What is Flavor?
Consider these three substances:
Hydrogen Deuterium Tritium
A chemist would say "Each of these has one electron and
one proton, so each behaves the same chemically, they just have
different masses. I would call these 'isotopes' of hydrogen"
A nuclear physicist would elaborate by saying
"Looking inside the nucleus, we see that each of these
substances has a different number of neutrons."
A particle physicist, looking at the sub-nuclear
level, finds different quarks with similar properties but different
masses. As a chemist or nuclear physicist refer to atoms of
different mass and similar properties as 'isotopes', the particle
physicist uses the term 'flavor' to describe these different
quarks.
up charm top
down strange bottom
Just as the nuclear physicist explained the mass
differences of the isotopes by looking at the constituents of
the nucleus, the natural question for the particle physicist
is "Are quarks composites of yet smaller constituents?"
The same question applies to the six flavors of leptons.
We have not yet seen any evidence for such compositeness,
but ATLAS will be able to delve much deeper into quarks. The
ATLAS experiment could answer this question.
|
