MHV amplitudes MHV amplitudes In theoretical particle physics, maximally helicity violating amplitudes are amplitudes with n external gauge bosons, where n–2 gauge bosons have a particular helicity and the other two have the opposite helicity. These amplitudes are called MHV amplitudes, because at tree level, they violate helicity conservation to the maximum extent possible. The tree amplitudes in which all gauge bosons have the same helicity or all but one have the same helicity vanish. MHV amplitudes may be calculated very efficiently by means of the Parke–Taylor formula. Although developed for pure gluon scattering, extensions exist for massive particles, scalars (the Higgs)
Exchange operator Such motion is often not carried out in practice. Rather, the operation is treated as a "what if" similar to a parity inversion or time reversal operation. Consider two repeated operations of such a particle exchange: Therefore, formula_1 is not only unitary but also an operator square root of 1, which leaves the possibilities Both signs are realized in nature. Particles satisfying the case of +1 are called "bosons", and particles satisfying the case of −1 are called "fermions". The spin–statistics theorem dictates that all particles with integer spin are bosons whereas all particles with half-integer spin are fermions. The