field guide to subatomic particles

7/31/2019 Field Guide to Subatomic Particles

1/4

The Ultimate Field Guide to Subatomic Particles:Elementary Particles Cheat Sheet

Quarks:

Up Quark :

Mass: 2.4 MeV

Charge: +2/3

Spin: 1/2

Status: Predicted in 1964 by Murray Gell-

Mann and George Zweig, discovered in 1969

at SLAC National Accelerator Laboratory

Antiparticle: Antiproton containing two up

antiquarks theorized in 1933 by Paul Dirac,

discovered in 1955 by Emilio Segr and

Owen Chamberlain

Down Quar k :

Mass: 4.8 MeV

Charge: -1/3

Spin: 1/2

Status: Predicted in 1964 by Murray Gell-

Mann and George Zweig, discovered in 1969

at SLACAntiparticle: Antiproton containing down

antiquark theorized in 1933 by Paul Dirac,

discovered in 1955 by Emilio Segr and

Owen Chamberlain

Charm Quar k:

Mass: 1.27 GeV

Charge: +2/3

Spin: 1/2

Status: Predicted in 1964 by James Bjorken and Sheldon Lee Glashow, existence demonstrated

by discovery ofJ/ meson in 1974 by Burton Richter and Samuel Ting

Str ange Quark :

Mass: 104 MeV

Charge: -1/3


2/4


3/4

M uon Neut r i no :

Mass: Less than 0.17 MeV

Charge: 0

Spin: 1/2

Status: Shown to be distinct from electron neutrino in 1962 by Leon Lederman

Tau:

Mass: 1.777 GeV

Charge: -1

Spin: 1/2

Lifetime: 2.9 * 10^-13 seconds

Status: Discovered in 1975 by Martin Perl

Tau Neutr in o:

Mass: Less than 15.5 MeV

Charge: 0Spin: 1/2

Status: Observed indirectly in 2000 at Fermilab

Bosons

Photon:

Mass: 0

Charge: 0

Spin: 1

Carries: Electromagnetic forceStatus: Discovered in 1895 by Wilhelm Rntgen in the form of X-ray photons

Gluon:

Mass: 0

Charge: 0

Spin: 1

Carries: Strong nuclear force

Status: Observed indirectly in 1979 at DESY, the German Electron Synchrotron

Z Boson:Mass: 91.2 GeV

Charge: 0

Spin: 1

Lifetime: 10^-25 seconds

Carries: Weak nuclear force

Status: Predicted by Sheldon Glashow, Abdus Salam, and Steven Weinberg, discovered in 1983


4/4

by Carlo Rubbia, Simon van der Meer, and CERN, the European Organization for Nuclear

Research

W Boson:

Mass: 80.4 GeV

Charge: Either +1 or -1

Spin: 1

Lifetime: 10^-25 seconds

Carries: Weak nuclear force

Status: Predicted by Sheldon Glashow, Abdus Salam, and Steven Weinberg, discovered in 1983

by Carlo Rubbia, Simon van der Meer, and CERN

And the two most important composite particles:

Proton:

Components: Two up quarks and one down quark

Mass: 938.272 MeV

Charge: 1 (2/3 + 2/3 - 1/3)

Spin: 1/2

Lifetime: Greater than 2.1 * 10^29 years

Status: Discovered in 1919 by Ernest Rutherford

Neutron:

Components: One up quark and two down quarks

Mass: 939.565 MeV

Charge: 0 (2/3 - 1/3 - 1/3)Spin: 1/2

Lifetime: 885.7 seconds

Status: Theorized in 1920 by Ernest Rutherford, discovered in 1932 by James Chadwick

Notes:

All antiparticles have opposite charge and identical mass, spin, and lifetime. Specific

antiparticles only listed when their discoveries were significant to development of Standard

Model.

All masses are given in electron volts.

Quarks do not have lifetimes listed because they are always found combined in nature. The

neutrino and gluon lifetimes are not currently well understood. The photon is stable and does

not decay.

field guide to subatomic particles

Documents