c) Quarks

e) simple quark model of hadrons in terms of up (u), down (d), and strange (s) quarks and their respective antiquarks

f) quark model of the proton (uud) and the neutron (udd)

d) charges of the up (u), down (d), strange (s), antiup (ubar), antidown (dbar), and the antistrange (sbar) quarks and fractions of the elementary charge

quarks

• up (u)

  • charge = 2/3

• down (d)

  • charge = -1/3

• strange (s)

  • charge = -1/3

antiquarks

• antiup (ubar)

  • charge = -2/3

• antidown (dbar)

  • charge = 1/3

• antistrange (sbar)

  • charge = 1/3

quarks in hadrons are held together by the strong nuclear force

the charge of a hadron = the sum of the charges of its quarks

protons

• consists of up, up, down (uud) quarks

neutron

• consists of up, down, down (udd) quarks

baryon = a hadron made up of three quarks

meson = a hadron made up of a quark and an antiquark