Quark or lepton?

Which list gives only quark flavors?

You now know eight fundamental matter particles by name: the six quark flavors, the electron, and the neutrino. Eight names make two families, and one question sorts every name.

You've already seen the rule for the second family: the fundamental matter particles that are not quarks are the leptons. So the sort needs only the flavor list.

The sorting question is: is the particle one of the six quark flavors, up, down, charm, strange, top, or bottom? On the list, the particle is a quark. Not on the list, the particle is a lepton.

Try strange. Strange is on the flavor list, so strange is a quark. Now try the electron. The electron is not on the flavor list, so the electron is a lepton.

A particle on the flavor list is a quark. A particle not on the list is a lepton.

Sort charm: is it a quark or a lepton?

Check the flavor list: up, down, charm, strange, top, bottom.

Charm is on the list.

Charm is a quark.

Quick-fire drill

Here are six quick sorts. Ask the one question each time: is the particle on the six-flavor list?

A particle is named top. Is it a quark or a lepton?

Is the neutrino a quark or a lepton?

A particle is named down. Is it a quark or a lepton?

A particle is named bottom. Is it a quark or a lepton?

A particle is named up. Is it a quark or a lepton?

A particle has no charge and almost no mass. Is it a quark or a lepton?

Your turn

Which of the following particles is a lepton?

Which list contains only quarks?

A reference table lists the particles bottom and neutrino. Which classification of the pair is correct?