Hadron: Difference between revisions
imported>John R. Brews m (→Types: notation) |
imported>John R. Brews (colorless) |
||
| Line 2: | Line 2: | ||
{{TOC|right}} | {{TOC|right}} | ||
A '''hadron''' (pronounced ''hay-dron'', and based upon the Greek ''hadr''=strong) is a composite particle subject to the strong nuclear force. Although the defining feature is their strong force interactions, they also may be subject to weak and electromagnetic forces. | A '''hadron''' (pronounced ''hay-dron'', and based upon the Greek ''hadr''=strong) is a composite particle subject to the strong nuclear force. Although the defining feature is their strong force interactions, they also may be subject to weak and electromagnetic forces. | ||
All hadrons are ''colorless'', or ''white'', consisting of either a color/anticolor quark combination (the mesons) or a triple combination of quarks with all three quark colors: red, green and blue (the baryons).<ref name=Hassani/> Consequently, their external exertion of strong forces is limited. | |||
==Types== | ==Types== | ||
| Line 135: | Line 137: | ||
<ref name =Greiner> | <ref name =Greiner> | ||
{{cite book |title=Gauge theory of weak interactions |author=Walter Greiner, Berndt Müller |url=http://books.google.com/books?id=nObsd0V1sooC&pg=PA205 |pages=pp. 205 ''ff'' |chapter=§6.1 The world of hadrons |isbn=3540676724 |year=2000 |editions=3rd |publisher=Springer}} | {{cite book |title=Gauge theory of weak interactions |author=Walter Greiner, Berndt Müller |url=http://books.google.com/books?id=nObsd0V1sooC&pg=PA205 |pages=pp. 205 ''ff'' |chapter=§6.1 The world of hadrons |isbn=3540676724 |year=2000 |editions=3rd |publisher=Springer}} | ||
</ref> | |||
<ref name=Hassani> | |||
{{cite book |title=From Atoms to Galaxies: A Conceptual Physics Approach to Scientific Awareness |author=Sadri Hassani |publisher=CRC Press |year=2010 |isbn=143980849X |url=http://books.google.com/books?id=oypZ_a9pqdsC&pg=PA527 |pages=p. 527}} | |||
</ref> | </ref> | ||
Revision as of 13:23, 3 September 2011
A hadron (pronounced hay-dron, and based upon the Greek hadr=strong) is a composite particle subject to the strong nuclear force. Although the defining feature is their strong force interactions, they also may be subject to weak and electromagnetic forces.
All hadrons are colorless, or white, consisting of either a color/anticolor quark combination (the mesons) or a triple combination of quarks with all three quark colors: red, green and blue (the baryons).[1] Consequently, their external exertion of strong forces is limited.
Types
See also the articles Quark and Standard Model
The hadrons fall into two groups: the baryons with baryon number B=±1 and spin an odd multiple of 1/2, and mesons with B=0 and integer spin. The hadrons are classified further according to their isospin I and its component I3, and also by their strangeness S. The combination Y = B + S is called the strong hypercharge. Under strong interactions, B, I, I3, S are conserved, but conservation of S is violated by the weak force interactions.[2]
In general, hadrons are particles made up of quarks, antiquarks, and gluons. Their strong interactions are described by quantum chromodynamics.[3] The meson is a quark and an antiquark paired in various ways, the proton is made up of two up quarks and one down quark, and a neutron is made up of two down quarks and one up quark.[4][5] Some other examples appear in the tables below. Symbols u, d, s refer to up, down and strange quarks, and overlines indicate antiparticles.
| Particle name | Symbol | Quark structure | Q (e) | Baryon number B | Strangeness S | Spin | Isospin I | Mass (relative) | Lifetime (s) |
|---|---|---|---|---|---|---|---|---|---|
| Proton | p | 1 | 1 | 0 | 1/2 | 1/2 | 1 | Stable | |
| Neutron | n | 0 | 1 | 0 | 1/2 | 1/2 | 1 | 898 | |
| Lambda zero | Λ0 | 0 | 1 | -1 | 1/2 | 0 | 1.2 | 2.6 × 10-10 | |
| Omega minus | Ω− | -1 | 1 | −3 | 1/2 | 0 | 1.8 | 0.8 × 10-10 |
| Particle name | Symbol | Quark structure | Q (e) | Baryon number B | Strangeness S | Spin | Isospin I | Mass (relative) | Lifetime (s) |
|---|---|---|---|---|---|---|---|---|---|
| Pion zero | π0 | 0 | 0 | 0 | 0 | 1 | 0.14 | 0.8 × 10-16 | |
| Pion plus | π+ | 1 | 0 | 0 | 0 | 1 | 0.14 | 2.6 × 10-8 | |
| Kaon plus | K+ | 1 | 0 | 1 | 0 | 1/2 | 0.52 | 1.2 × 10-8 | |
| Kaon zero | K0 | 0 | 0 | 1 | 0 | 1/2 | 0.53 | 8.9 × 10-11 |
References
- ↑ Sadri Hassani (2010). From Atoms to Galaxies: A Conceptual Physics Approach to Scientific Awareness. CRC Press, p. 527. ISBN 143980849X.
- ↑ Walter Greiner, Berndt Müller (2000). “§6.1 The world of hadrons”, Gauge theory of weak interactions. Springer, pp. 205 ff. ISBN 3540676724.
- ↑ Leonard Susskind (2005). The cosmic landscape: string theory and the illusion of intelligent design. Hachette Digital, Inc., p. 159. ISBN 0316155799.
- ↑ Don Lincoln (2004). Understanding the universe: from quarks to the cosmos. World Scientific, p. 115. ISBN 9812387056.
- ↑ Helen R. Quinn, Yossi Nir (2010). The Mystery of the Missing Antimatter. Princeton University Press, p. 249. ISBN 1400835712.