P oS(DIS 2010)111 Fluctuations and Saturation in Diffractive Excitation

Diffractive excitation is usually described by the Good–Walker formalism for low masses, and by the triple-Regge formalism for high masses. In the Good–Walker formalism the cross sec-tion is determined by the fluctuations in the interaction. By taking the fluctuations in the BFKL ladder into account, it is possible to describe both low and high mass excitation in DIS and pp scattering by the Good–Walker mechanism. In high energy pp collisions the fluctuations are strongly suppressed by saturation. This suppression is strongest for central collisions, which im-plies that diffractive excitation in pp collisions is largest within a ring with radius about 1 fm. MC simulations of the Dipole Cascade Model also reproduce the triple-Regge form with a bare pomeron represented by a simple pole with α(0) = 1.21, α ′ = 0.2 GeV−2, and an almost constant triple-pomeron coupling