Charm

I’ve always been fascinated by the following as explained by the European Organization for Nuclear Research (CERN):

All matter around us is made of elementary particles, the building blocks of matter. These particles occur in two basic types called quarks and leptons. Each group consists of six particles, which are related in pairs, or ‘generations’. The lightest and most stable particles make up the first generation, whereas the heavier and less-stable particles belong to the second and third generations.

All stable matter in the universe is made from particles that belong to the first generation; any heavier particles quickly decay to more stable ones. The six quarks are paired in three generations – the ‘up quark’ and the ‘down quark’ form the first generation, followed by the ‘charm quark’ and ‘strange quark’, then the ‘top quark’ and ‘bottom (or beauty) quark’.

Quarks also come in three different ‘colours’ and only mix in such ways as to form colourless objects. The six leptons are similarly arranged in three generations – the “electron” and the “electron neutrino”, the “muon” and the “muon neutrino”, and the “tau” and the “tau neutrino”. The electron, the muon and the tau all have an electric charge and a sizeable mass, whereas the neutrinos are electrically neutral and have very little mass.

The best understanding of how these particles and three of the forces are related to each other is encapsulated in the Standard Model of particle physics but I’m not going down that path. Let’s stick with quarks. Why Quark?

In the early 1960s, American physicist Murray Gell-Man came up with the word quork, which he used to refer to his concept of an elementary particle smaller than a proton or neutron (by his own account he was in the habit of using names like ‘squeak’ and ‘squork’ for peculiar objects). He later settled on the spelling quark after reading a line from James Joyce’s Finnegans Wake: “Three quarks for Muster Mark!” This name was chosen because it was originally theorized that all of composite matter was built from 3 quarks.

In 1970, physicists Sheldon L. Glashow, John Iliopoulos and Luciano Maiani proposed a fourth quark, serving as a counterpart to the strange quark much like top and bottom. And so, on by what most accounts call a whim, they named it the charm quark. The first charmed particles were observed in 1974.

I have no idea what the following means:

‘It is known as the Glashow–Iliopoulos–Maiani (GIM) mechanism through which flavour-changing neutral currents (FCNCs) are suppressed in loop diagrams. It also explains why weak interactions that change strangeness by 2 (ΔS = 2 transitions) are suppressed, while those that change strangeness by 1 (ΔS = 1 transitions) are allowed, but only in charged current interactions.’

Glashow said the name was because of the “symmetry it brought to the subnuclear world”, balancing the number of known quarks and leptons. He also associated charms with warding off evil. The charm quark prevented particle decays predicted by the three-quark theory, which can look evil to a particle physicist when the timing is bad enough.

I remember starting Finnegans Wake years ago but giving up after a few pages.

from Finnegans Wake by James Joyce

Three quarks for Muster Mark!
Sure he hasn't got much of a bark
And sure any he has it's all beside the mark.
But O, Wreneagle Almighty, wouldn't un be a sky of a lark
To see that old buzzard whooping about for uns shirt in the dark
And he hunting round for uns speckled trousers around by Palmer-stown Park?
Hohohoho, moulty Mark!
You're the rummest old rooster ever flopped out of a Noah's ark
And you think you're cock of the wark.
Fowls, up! Tristy's the spry young spark
That'll tread her and wed her and bed her and red her
Without ever winking the tail of a feather
And that's how that chap's going to make his money and mark!

Thanks for reading, Terry Q.