Can an even number of Fermions be a Bosonic system?

[Imanbk]

Hi everyone,

I've just done a problem where we are dealing with two protons with the same spin directions and the system is treated as a fermionic system.

I always had the notion that two (or an even number of) fermions, for opposite spin perhaps, act as bosons. Is this true? If so, when is it true and when does this picture breakdown?

Thanks for any clarifications on this one!

imanbk

 

[tom.stoer]

A system consisting of an even number of fermions is still as system of fermions. But if pairs of fermions form bound states with some binding energy ΔE then it may be possible to describe the system (at an energy scale E < ΔE) via bosonic quasi-particles, effective d.o.f. or something like that. One example are the Cooper pairs in a superconductor.