Particle glossary

*Key at the bottom
Matter particles
Particle Type Mass Interactions* Comment
matter matter - - Collective name for all particles building up the whole Universe.
antimatter antimatter - - Collective name for the antipartners to all the matter particles. For each particle there is a kind of "mirror" particle - the antiparticle - with opposite properties.
quarks matter - G,EM,S,W Collective name for the six matter particles forming the hadrons.
u quark (matter) 5 MeV G,EM,S,W Quark of the first family. Thought to be fundamental. Building block in protons and neutrons (and hadrons in general).
d quark (matter) 10 MeV G,EM,S,W Quark of the first family. Thought to be fundamental. Building block in protons and neutrons (and hadrons in general).
s quark (matter) 200 MeV G,EM,S,W Quark of the second family. Thought to be fundamental. Building block in hadrons.
c quark (matter) 1.5 GeV G,EM,S,W Quark of the second family. Thought to be fundamental. Building block in hadrons.
b quark (matter) 4.5 GeV G,EM,S,W Quark of the third family. Thought to be fundamental. Building block in hadrons.
t quark (matter) 180 GeV G,EM,S,W Quark of the third family. Thought to be fundamental. Building block in hadrons. Discovered in 1995.
antiquarks antimatter - G,EM,S,W Each of the quarks above has an antipartner building up antihadrons.
leptons matter - G,EM,W Collective name for electrons, muons, taus, and the three different neutrinos.
electron lepton (matter) 511 keV G,EM,W Thought to be fundamental. Building block in atoms
muon lepton (matter) 106 MeV G,EM,W Thought to be fundamental. Heavier relative to the electron.
tau lepton (matter) 1.8 GeV G,EM,W Thought to be fundamental. Yet heavier relative to the electron (and muon).
neutrinos lepton (matter) 0? G?, W Thought to be fundamental. Neutral sister to the electron, muon and tau. There are three kinds.
antileptons antimatter - G,EM,W Each of the leptons above has its own antipartner, such as for instance the antielectron, or positron.
positron lepton(antimatter) 511 keV G,EM,W Thought to be fundamental. The electron's antipartner.
hadrons matter - G,EM,S,W Collective name for all composite particles built up of quarks.
proton hadron (matter) 939 MeV G,EM,S,W Quark composite building up the nuclei in the atoms.
neutron hadron (matter) 940 MeV G,EM,S,W Quark composite building up the nuclei in the atoms.
antihadrons antimatter - G,EM,S,W Collective name for all composite particles built up of antiquarks.
antiproton hadron(antimatter) 939 MeV G,EM,S,W The antipartner to the proton.

Force particles
Particle Type Mass Interactions* Comment
bosons force - - Collective name for the carriers of the fundamental forces.
photon boson (force) 0 EM Carrier of the electromagnetic force. Also carrying electromagnetic radiation.
graviton? boson (force) 0 G Carrier of the gravitational force. Not yet discovered.
W boson (force) 80 GeV W,EM,G Carrier of the weak force.
Z boson (force) 91 GeV W,G Carrier of the weak force.
gluons boson (force) 0 S Carriers of the strong force. There are eight different gluons.
higgs boson (force) ? ? Postulated particle to solve the problem of the origin of mass. Carries the higgs field which should endow the massive matter particles with their masses. One of the most hot topics of particle physics reasearch today.

Key:


Particle Physics Education CD-ROM 1999 CERN