Energy Conservation: Beta Ray & Neutrino

In summary, the energy of a beta ray and neutrino is equal to the mass difference of the nucleus before and after the reaction, which is about 1 MeV. However, the mass of a W boson is 80 MeV, causing the least energy of the electron and neutrino to be 80 MeV. This difference in energy may seem like a violation of energy conservation, but it is due to the W boson being a virtual particle and not having to follow the same rules as real particles. Particle physicists refer to this as being "off the mass shell." The mass of a real W boson is actually 80 GeV, but the virtual W does not follow this same mass-energy relationship.
  • #1
fxdung
388
23
Energy of beta ray and neutrino is equal Q=M(mass) of nucleous before-M of nucleous after,so it about 1Mev.But the mass of W boson is 80 MeV,so the least energy of electron and neutrino must be 80 MeV.
Why there is the difference?Why does it seem that energy were not conservation?
 
Physics news on Phys.org
  • #2
The W is a virtual particle. It's "off shell," so it doesn't have to have an energy and momentum that are consistent with its mass.
 
  • #3
Energy and momentum are both conserved at each vertex of a Feynman diagram, so one can calculate the energy and momentum of the virtual W from the energies and momenta of the outgoing (anti)neutrino and electron. However, because the W is virtual, ##\sqrt{E^2 - (pc)^2}## does not equal the mass of a real W. For a real W, ##\sqrt{E^2 - (pc)^2} = m_W c^2##.

Particle physicists use the jargon that real (virtual) particles are "on (off) the mass shell," referring to the quantity ##\sqrt{E^2 - (pc)^2}##. Or as Ben said, just "on (off) shell" for short.
 
Last edited:
  • Like
Likes bcrowell
  • #4
I can understand your teaching! Thanks very much!
 
  • #5
Also, the mass of the W is 80 GeV.
 
  • Like
Likes bcrowell

1. What is energy conservation?

Energy conservation refers to the practice of reducing energy consumption in order to preserve natural resources and protect the environment. It involves using energy more efficiently and finding alternative sources of energy to reduce our reliance on fossil fuels.

2. What is Beta Ray?

Beta Ray, also known as beta radiation, is a type of ionizing radiation that is emitted from unstable atoms. It consists of high-energy electrons or positrons that are released during the process of radioactive decay.

3. What is Neutrino?

Neutrino is a subatomic particle that has no electric charge and a very small mass. It is one of the fundamental building blocks of matter and is constantly moving through space at the speed of light.

4. How do Beta Ray and Neutrino relate to energy conservation?

Beta Ray and Neutrino are both forms of energy that can be harnessed and used as alternative sources of energy. Beta Ray can be converted into electricity through processes like beta decay, while Neutrinos can be harnessed through nuclear reactions or captured from the sun to generate power.

5. What are the benefits of using Beta Ray and Neutrino for energy conservation?

The use of Beta Ray and Neutrino as alternative sources of energy can help reduce our reliance on fossil fuels, which contribute to air and water pollution, climate change, and other environmental issues. Additionally, these sources of energy are renewable and have lower carbon emissions, making them more sustainable for the environment in the long run.

Similar threads

  • High Energy, Nuclear, Particle Physics
Replies
32
Views
2K
  • High Energy, Nuclear, Particle Physics
Replies
3
Views
2K
  • High Energy, Nuclear, Particle Physics
Replies
4
Views
1K
  • High Energy, Nuclear, Particle Physics
Replies
5
Views
2K
  • High Energy, Nuclear, Particle Physics
Replies
3
Views
2K
  • High Energy, Nuclear, Particle Physics
Replies
4
Views
2K
  • High Energy, Nuclear, Particle Physics
Replies
4
Views
2K
  • High Energy, Nuclear, Particle Physics
Replies
11
Views
1K
  • High Energy, Nuclear, Particle Physics
Replies
2
Views
1K
  • High Energy, Nuclear, Particle Physics
Replies
17
Views
2K
Back
Top