Composition .mw-parser-output .plainlist ol,.mw-parser-output .plainlist ul{line-height:inherit;list-style:none;margin:0;padding:0}.mw-parser-output .plainlist ol li,.mw-parser-output .plainlist ul li{margin-bottom:0} Δ++: uuu Δ+: uud Δ0: udd Δ−: ddd Fermionic Strong, weak, electromagnetic, and gravity Δ 4 1232±2 MeV/c2 .mw-parser-output .sfrac{white-space:nowrap}.mw-parser-output .sfrac.tion,.mw-parser-output .sfrac .tion{display:inline-block;vertical-align:-0.5em;font-size:85%;text-align:center}.mw-parser-output .sfrac .num{display:block;line-height:1em;margin:0.0em 0.1em;border-bottom:1px solid}.mw-parser-output .sfrac .den{display:block;line-height:1em;margin:0.1em 0.1em}.mw-parser-output .sr-only{border:0;clip:rect(0,0,0,0);clip-path:polygon(0px 0px,0px 0px,0px 0px);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px}⁠ 3 /2⁠, ⁠ 5 /2⁠, ⁠ 7 /2⁠ ... 0 0 0 0 ⁠ 3 /2⁠

The Delta baryons (or Δ baryons, also called Delta resonances) are a family of subatomic particle made of three up or down quarks (u or d quarks), the same constituent quarks that make up the more familiar protons and neutrons.

## Properties

Four closely related Δ baryons exist:
Δ++
(constituent quarks: uuu),
Δ+
(uud),
Δ0
(udd), and
Δ
(ddd), which respectively carry an electric charge of +2 e, +1 e, e, and −1 e.

The Δ baryons have a mass of about 1232 MeV/c2; their third component of isospin ${\displaystyle \;I_{3}=\pm {\tfrac {1}{2))~{\mathsf {or))~\pm {\tfrac {3}{2))\;;}$ and they are required to have an intrinsic spin of  3 /2 or higher (half-integer units). Ordinary nucleons (symbol N, meaning either a proton or neutron), by contrast, have a mass of about 939 MeV/c2, and both intrinsic spin and isospin of 1/ 2 . The
Δ+
(uud) and
Δ0
(udd) particles are higher-mass spin-excitations of the proton (
N+
, uud) and neutron (
N0
, udd), respectively.

The
Δ++
and
Δ
, however, have no direct nucleon analogues: For example, even though their charges are identical and their masses are similar, the
Δ
(ddd), is not closely related to the antiproton (
p
uud).

The Delta states discussed here are only the lowest-mass quantum excitations of the proton and neutron. At higher spins, additional higher mass Delta states appear, all defined by having constant  3 /2 or  1 /2 isospin (depending on charge), but with spin  3 /2,  5 /2,  7 /2, ...,  11 /2 multiplied by ħ. A complete listing of all properties of all these states can be found in Beringer et al. (2013).[1]

There also exist antiparticle Delta states with opposite charges, made up of the corresponding antiquarks.

## Discovery

The states were established experimentally at the University of Chicago cyclotron[2][3] and the Carnegie Institute of Technology synchro-cyclotron[4] in the mid-1950s using accelerated positive pions on hydrogen targets. The existence of the
Δ++
, with its unusual electric charge of +2 e, was a crucial clue in the development of the quark model.

## Formation and decay

The Delta states are created when a sufficiently energetic probe – such as a photon, electron, neutrino, or pion – impinges upon a proton or neutron, or possibly by the collision of a sufficiently energetic nucleon pair.

All of the Δ baryons with mass near 1232 MeV quickly decay via the strong interaction into a nucleon (proton or neutron) and a pion of appropriate charge. The relative probabilities of allowed final charge states are given by their respective isospin couplings. More rarely, the
Δ+
can decay into a proton and a photon and the
Δ0
can decay into a neutron and a photon.

## List

Delta baryons
Particle
name
Symbol Quark
content
Mass
(MeV/c2)
I3 JP Q
(e)
S C B′ T Mean lifetime
(s)
Commonly
decays to
Delta[1]
Δ++
(1 232)

u

u

u
1232±2 + 3 /2  3 /2+ +2 0 0 0 0 (5.63±0.14)×10−24[a]
p+
+
π+
Delta[1]
Δ+
(1 232)

u

u

d
1232±2 +1/ 2   3 /2+ +1 0 0 0 0 (5.63±0.14)×10−24[a]
π+
+
n0
, or

π0
+
p+
Delta[1]
Δ0
(1 232)

u

d

d
1232±2 ⁠−+1/ 2   3 /2+ 0 0 0 0 0 (5.63±0.14)×10−24[a]
π0
+
n0
, or

π
+
p+
Delta[1]
Δ
(1 232)

d

d

d
1232±2 ⁠−+ 3 /2  3 /2+ −1 0 0 0 0 (5.63±0.14)×10−24[a]
π
+
n0

[a] ^ PDG reports the resonance width (Γ). Here the conversion ${\textstyle \tau ={\frac {\hbar }{\Gamma ))}$ is given instead.

## References

1. Beringer, J.; et al. (Particle Data Group) (2013).
Δ
(1 232)
(PDF) (Report). Particle listings.
2. ^ Anderson, H. L.; Fermi, E.; Long, E. A.; Nagle, D. E. (1 March 1952). "Total cross-sections of positive pions in hydrogen". Physical Review. 85 (5): 936. Bibcode:1952PhRv...85..936A. doi:10.1103/PhysRev.85.936.
3. ^ Hahn, T. M.; Snyder, C. W.; Willard, H. B.; Bair, J. K.; Klema, E. D.; Kington, J. D.; Green, F. P. (1 March 1952). "Neutrons and gamma-rays from the proton bombardment of beryllium". Physical Review. 85 (5): 934. Bibcode:1952PhRv...85..934H. doi:10.1103/PhysRev.85.934.
4. ^ Ashkin, J.; Blaser, J. P.; Feiner, F.; Stern, M. O. (1 February 1956). "Pion-proton scattering at 150 and 170 Mev". Physical Review. 101 (3): 1149–1158. Bibcode:1956PhRv..101.1149A. doi:10.1103/PhysRev.101.1149. hdl:2027/mdp.39015095214600.