i want to know the details of weak force?

Answer 1

The weak interaction (often called the weak force or sometimes the weak nuclear force) is one of the four fundamental interactions of nature. In the Standard Model of particle physics, it is due to the exchange of the heavy W and Z bosons. Its most familiar effect is beta decay (of neutrons in atomic nuclei) and the associated radioactivity. The word "weak" derives from the fact that the field strength is some 1013 times less than that of the strong force.

Properties:
The weak interaction affects all left-handed leptons and quarks. It is the only force affecting neutrinos (except for gravitation, which is negligible on laboratory scales). The weak interaction is unique in a number of respects:

It is the only interaction capable of changing flavour.
It is the only interaction which violates parity symmetry P (because it only acts on left-handed particles). It is also the only one which violates CP.
It is mediated by heavy gauge bosons. This unusual feature is explained in the Standard Model by the Higgs mechanism.
Due to the large mass of the weak interaction's carrier particles (about 90 GeV/c2), their mean life is limited to about 3×10−25 seconds by the uncertainty principle. Even at the speed of light this effectively limits the range of the weak interaction to 10−18 meters, about 1000 times smaller than the diameter of an atomic nucleus.

Since the weak interaction is both very weak and very short range, its most noticeable effect is due to its other unique feature: flavour changing. Consider a neutron (quark content udd; one up quark, two down quarks). Although the neutron is heavier than its sister nucleon, the proton (quark content uud), it cannot decay into a proton without changing the flavour of one of its down quarks. Neither the strong interaction nor electromagnetism allow flavour changing, so this must proceed by weak decay. In this process, a down quark in the neutron changes into an up quark by emitting a W boson, which then breaks up into a high-energy electron and an electron antineutrino. Since high-energy electrons are beta radiation, this is called a beta decay.

Due to the weakness of the weak interaction, weak decays are much slower than strong or electromagnetic decays. For example, an electromagnetically decaying neutral pion has a life of about 10−16 seconds; a weakly decaying charged pion lives about 10−8 seconds, a hundred million times longer. A free neutron lives about 15 minutes, making it the unstable subatomic particle with the longest known mean life.

Answer 2

a fundamental force of nature that underlies some forms of radioactivity, governs the decay of unstable subatomic particles such as mesons, and initiates the nuclear fusion reaction that fuels the Sun. The weak force acts upon all known fermions—i.e., elementary particles with half-integer values of intrinsic angular momentum, or spin. Particles interact through…


weak force... (75 of 402 words)

There are three basic types of weak interaction vertices (up to charge conjugation and crossing symmetry). Two of them involve charged bosons, they are called "charged current interactions." The third type is called "neutral current interaction."

A charged lepton ( such as an electron or a muon ) can emit or absorb a W boson and convert into a corresponding neutrino.
A down-type quark (with charge -1/3) can emit or absorb a W boson and convert into a superposition of up-type quarks. Conversely, an up-type quark can convert into a superposition of down-type quarks. The exact content of this superposition is given by CKM matrix.
Either a lepton or a quark can emit or absorb a Z boson.