PERT AND NON-PERT QCD EW AND SYMMETRY BREAKING BEYOND THE SM HEAVY FLAVOUR PHYSICS NEUTRINO AND NON ACCEL PHYSICS

Diffractive Processes

Alan Martin

Research in Durham has covered a range of both `hard' and `soft' diffractive phenomena.

• Diffractive deep inelastic scattering gamma p -> X p has been analyzed [1, 2] in terms of the production of X=q qbar, q qbar g systems via two-gluon exchange. For the case X=c cbar see [3]. For a review see [4].

• Diffractive vector meson production gamma p -> V p where V = rho, omega, phi, rho', J/Psi, Upsilon has been analysed in a series of papers [5, 6, 7, 8, 9]. A good description of all features of the data have been obtained, including in particular sigma_L/sigma_T.

• The central production of Higgs or dijets, with a rapidity gap on either side, has been calculated. Novel QCD techniques are required and estimates have been made to single log accuracy. The probability that the rapidity gaps survive population by secondaries from rescattering (that is from the underlying event) has been estimated [10, 11].

• The compatibility of diffractive hard scattering in p pbar and ep collisions has been demonstrated, and the breakdown of factorization between the two data sets has a natural physical explanation.

• Soft diffraction and the elastic slope in high energy collisions has been described in terms of multi-Pomeron approach, which embodies pion-loop insertions in the Pomeron trajectory, rescattering effects and high-mass diffractive dissociation. Predictions are made for soft processes at the LHC energy, and the survival probabilities of rapidity gaps are calculated for various diffractive processes.

Words by Alan Martin.