + π0 |
| charmed Sigma[7] | Σ0 c(2455) |
ddc | 2,453.76 ± 0.18 | 1 | 1⁄2 + | 0 | 0 | +1 | 0 | 0 | 3.0 ± 0.5 × 10−22[a] | Λ+ c + π− |
| bottom Sigma[8] | Σ+ b(?[b]) |
uub | 5,807.8+3.7 −3.9 |
1 | 1⁄2 + | +1 | 0 | 0 | −1 | 0 | Unknown | Λ0 b + π+ (seen) |
| bottom Sigma† | Σ0 b(?[b]) |
udb | Unknown | 1 | 1⁄2 + | 0 | 0 | 0 | −1 | 0 | Unknown | Unknown |
| bottom Sigma[8] | Σ− b(?[b]) |
ddb | 5,815.2 ± 2.7 | 1 | 1⁄2 + | −1 | 0 | 0 | −1 | 0 | Unknown | Λ0 b + π− (seen) |
| Top Sigma† | Σ++ t |
uut | — | 1 | 1⁄2 + | +2 | 0 | 0 | 0 | +1 | — | — |
| Top Sigma† | Σ+ t |
udt | — | 1 | 1⁄2 + | +1 | 0 | 0 | 0 | +1 | — | — |
| Top Sigma† | Σ0 t |
ddt | — | 1 | 1⁄2 + | 0 | 0 | 0 | 0 | +1 | — | — |
† ^ Particle currently unobserved, but predicted by the standard model.
[a] ^ PDG reports the resonance width (Γ). Here the conversion τ = ħ⁄Γ is given instead.
[b] ^ The specific values of the name has not been decided yet, but will likely be close to Σ
b(5810).
[edit] JP = 3⁄2+ Sigma baryons
| Particle name | Symbol | Quark content |
Rest mass (MeV/c2) | I | JP | Q (e) | S | C | B' | T | Mean lifetime (s) | Commonly decays to |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sigma[9] | Σ∗+ (1385) |
uus | 1,382.8 ± 0.4 | 1 | 3⁄2+ | +1 | −1 | 0 | 0 | 0 | 1.84 ± 0.04 × 10−23[c] | Λ0 + π+ or |
| Sigma[9] | Σ∗0 (1385) |
uds | 1,383.7 ± 1.0 | 1 | 3⁄2+ | 0 | −1 | 0 | 0 | 0 | 1.8 ± 0.3 × 10−23[c] | Λ0 + π0 or |
| Sigma[9] | Error no symbol defined(1385) | Error no link definedError no link definedError no link defined | 1,387.2 ± 0.5 | 1 | 3⁄2+ | −1 | −1 | 0 | 0 | 0 | 1.67 ± 0.09 × 10−23[c] | Error no link defined + Error no link defined or Error no symbol defined + Error no link defined or |
| charmed Sigma[10] | Error no symbol defined(2520) | Error no link definedError no link definedError no link defined | 2,518.4 ± 0.6 | 1 | 3⁄2 + | +2 | 0 | +1 | 0 | 0 | 4.4 ± 0.6 × 10−23[c] | Error no link defined + Error no link defined |
| charmed Sigma[10] | Error no symbol defined(2520) | Error no link definedError no link definedError no link defined | 2,517.5 ± 2.3 | 1 | 3⁄2 + | +1 | 0 | +1 | 0 | 0 | >3.9 × 10−23[c] | Error no link defined + Error no link defined |
| charmed Sigma[10] | Error no symbol defined(2520) | Error no link definedError no link definedError no link defined | 2,518.0 ± 0.5 | 1 | 3⁄2 + | 0 | 0 | +1 | 0 | 0 | 4.1 ± 0.5 × 10−23[c] | Error no link defined + Error no link defined |
| bottom Sigma† | Error no symbol defined | Error no link definedError no link definedError no link defined | Unknown | 1 | 3⁄2 + | +1 | 0 | 0 | −1 | 0 | Unknown | Unknown |
| bottom Sigma† | Error no symbol defined | Error no link definedError no link definedError no link defined | Unknown | 1 | 3⁄2 + | 0 | 0 | 0 | −1 | 0 | Unknown | Unknown |
| bottom Sigma† | Error no symbol defined | Error no link definedError no link definedError no link defined | Unknown | 1 | 3⁄2 + | −1 | 0 | 0 | −1 | 0 | Unknown | Unknown |
| Top Sigma† | Error no symbol defined | Error no link definedError no link definedError no link defined | — | 1 | 3⁄2 + | +2 | 0 | 0 | 0 | +1 | — | — |
| Top Sigma† | Error no symbol defined | Error no link definedError no link definedError no link defined | — | 1 | 3⁄2 + | +1 | 0 | 0 | 0 | +1 | — | — |
| Top Sigma† | Error no symbol defined | Error no link definedError no link definedError no link defined | — | 1 | 3⁄2 + | 0 | 0 | 0 | 0 | +1 | — | — |
† ^ Particle currently unobserved, but predicted by the standard model.
[c] ^ PDG reports the resonance width (Γ). Here the conversion τ = ħ⁄Γ is given instead.
See also [link]
- Delta baryon
- Hyperon
- Lambda baryon
- List of mesons
- List of particles
- Nucleon
- Omega baryon
- Physics portal
- Timeline of particle discoveries
- Xi baryon
References [link]
- ^ A. Quadt (2006). "Top quark physics at hadron colliders". European Physical Journal C 48 (3): 835–1000. Bibcode 2006EPJC...48..835Q. DOI:10.1140/epjc/s2006-02631-6.
- ^ C. Amsler et al. (2008): Particle summary tables - Baryons
- ^ J. G. Körner et al. (1994)
- ^ C. Amsler et al. (2008): Particle listings – Error no symbol defined
- ^ C. Amsler et al. (2008): Particle listings – Error no symbol defined
- ^ C. Amsler et al. (2008): Particle listings – Error no symbol defined
- ^ a b c C. Amsler et al. (2008): Particle listings – Error no symbol defined(2455)
- ^ a b T. Aaltonen et al. (2007a)
- ^ a b c C. Amsler et al. (2008): Particle listings – Error no symbol defined(1385)
- ^ a b c C. Amsler et al. (2008): Particle listings – Error no symbol defined(2520)
Bibliography [link]
- C. Amsler et al. (Particle Data Group) (2008). "Review of Particle Physics". Physics Letters B 667 (1): 1. Bibcode 2008PhLB..667....1P. DOI:10.1016/j.physletb.2008.07.018.
- J. G. Körner, M. Krämer, and D. Pirjol (1994). "Heavy Baryons". Progress in Particle and Nuclear Physics 33: 787–868. arXiv:hep-ph/9406359. Bibcode 1994PrPNP..33..787K. DOI:10.1016/0146-6410(94)90053-1.
- T. Aaltonen et al. (CDF Collaboration) (2007a). "First Observation of Heavy Baryons Error no symbol defined and Error no symbol defined". Physical Review Letters 99 (20): 202001. arXiv:0706.3868. Bibcode 2007PhRvL..99t2001A. DOI:10.1103/PhysRevLett.99.202001.
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Sigma Seven Co., Ltd. (株式会社シグマ・セブン Kabushiki-gaisha Shiguma Sebun) is a Japanese talent management firm representing a fair number of voice actors and entertainers. Founded on March 3, 1988, Sigma Seven is headquartered on the third floor of the Haga Building in Minato, Tokyo, Japan.
Notable voice actors
Female
Male
References
External links
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Stories of fantastical celestial apparitions have been told since antiquity, but the term "UFO" (or "UFOB") was officially created in 1953 by the United States Air Force (USAF) to serve as a catch-all for all such reports. In its initial definition, the USAF stated that a "UFOB" was "any airborne object which by performance, aerodynamic characteristics, or unusual features, does not conform to any presently known aircraft or missile type, or which cannot be positively identified as a familiar object." Accordingly, the term was initially restricted to that fraction of cases which remained unidentified after investigation, as the USAF was interested in potential national security reasons and/or "technical aspects" (see Air Force Regulation 200-2).
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History
Ufo
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Ufo 2
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UFO may also refer to:
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Computer technology
Brands, clubs, organizations
Books
Film and television
Podcasts:
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by Avskum
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by Avskum
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by Avskum
There's No Need For Crying
by: AvskumAnother atom bomb
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so fill up my glass with strong fucking rum
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