ELEMENTARY
PARTICLE
SYMBOL*
MASS
MEAN LIFE,
s
MeV
me
Photon
Y
0
0
co
Neutrino
v
;
0
0
co
PTC
Electron
ee+
0,511
1
co
Muon
lc
IL+
105,66
206, 77
2,2.10-6
n+
n139,6
273,2
2,55.10-8
Pions
{
To
135,0
264,2
2.10
16
Kaons
{
K +
IC
493,8
966,3
1,23.10-8
ESC
K°
ko
498,0
974,5
10-10_10-8
Eta meson
71
548, 8
1074
2,4.10-1°
BARYONS
Proton
p
i5
938,26
1836,1
co
Neutron
n
R
939,55
1838,6
1.10-3
Lambda hyperon
A°
A°
1115,4
2182,8
2,6.10 -10
r
i1189,4
2328
0,8.104°
Sigma hyperons
/i+
1197
2342
1,6.104°
2 0
io
1192
2333
<10-14
1321
2585
1,7.104°
Xi hyperons
{ E F:o
::
1314
2572
3.10" 10
Omega hyperon
12ir
1675
3278
_leo
* Symbols on the right-hand side denote antiparticles