If we look inside the proton or neutron we find that they are not elementary particales but are made up of smaller particles. In fact, the existence of quarks was proposed as a way to construct all the known hadrons from smaller particles. The model has since been extended and refined, and now there are six types of quark, together with their antiquarks. The quarks have properties of mass, charge, baryon number and strangeness.
Baryons are made up of three quarks and mesons are made up of two. A particle's net charge, baryon number, strangeness etc are equal to the sum of those quantities for the quarks that make up the particle.
|
Symbol |
Charge/e |
Baryon Number |
Strangeness |
Charm |
|
|
Up |
u |
|
|
0 |
0 |
|
Down |
d |
|
|
0 |
0 |
|
Strange |
s |
|
|
-1 |
0 |
|
Charm |
c |
|
|
0 |
1 |
|
Top (Truth) |
t |
|
|
0 |
0 |
|
Bottom (Beauty) |
b |
|
|
0 |
0 |
Quark Composition of Several Hadrons
|
|
|
|
|
|
|
p |
|
|
|
|
