An elementary particle is a particle with no measurable internal structure, that is, it is not a composite of other particles. Elementary particles can be classified according to their spin.

Fermions have half-integral spin; for all known elementary particles this is 1/2. Each fermion has its own distinct antiparticle. Fermions are the basic building blocks of all matter. They are classified according to whether they interact via the color force or not.
- According to the Standard Model there are 12 flavors of elementary fermions, six quarks and six leptons.
  - Quarks can interact via the color force. They exist in six flavors: down, up, strange, charm, bottom and top.
  - Leptons do not interact via the color force. They also exist in six flavors: electron, muon, tauon, electron-neutrino, muon-neutrino and tauon-neutrino.
- Supersymmetric theories predict the existence of more fermions. Their existence has not been confirmed experimentally.
  - The neutralino (spin 1/2) is a superposition of the superpartners of several neutral standard model particles. It is a leading candidate for dark matter. The partners of charged bosons are called charginos.
  - The photino (spin 1/2) is the superpartner of the photon.
  - The gravitino (spin 3/2) is the superpartner of the graviton boson in supergravity theories.
Bosons have integral spin. The fundamental forces of nature are mediated by gauge bosons.
- According to the Standard Model there are 13 elementary bosons.
  - The photon (spin 1) mediates the electromagnetic force.
  - The W+, W- and Z0 bosons (spin 1) mediate the weak nuclear force.
  - The eight gluons (spin 1) mediate the strong nuclear force.
  - The Higgs boson (spin 0) is predicted by standard model electroweak theory. Physicists expect the Higgs to be discovered at the Large Hadron Collider (LHC) particle accelerator now under construction at CERN
- New theories predict the existence of other bosons.
  - The graviton (spin 2) has been proposed to mediate gravity in a theory of quantum gravity.
  - The supersymmetric partners of the standard model fermions (sleptons and squarks) would also be bosons.

Quarks (spin = 1/2):

Flavor	Mass (GeV)	Electric Charge
Up: u	0.003	2/3
Down: d	0.006	-1/3
Charm: c	1.3	2/3
Strange: s	0.1	-1/3
Top: t	175	2/3
Bottom: b	4.3	-1/3

Leptons (spin = 1/2):

Particle	Symbol	Anti- particle	Rest mass MeV/c^2	L(e)	L(muon)	L(tau)	Lifetime (seconds)
Electron	e^-	e⁺ positron	0.511	+1	0	0	Stable
Neutrino (Electron)	ν_e	ν_e	0(<7 x 10^-6)	+1	0	0	Stable
Muon decay modes	µ^-	µ⁺	105.7	0	+1	0	2.20x10^-6
Neutrino (Muon)	ν_µ	ν_µ	0(<0.27)	0	+1	0	Stable
Tau (decay modes see lbl.gov)	τ^-	τ⁺	1777	0	0	+1	2.96x10^-13
Neutrino (Tau)	ν_τ	ν_τ	0(<31)	0	0	+1	Stable

Bosons:

Particle	Symbol	Charge	Spin	Rest mass MeV/c^2	Lifetime (seconds)	Primary Decay Mode(s)
photon	γ	0	1	0	-	-
gluon	g	0	1	0	-	-
W	W⁺	1	1	80000	3.2x10^-25	hadrons(67.96), [e⁺,µ⁺,τ⁺]ν(~10 each), etc.
W	W^-	-1	1	80000	3.2x10^-25	charge conjugates of W⁺
Z	Z	0	1	91000	2.6x10^-25	hadrons(69.91), invisible to detectors(20), [e⁺,µ⁺,τ⁺]ν(~3.37 each)
Higgs	H⁺	1	0	large	?	not observed
Higgs	H^-	-1	0	large	?	not observed
Higgs	H⁰	0	0	large	?	not observed
Axion	A⁰					not observed

Composite particles

Molecules
Atoms
Atomic nuclei
Hadrons are defined as strongly interacting composite particles. Hadrons are either bosons (named: mesons), or fermions (named: baryons)
- Ordinary baryons contain three valence quarks or three valence antiquarks each.
  - Nucleons are the proton and the neutron, the fermionic constituents of normal atomic nuclei.
  - Hyperons such as the Δ, Λ, Ξ and Ω particles are generally short-lived and heavier than nucleons. They do not normally appear in atomic nuclei.
- Ordinary mesons contain a valence quark and a valence antiquark, and include the pions, the kaons and many other types of mesons. In quantum hadrodynamic models the strong force between nucleons is mediated by mesons.
- Exotic baryons have been discovered only recently.
  - Pentaquarks consist of four valence quarks and one valence antiquark.
- Exotic mesons are predicted by new theories.
  - Tetraquarks consist of two valence quarks and two valence antiquarks.
  - Glueballs are bound states of two or more real gluons.
  - Hybrid s consist of one or more valence quark-antiquark pairs and one or more real gluons.

S ... strangeness
C ... charm

Baryons:

Particle	Symbol	Anti- particle	Makeup	Rest mass MeV/c^2	Spin	Lifetime (seconds)	Decay Modes / %
Proton	p	p^- and p	uud	938.3	1/2	Stable	...
Neutron	n	Self	ddu	939.6	1/2	920	pe^-ν_e(~100), pe^-ν_eγ(<6.9*10^-3)
Sigma	Σ⁺		uus	1189.4	1/2	0.8x10^-10	pπ⁰(51.64), nπ⁺(48.36), pγ(1.2310^-5), nπ⁺γ(4.510^-6), Λe⁺ν_e(2*10^-7)
Sigma	Σ⁰		uds	1192.5	1/2	6x10^-20	Λ⁰γ(~100), Λ⁰γγ(<3)
Sigma	Σ^-		dds	1197.3	1/2	1.5x10^-10	nπ^-(99.85), nπ^-γ(4.610^-6), ne^-ν_e(10^-5), nµ^-ν_µ(4.510^-6), Λe^-ν_e(5.73*10^-7)
Delta	Δ⁺⁺		uuu	1232	3/2	0.6x10^-23	pπ⁺(100)
Delta	Δ⁺		uud	1232	3/2	0.6x10^-23	pπ⁰(66.6), nπ⁺(33.3)
Delta	Δ⁰		udd	1232	3/2	0.6x10^-23	nπ⁰(66.6), pπ^-(33.3)
Delta	Δ^-		ddd	1232	3/2	0.6x10^-23	nπ^-(100)
Xi Cascade	Ξ⁰		uss	1315	1/2	2.9x10^-10	Λπ⁰(99.52), Λγ(1.1810^-5), Σ⁰γ(3.3310^-5), Σ⁺e^-ν_e(2.710^-6), Σ⁺µ^-ν_µ(<1.110^-5)
Xi Cascade	Ξ^-		dss	1321	1/2	1.64x10^-10	Λπ^-(99.98), Σ^-γ(1.2710^-6), Λe^-ν_e(5.6310^-6), Λµ^-ν_µ(3.510^-6), Σ⁰e^-ν_e(8.710^-7), Σ⁰µ^-ν_µ(<810^-6), Ξ⁰e^-ν_e(<2.310^-5)
Xi	Ξ⁺_c			2466.3		4.4x10^-13	see lbl.gov
Xi	Ξ⁰_c			2471.8		1.1x10^-13	ΛΚ⁰(seen), ΛΚ⁰π⁺π^-(seen), ΛΚ^-π⁺π^-(seen), Ξ^-π⁺(seen), Ω^-Κ⁺(seen), etc.
Xi	Ξ^'+_c			2574.1			Ξ⁺_cγ(seen)
Xi	Ξ^'0_c			2578.8			Ξ⁰_cγ(seen)
Xi	Ξ_b					1.39x10^-12	Ξ^-l^-ν_l+ (seen) (l=lepton)
Omega	Ω⁰_c			2697.5		6.9x10^-14	Σ⁺Κ^-Κ^-π⁺(seen), Ξ⁰Κ^-π⁺(seen), Ξ^-Κ^-π⁺π⁺(seen), Ω^-e⁺ν_e(seen), Ω^-π⁺(seen), Ω^-π⁺π⁰(seen), Ω^-π^-π⁺π⁺(seen)
Omega	Ω^-		sss	1672	3/2	0.82x10^-10	ΛΚ^-(67.8), Ξ⁰π^-(23.6), Ξ^-π⁰(8.6), Ξ^-π⁺π^-(4.310^-6), Ξ(1530)⁰π^-(6.410^-6), Ξ⁰e^-ν_e(5.610^-5), Ξ^-γ(<4.610^-6)
Lambda	Λ⁺_c		udc	2281	1/2	2x10^-13	pπ^-(64.2), nπ⁰(35.8)
Lambda	Λ		uds	1115.6	1/2	2.6x10^-10	pπ^-(63.9), nπ⁰(35.8), nγ(1.7510^-5), pπ^-γ(8.410^-6), pe^-ν_e(8.3210^-6), pµ^-ν_µ(1.5710^-6)
Lambda	Λ⁰_b			5624		1.23x10^-12	J/ψ(1S)Λ(4.7*10^-6), pD⁰π^-(), Λ⁺_cπ^-(seen), etc.
Theta	Θ(1540)⁺			1539.2			ΚN(100)
Phi	Φ(1860)			1862

Mesons:

Particle	Symbol	Anti- particle	Makeup of the particle	Spin	Rest mass MeV/c^2	Lifetime	Decay Modes / %
Pion	π⁺	π^-	ud	0	139.6	2.60x10^-8	decay modes
Pion	π⁰	Self	(uu+dd)/(2^1/2)	0	135.0	0.83x10^-16	decay modes
Kaon	Κ⁺	Κ^-	us	0	493.7	1.24x10^-8	µ⁺ν_µ(63.5), π⁺π⁰(21.2), π⁺π⁺π^-(5.6), π⁰e⁺ν_e(4.8), π⁰µ⁺ν_µ(3.2), π⁰π⁰π⁺(1.7), etc.
Kaon	Κ⁰_S	Κ⁰_S	1*		497.7	0.89x10^-10	π⁺π^-(68.6), 2π⁰(31.4), etc.
Kaon	Κ⁰_L	Κ⁰_L	1*		497.7	5.2x10^-8	π^±e⁺ν_e(38.81), π^±µ⁺ν_µ(27.19), 3π⁰(21.05), π⁺π^-π⁰(12.59), etc.
Kaon	Κ^*+	Κ^*-					Κ⁺π⁰(66.6), Κ⁰_Lπ⁺(16.6), Κ⁰_Sπ⁺(16.6)
Kaon	Κ^*0	Κ^*0					Κ⁺π^-(66.6), Κ⁰_Lπ⁰(16.6), Κ⁰_Sπ⁰(16.6)
Eta	η⁰	Self	(uu+dd-2ss)/(6^1/2)	0	548.8	<10^-18	2γ(39.13), 3π⁰(32.09), π⁺π^-π⁰(23.84), π⁺π^-γ(4.94)
Eta prime	η^0'	Self	(uu+dd-2ss)/(6^1/2)	0	958
Eta	η_c(1S)			0	2979.6		ΚΚπ(5.7), ηππ(4.9), etc.
Rho	ρ⁺	ρ^-	ud	1	770	0.4 x10^-23	π⁺π⁰(~100), etc.
Rho	ρ⁰	Self	uu, dd	1	770		π⁺π^-(~100), etc.
Omega	ω⁰	Self	uu, dd	1	782		π⁺π^-π⁰(89.1), π⁰γ(8.92), π⁺π^-(1.70), etc.
Phi	φ	Self	ss	1	1020	20 x10^-23	Κ⁺Κ^-(49.1), Κ⁰_LΚ⁰_S(34.0), ρπ + π⁺π^-π⁰(15.4), ηγ(1.30), etc.
D	D⁺	D^-	cd	0	1869.4	10.6x10^-13	Κ⁰+ + Κ⁰+ (61), Κ^-+ (27.5), e⁺+ (17.2), Κ⁺+ (5.5), η+ (<13), φ+ (1.8), etc.
D	D⁰	D⁰	cu	0	1864.6	4.2x10^-13	Κ^-+ (53), Κ⁰+ + Κ⁰+ (42), e⁺+ (6.87), µ⁺+ (6.5), Κ⁺+ (3.4), η+ (<13), φ+ (1.7), etc.
D	D⁺_S	D^-_S	cs	0	1969	4.7x10^-13	Κ+
D	D^*+	D^*-			2010.0		D⁰π⁺(67.7), D⁺π⁰(30.7), D⁺γ(1.6)
D	D^*0	Self			2006.7		D⁰π⁰(61.9), D⁰γ(38.1)
J/Psi	J/ψ	Self	cc	1	3096.9	0.8x10^-20	hadrons(87.7), virtualγ->hadrons(17), e⁺e^-(5.93), ν⁺ν^-(5.88), etc.
B	B⁺	B^-	bu	0	5279	1.5x10^-12	D⁺+ , etc.
B	B⁰	B⁰	db	0	5279	1.5x10^-12	K⁺+ (78), etc.
B	B_s⁰	B_s⁰	sb	0	5375		Bγ(dominant)
B	B^*			0	5325		Bγ(dominant)
B	B^*_s			0	6416.6		B_sγ(dominant)
B	B⁺_c	B^-_c		0	6400	0.46x10^-12	J/ψ(1S)l⁺ν_lanything, etc.
Upsilon	Υ	Self	bb	1	9460.4	1.3x10^-20	τ⁺τ^-(2.67), µ⁺µ^-(2.48), e⁺e^-(2.38), etc.
Chi	χ
Psi	ψ
X	X(3872)				3872		e⁺e^-, π⁺π^-J/ψ(1S)(seen), γχ_c1

1* ... These mesons are made of symetric and antisymmetric combinations of ds and ds quarks.
The makeup of the anti-particle is inverse to the makeup of the particle i.e. ud -> ud

Decay modes for anti-particles: If a particle (i.e. Kaon: Κ⁺) has an anti-particle (Κ^-), the anti-particle decays into anti-particles aswell: µ⁺ν_µ => µ^-ν_µ

Some particles have many decay modes, too many to list all in this page. Particles with partially listed decay modes have a "etc." added. PDF and postscript documents with the complete information are here: http://pdg.lbl.gov/2004/listings/contents_listings.html

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Last-Modified: Fri, 26 Aug 2005 19:06:02 GMT

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Elementary particles