bei48482_FM

Table 13.6Quarks and leptons and the interactions that affect them. Ordinary

matter involves only the first generation. For each quark and lepton there is an

antiquark and antilepton.

Quarks Leptons

First Up Down Electron e-neutrino

ud ee

Second Charm Strange Muon -neutrino

cs

Third ToptbBottom Tau-neutrino



Electric ^23  ^13   10

Red

Color Green Colorless

Blue

Color

Electro-

magnetic

Weak

Generation

Charge

Interaction

effect, Fig. 13.11 shows what happens when an energetic gamma-ray photon impinges

on a neutron (composition udd) and causes a uuquark-antiquark pair to come into

being. The quarks udduuthen rearrange themselves into a proton (duu) and a

negative pion (ud), so that the net reaction is

n^0 →p

Elementary Particles 493

Figure 13.11No matter how much energy is imparted to a hadron, an individual quark never emerges.

Here energy is given to a neutron by a photon, and the result is a quark-antiquark pair created inside

the neutron. The various quarks may then rearrange themselves into a proton and a negative pion.

u

n^0

dd

uu

ddu

d

p+

uu

ud

π−

γ

+

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