While other trajectories lead to falling
cross sections, the pomeron can lead to logarithmically rising cross sections — which, experimentally, are approximately constant ones. The identification of the pomeron and the prediction of its properties was a major success of the
Regge theory of
strong interaction phenomenology. In later years, a
Balitsky–Fadin–Kuraev–Lipatov (
BFKL)
pomeron (named after Ian Balitsky,
Victor Fadin,
Eduard A. Kuraev and
Lev Lipatov) was derived in further kinematic regimes from perturbative calculations in
quantum chromodynamics (QCD), but its relationship to the pomeron seen in soft high energy scattering is still not fully understood. One consequence of the pomeron hypothesis is that the cross sections of proton–proton and proton–antiproton scattering should be equal at high enough energies. This was demonstrated by the Soviet physicist
Isaak Pomeranchuk by
analytic continuation assuming only that the cross sections do not fall. The pomeron itself was introduced by
Vladimir Gribov, and it incorporated this theorem into Regge theory.
Geoffrey Chew and
Steven Frautschi introduced the pomeron in the West. The modern interpretation of
Pomeranchuk's theorem is that the pomeron has no conserved charges—the particles on this trajectory have the
quantum numbers of the
vacuum. The pomeron was well accepted in the 1960s despite the fact that the measured cross sections of proton–proton and proton–antiproton scattering at the energies then available were unequal. The pomeron carries no charges. The absence of electric charge implies that pomeron exchange does not lead to the usual shower of
Cherenkov radiation, while the absence of
color charge implies that such events do not radiate
pions. This is in accord with experimental observation. In high energy proton–proton and proton–antiproton collisions in which it is believed that pomerons have been exchanged, a
rapidity gap is often observed: This is a large angular region in which no outgoing particles are detected. ==Odderon==