Quarks colour and quarks confinement.

Quarks colour

The problem associated with the idea that baryons are composed of quarks is that two or three same type of quarks are contain in a particular particle for example two u quarks in proton and three s quarks in 𝝮⁻ baryons violates the exclusion principle. Quarks must follow exclusion principle because they are fermions and have half integral spin (1/2). To solve this problem, it was considered that quarks have an additional property called colours and its possibilities are red, green and blue. The antiquark colours are antired, antigreen and antiblue.

According to colour hypothesis, each baryon consist of three quarks of different colours which satisfies the exclusion principle, since all quarks have different states even if two or three particles are identical, such combination is thought to be white. The antibaryon is made of antired, antigreen and antiblue quarks.

The meson is consist of quark of one colour and an antiquark of corresponding anticolour and thus cancelling the effect of colours. Thus the hadrons and antihadrons are colourless.

On deeper level, strong interactions are based on quark colour as the electromagnetic interactions are based on electric charge.

Proton and antiproton.

Neutron and antineutron.

Quarks confinement

Quarks confinement means we cannot isolate quarks.

Explanation of quarks confinement is based on the idea that, as quarks are connected by spring, the attractive force between two quarks increase with increase in their distance. Thus more energy is needed to isolate quark particles. But with enough energy quarks instead of seperating produces a quark antiquark pair, which result in a meson that escapes.

For example when an energetic 𝛾 photon reacts with neutron having composition udd as shown in figure causes a uū quark antiquark pair to come into existence. The udd + uū rearranges to form a proton (uud) and a negative π meson, the reaction is given as

Quarks confinement.

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Mass defect, packing fraction and binding energy.

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