Pomeron

In physics, the pomeron is a Regge trajectory, a family of particles with increasing spin, postulated in 1961 to explain the slowly rising cross section of hadronic collisions at high energies. It is named after Isaak Pomeranchuk.

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 BFKL pomeron was derived in other kinematic regimes from perturbative calculations in QCD, but its relationship to the pomeron seen in soft high energy scattering is still not completely 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. By the 1990s, the existence of the pomeron as well as some of its properties were experimentally well established, notably at Fermilab and DESY.

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