strangeness

　 　

WordNet

1. (physics) one of the six flavors of quark

PrepTutorEJDIC

1. 奇妙;未知;不慣れ

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/05/10 04:09:06」(JST)

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This article is about a concept in particle physics. For the definition of "strangeness", see wikt:strangeness. For other uses, see Strange (disambiguation).

Flavour in particle physics

Flavour quantum numbers: Isospin: I or I3 Charm: C Strangeness: S Topness: T Bottomness: B′ Related quantum numbers: Baryon number: B Lepton number: L Weak isospin: T or T3 Electric charge: Q X-charge: X Combinations: Hypercharge: Y Y = (B + S + C + B′ + T) Y = 2 (Q − I3) Weak hypercharge: YW YW = 2 (Q − T3) X + 2YW = 5 (B − L) Flavour mixing CKM matrix PMNS matrix Flavour complementarity

In particle physics, strangeness S is a property of particles, expressed as a quantum number, for describing decay of particles in strong and electromagnetic reactions, which occur in a short period of time. The strangeness of a particle is defined as:

where n_s represents the number of strange quarks (s) and n_s represents the number of strange antiquarks (s).

The terms strange and strangeness predate the discovery of the quark, and were adopted after its discovery in order to preserve the continuity of the phrase; strangeness of anti-particles being referred to as +1, and particles as −1 as per the original definition. For all the quark flavor quantum numbers (strangeness, charm, topness and bottomness) the convention is that the flavor charge and the electric charge of a quark have the same sign. With this, any flavor carried by a charged meson has the same sign as its charge.

Strangeness conservation

Strangeness was introduced by Murray Gell-Mann and Kazuhiko Nishijima to explain the fact that certain particles, such as the kaons or certain hyperons, were created easily in particle collisions, yet decayed much more slowly than expected for their large masses and large production cross sections. Noting that collisions seemed to always produce pairs of these particles, it was postulated that a new conserved quantity, dubbed "strangeness", was preserved during their creation, but not conserved in their decay.

In our modern understanding, strangeness is conserved during the strong and the electromagnetic interactions, but not during the weak interactions. Consequently, the lightest particles containing a strange quark cannot decay by the strong interaction, and must instead decay via the much slower weak interaction. In most cases these decays change the value of the strangeness by one unit. However, this doesn't necessarily hold in second-order weak reactions, where there are mixes of K0 and K0 mesons. All in all, the amount of strangeness can change in a weak interaction reaction by +1,0 or -1 (depending on the reaction of course).

See also

• Isospin
• Charm
• Topness
• Bottomness
• Hypercharge
• Strangeness production

References

• D.J. Griffiths (1987). Introduction to Elementary Particles. John Wiley & Sons. ISBN 0-471-60386-4. 

Further reading

• Lessons in Particle Physics Luis Anchordoqui and Francis Halzen, University of Wisconsin, 18th Dec. 2009

English Journal

• A more detailed picture of the interactions between virtual screening-derived hits and the DNA G-quadruplex: NMR, molecular modelling and ITC studies.

• Trotta R, De Tito S, Lauri I, La Pietra V, Marinelli L, Cosconati S, Martino L, Conte MR, Mayol L, Novellino E, Randazzo A.SourceDipartimento di Chimica delle Sostanze Naturali, Universita degli Studi di Napoli "Federico II", via D. Montesano 49, I-80131 Napoli, Italy.
• Biochimie.Biochimie.2011 Aug;93(8):1280-7. Epub 2011 May 30.
• The growing amount of literature about G-quadruplex DNA clearly demonstrates that such a structure is no longer viewed as just a biophysical strangeness but it is instead being considered as an important target for the treatment of various human disorders such as cancers or venous thrombosis. In thi
• PMID 21658428

• How should nurses deal with patients' personal racism? Learning from practice.

• Deacon M.SourceFaculty of Health and Social Care, University of Chester, Warrington Campus, Warrington, UK. m.deacon@chester.ac.uk
• Journal of psychiatric and mental health nursing.J Psychiatr Ment Health Nurs.2011 Aug;18(6):493-500. doi: 10.1111/j.1365-2850.2011.01696.x. Epub 2011 Feb 15.
• This paper aims to promote practice development in the difficult area of managing patients' expressions of personal racism within the clinical environment. Racism is a global phenomenon and it is well documented that nurses experience racism within their routine practice. Nurses face unpleasant dile
• PMID 21749555

Japanese Journal

• Bound H Dibaryon in Flavor SU(3) Limit of Lattice QCD

• Inoue Takashi,Ishii Noriyoshi,Aoki Sinya,Doi Takumi,Hatsuda Tetsuo,Ikeda Yoichi,Murano Keiko,Nemura Hidekatsu,Sasaki Kenji,石井 理修,青木 愼也
• Physical review letters 106(16), 162002-1, 2011-04
• … The flavor-singlet H dibaryon, which has strangeness -2 and baryon number 2, is studied by the approach recently developed for the baryon-baryon interactions in lattice QCD. …
• NAID 120003133746

• 世界から見た日本 日本の土木の良い所・弱い所・不思議な所・違和感のある所

• 中田 光和
• 土木技術 66(4), 72-75, 2011-04
• NAID 40018782099

Related Links

• Strangeness - Wikipedia, the free encyclopedia

In particle physics, strangeness S is a property of particles, expressed as a quantum number, for describing decay of particles in strong and electromagnetic reactions, which occur in a short period of time. The strangeness of a particle is ...

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