Saturday, 20 July 2013

Particle Physics

This chapter deals with fundamental particle physics. If you have in depth knowledge of Particle physics then you may skip this chapter.

For  some decades Physicists have been trying to explain the cause of existence of matter and four fundamental forces. Several experiments were held to find the basic particles and their classification.

Four types of particles are : 

1. Fundamental Particles or Fermions : These include the most basic particles that mode

rn physics explains. These particles can be subdivided into matter and force carriers.

Matters : They are the basic building blocks. Leptons are Quarks are major matter builders. Leptons can be further sub-divided into neutrinos and electrons and another 4 non-stables.

Neutrino has 0 charge and extremely low mass. Electrons have a charge -1 and extremely low mass. Together neutrinos and electrons make major part of leptons.

Quarks have relatively higher mass and fractional charges. There are 6 types of quarks but again only two are stable in an ordinary matter. Three quarks together form a charge of +1.

u stands for up charge and d stands for down charge.

Gauge-Bosons or the force carriers : These include those particles which carry force or energy. They have no mass thus they are non-matter. Photons, gluons and W+ vector intermediate are major bosons and their existence has been proved. Gravitons (believed to be responsible for gravitational pull), X-bosons (non-matters as well as non-force carriers) and Higgs boson (responsible for Higgs field) are hypothetical, i.e their existence has not been completely proved.

What are God particles?

Have you ever heard of ghosts or something extra terrestrial force? Or some forces that are strange and science doesn't seem to explain it properly. Such forces are hypothetically best explained by Higgs Boson. Higgs Boson are bosonic particles responsible for carrying forces between particles, i.e they are responsible for creation of Higgs field. The Higgs Boson popped into existence and formed the Higgs Field after the Big bang. That field, according to the hypothesis, has the ability to tell (thus messenger) all the other particles, like quarks and neutrinos, how to behave etc. Higgs are responsible for all kinds of ghostly and super natural occurrences around our surrounding. However they are hypothetical, i.e their existence is not yet proved. Since they form the base to explain the super natural forces of nature so they are referred as God particles. In fact the existence of Higgs is easily believed by an athiests. Recently a Large Hadron Collider (LHC) has been built to prove the existence of God particles.

A Large Hadron Collider

2. Anti-particles : Most of the fundamental particles have antiparticles, i.e particles of their opposite charge. For example positron is anti-electron having a charge of +1. Anti quark has opposite charge of that of a quark. Anti proton have -1 charge. Anti neutron have 0 charge. Both Anti proton and Anti neutron are made up of anti-quarks. Anti neutrinos also exist with 0 charge.

3. Composite particles or Hadrons : These particles are formed by combining two or more than two fundamental particles. Thus there are 100s of composite particles. They are again sub-divided into Baryons and Mesons.

Baryons have relatively larger mass and contain three quarks. Protons and Neutrons are further sub-division. In proton, the quarks are arranged as 1 down and 2 up (See the picture) resulting in a charge of +1. In neutrons the quarks are arranged as 1 up 2 down resulting in charge 0. Since Protons and Neutrons are made up of same number of quarks, they have equal mass.

Mesons are made up of a quark and an anti quark. Positive pion is one such Meson with charge +1.

4. Exotic Particles : These includes the dark matter or dark energy carriers and magnetic monopoles whose existence is hypothetical.

Dark matter

Our principal concern would be Photons, Electrons and some Baryons which would be primarily used to study the nature of radiation and light.

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