Delta baryon

From Wikipedia, the free encyclopedia

The Delta baryons are relatively light (1,232 MeV/c²) baryons made of only up (u) and down (d) quarks of isospin 3/2 and spin 3/2 whose ground state parity are +.

Contents 1 Decay 2 Composition 3 List of Deltas 4 See also 5 References

[edit] Decay

All varieties of Δ quickly decay via the strong force into an ordinary nucleon plus a pion, with the amplitudes of various final charge states given by their respective isospin couplings. More rarely and more slowly, the Δ⁺ can decay into a proton and a photon and the Δ⁰ can decay into neutron and a photon.

[edit] Composition

The 3/2 spin means that all the quarks inside a Δ particle have their spin axes pointing in the same direction, unlike the nearly identical proton and neutron (called "nucleons") in which the intrinsic spin of one of the three constituent quarks is always opposite the spin of the other two. This difference in spin alignment is the only quantum number distinction between the Δ⁺ and Δ⁰ and ordinary nucleons, whose spin is 1/2.

The Δ family consists of four different particles distinguished by their electrical charges, which is the sum of the charges of the mixture of up (u) and down (d) quarks which compose the Δ. There are also four antiparticles with opposite charges, made up of the corresponding antiquarks. The existence of the Δ⁺⁺, with its unusual +2 charge, was a crucial clue in the development of the quark model.

[edit] List of Deltas

Delta Baryons

Particle	Symbol	Makeup	Rest mass MeV/c²	Isospin I	Spin(Parity) JP	Q	S	C	B	Mean lifetime s	Decays to
Delta [1]	Δ++(1232)	uuu	1 232(1)	3⁄2	3⁄2+	+2	0	0	0	6×10−24 [2]	p+ + π+
Delta [1]	Δ+(1232)	uud	1 232(1)	3⁄2	3⁄2+	+1	0	0	0	6×10−24 [2]	π+ + n0 or π0 + p+
Delta [1]	Δ0(1232)	udd	1 232(1)	3⁄2	3⁄2+	0	0	0	0	6×10−24 [2]	π0 + n0 or π− + p+
Delta [1]	Δ−(1232)	ddd	1 232(1)	3⁄2	3⁄2+	−1	0	0	0	6×10−24 [2]	π− + n0

[edit] See also

• Lambda baryon
• List of particles
• Nucleon
• Omega baryon
• Particle Physics
• Physics portal
• Quark model
• Standard model
• Sigma baryon
• Timeline of particle discoveries
• Xi baryon

[edit] References

1. ^ ^{a b c d} Particle Data Groups: 2006 Review of Particle Physics - Delta (1232). Retrieved on 2008-04-20.
2. ^ ^{a b c d} Physics Particle Overview - Baryons. Retrieved on 2008-04-20.

v • d • e Particles in physics Elementary particles Fermions:  Quarks: u · d · c · s · t · b • Leptons: e− · e+ · μ− · μ+ · τ− · τ+ · νe · νμ · ντ · νe · νμ · ντ Bosons:  Gauge bosons: γ · g · W± · Z  Other:  Ghosts Composite particles Hadrons:  Baryons/Hyperons/Nucleons: p+ · n0 · Δ · Λ · Σ · Ξ · Ω • Mesons/Quarkonia: π · K · ρ · J/ψ · Υ Other:  Atomic nuclei • Atoms • Exotic atoms: Positronium · Muonium • Molecules Hypothetical elementary particles Superpartners: Axino · Chargino · Gaugino · Gluino · Gravitino · Higgsino · Neutralino · Sfermion Other: Axion · Dilaton · Graviton · Higgs boson · Tachyon · X · Y · W' · Z' · Sterile neutrino Hypothetical composite particles Exotic hadrons:  Exotic baryons: Dibaryon · Pentaquark • Exotic mesons: Glueball · Tetraquark Other:  Mesonic molecule Quasiparticles Davydov soliton · Exciton · Magnon · Phonon · Plasmon · Polariton · Polaron · Roton Lists List of particles · List of baryons · List of mesons · Timeline of particle discoveries