Particle Physics

Particle Physics is one of the branches of physics that deals with the study of elementary constituents of matter and radiation, and the interactions between them. Under normal circumstances in nature, the interactions between the particles do not occur. But elementary particles can be created and detected during the energetic collision of the particles. In modern particle physics, the focus is mainly on subatomic particles which have less structure than atoms.

Particle Physics

Particle Physics

Elementary Particle Physics

There are four types of fundamental interaction in nature- gravitational interaction, electromagnetic interaction, strong interaction and weak interaction.

  1. Gravitational Interaction: Gravitational interaction occurs due to the mass of the particle. The range of interaction is infinite. Gravitational interaction is always attractive. Gravitational interaction does not depend on the medium between the two particles. The nature of gravitational interaction is the exchange particle nature and exchange particle is the graviton. It is independent of velocity, the orientation of the object.
  2. Electromagnetic Interaction: Electromagnetic Interaction depends on the charge of the object. The range of interaction is infinite. It is attractive as well as repulsive. It is dependent on the medium between two particles. The electromagnetic interaction is also dependent on the velocity and orientation of the object. It has also exchange particle nature and the exchange particle is the photon.
  3. Strong Interaction: The range of interaction is short which causes nearest neighbour interaction. The strong interaction is independent of charge. It is also spin-dependent and isospin dependent. The strong interaction also depends on the velocity and orientation of the object. It has also exchange particle nature and exchange particle is mason such as nucleon-nucleon interaction. But exchange particle of infinitely strong interaction is gluon such as quark-quark interaction.
  4. Weak Interaction: It is mainly involved in nuclear decay like Beta decay. It has also exchange particle nature and exchange particle is gauge Boson.

Type of Elementary Particle

On the basis of spin, particles are two types-

  1. Boson: Boson has integer spin and it has a symmetric wave function. Boson follows B.E statics.
  2. Fermions: Fermions has half-integer spin and it has an antisymmetric wave function. It follows F-D statistics.

On the basis of interaction- elementary particles are two types a) Leptons b) Hadrons.

Leptons and Baryons are fermions but masons are boson. Leptons participate in electromagnetic interaction and as well as weak interaction but do not participate in the strong interaction. Hadrons participate in electromagnetic interaction as well as strong interaction but do not participate in weal interaction.

Conservation Laws:

There are two types of conservation laws – a) Exact conservation laws b) Approximate conservation laws.

a) Exact Conservation Laws: If these laws violets then the reaction is not allowed in nature. The laws of exact conservation are energy conservation, momentum conservation, angular conservation, charge conservation, charge parity time-reversal conservation.

b) Approximate Conservation laws: If these laws violets then the reaction may or may not be allowed. The laws of approximate conservation laws are isospin, the third component of isospin, strangeness, Charge parity conservation, Charge conjugation and time reversal conservation.


Isospin is an abstract quantity. It is not a physical quantity. Strong interactions are independent of charges such as inside the nucleus we cannot distinguish between neutron and proton. So to distinguish them we assign a quantum number that is isospin. Isospin assigns for hadron particles only. If ‘I’ is isospin then its third component has possible values of –I to +I. Isospin added as a vector but its third components can be added algebraically.

FAQs about Particle Physics

Q.1 Discuss the use of particle physics.

Answer: Particle physics is commonly used in chemistry, biology and material science researches. The researchers use particle physics in cameras which helps to collect signal from visible and infrared light and also from X-rays. It is also useful in the pharmaceutical industry. Particle physics is also useful for developing sensors and it has also huge use in computing and simulation.

Q.2: Give the definition of Electron.

Answer: Electron is a subatomic particle which is negatively charged. The charge of a single electron is equal to the charge of unit electrical charge.

Q.3 What is present inside a quark?

Answer: A quark is a tiny particle which is consists of protons and neutrons.

Q.4: An electron is negatively charged. Give the reason behind it.

Answer: An electron is said to be negatively charged which means they are surrounded by an invisible force field. This is an electrostatic field.

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