Neutrinos are half-integer spin particles classified as fermions, and their behavior can be analyzed using the Fermi-Dirac distribution, defined by the equation $$f=\frac{1}{\exp(E/T)+1}$$. However, due to their elusive nature and low interaction rates, neutrinos rarely achieve thermal equilibrium in most systems, making the Fermi-Dirac distribution less applicable outside of specific conditions, such as the early universe. The discussion confirms that while the Fermi-Dirac distribution is theoretically relevant, it does not accurately predict neutrino distribution in typical environments.
PREREQUISITESStudents in physics, particularly those studying particle physics, astrophysics, or quantum mechanics, as well as researchers interested in neutrino properties and their implications in cosmology.
Thanks! Would it then be correct to say that, due to neutrinos being relatively non interactive compared to other fermions, the thermal-equilibrium distribution cannot predict their distribution in a system?vanhees71 said:Neutrinos are indeed fermions. I'm not sure what you mean by "Fermi-Dirac distribution". Usually one understands it to be the thermal-equilibrium distribution,
$$f=\frac{1}{\exp(E/T)+1}.$$
Since neutrinos are very elusive guys, it's very hard to imagine to have them in thermal equilibrium. Of course, in the very early universe they in fact were in thermal equilibrium.