This result is reversed for non-physical fields whose contributions to virtual processes ensure a unitary theory, called ghost fields. This result takes its usual form in 3 + 1 (“three-plus-one”) dimensions because world lines cannot form knots, making the braid group just the symmetric group; however, the nontrivial braid group in 2 + 1 (“two-plus-one”) dimensions causes this result to take a different form obeyed by anyons (“ANY-onz”). Proofs of this result require relativistic quantum field theory, but topological intuition for it is seen in the belt trick, in which a four pi rotation returns the belt to its original state. Per this result, the exchange operator leaves wave functions of one class of particles unchanged, while wave functions of another class of particles pick up a minus sign under exchange. For 10 points, name this theorem that states that half-integer spin particles obey the Fermi (“FAIR-mee”)–Dirac (“dih-RACK”) distribution and integer spin particles obey the Bose (“boze”)–Einstein distribution. ■END■
ANSWER: spin–statistics theorem [or spin–statistics relation or spin–statistics connection or spin–statistics correlation]
<Physics>
= Average correct buzz position