Physics XII Notes for Physics Notes

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Hadrons, Baryons And Mesons

We got to see a word ‘hadrons, baryons, and mesons’ above. But what actually are they?

As mentioned above, hadrons are composite particles made of quarks.

Although individual quarks have fractional electrical charges, they combine such that hadrons have a net integer electric charge. Another property of hadrons is that they have no net color charge even though the quarks themselves carry color charge.
There are two classes of hadrons. They are: Baryons & Mesons.

Baryons are any hadrons which are made of three quarks (qqq).


Because they are made of two up quarks and one down quark (uud), protons are baryons. So are neutrons (udd).
Below is the table showing different baryons and their properties.


Mesons are any hadrons which contain one quark (q) and one anti-quark.


One example of a meson is a pion ( +), which is made of an up quark and a down anti-quark. The antiparticle of a meson just has its quark and anti-quark switched, so an anti-pion ( –) is made of a down quark and an up anti-quark.
Because a meson consists of a particle and an antiparticle, it is very unstable.
Below is the table showing different mesons and their properties.


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