What is a quark?
Definition: Any of a number of
subatomic particles carrying a fractional electric charge, postulated as
building blocks of the hadrons.
So quarks are a fundamental constituent of matter.
There are six types or flavours of quarks, up, down, strange, charm, top and
bottom. Each flavour has a corresponding anti flavour called an anti quark. For
example the up quark, symbol u, has a corresponding anti quark called anti-up,
symbol ū.
The “up” and “down” quarks are the most common flavour of quarks
because they are the most stable flavour.
As the other quarks, strange, charm top and bottom get heavier they turn
into the up and down quarks through a process called “particle decay” which is
the transformation from “a higher mass state to a lower mass state”. Strange,
charm, top and bottom can only be produced in particle accelerators (such as
CERN’s large hadron collider) or in cosmic rays. All quarks have certain
properties such as colour, electric charge, mass and spin. These different
characteristics determine which quark is which.
So what do quarks do?
You have three quarks in every baryon (The most
“familiar” baryons and they ones I will be referring to are neutrons and protons).
In a neutron for example you are likely to have one up quark and two down
quarks. The up quark has a charge of positive two thirds whilst the down quark
has a charge of negative one third. So by having two down quarks and one up
quark you have a charge of negative two thirds (-1/3 plus -1/3) and positive two
thirds. That means the charges cancel and the neutron will be neutral (this is
of course different for particles that have a charge). The principle is exactly the same for other baryons including the proton. The proton has two up quarks and one down quark, their charges cancel to create a total charge of positive one (which we all know from year 9 science is the charge on a proton). This is exactly the same for anti-quarks. If
you have three anti-quarks in the same formation as normal quarks then you have
an anti-baryon.
Attraction between quarks
Within all subatomic particles there needs to be a strong
interaction between the subatomic particles. With all quarks this is done
through their colour change property. In
a Baryon such as the neutron we were talking about earlier there are three
colours, red, blue and green. Each quark has a colour and its anti-quark and as
you may have noticed they are the primary colours so they effectively make the
neutron white. The quarks are constantly changing around colours, this allows
them have a strong interaction and really this property “bonds” everything
together. Once again this is exactly the same with anti-quarks.
You may have noticed the name of our blog is Strange Charm, which
you guessed it, are the two quarks. Besides strange and charm being my two
favourite quarks, we felt that we resembled those two quarks. Julia gets
strange…because she is strange (not saying I’m not strange, just she is more
so) and I get Charm because of a long running inside joke.
I hope you have found this explanation of quarks easy to follow
and informative. If you have any further questions or have noticed that I have
mislead or got it wrong, then please don’t hesitate to correct me in comments.
I have only covered quarks and Baryons in this post. I shall cover Leptons and
mesons in a later post. DFTBA.
For further information see YouTube, Wikipedia or Google "what is a quark".And to listen to an awesome song written and sung by Hank Green go to: http://www.youtube.com/watch?v=U0kXkWXSXRA
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