pp and ̄pp elastic scattering

Pomeron in exclusive vector meson production

“…Following tradition [18], it is a customary practice to adopt a linear Pomeron trajectory in order to describe hadronic interactions. In a different approach [7,19] that provides a satisfactory fit to pp and pp data a square root trajectory similar to that of Eq.…”

Hadron diffractive processes: the structure of soft pomeron and colour screening

“…Still, with the energy increase it became obvious that the experimental data do not obey the GCF pomeron: Kaidalov and Ter-Martirosyan (KT) [2] suggested a supercritical pomeron with an intercept α P (0) = 1 + ∆ where ∆ > 0, that gives σ tot ∼ s ∆ ; in fitting to data the magnitude ∆ ≃ 0.12 was found. Donnachie and Landshoff (DL) [3] succeeded in the description of a wide range of experimental data on the diffractive processes using a supercritical pomeron with ∆ ≃ 0.08. As was obvious from the very beginning, the one-pomeron exchange amplitude with ∆ ∼ 0.1 (KTDL pomeron) is applicable in a restricted region of energies.…”

“…Naively, the problem of extending the model to the region of higher energies looked rather simple: one should introduce ∆ of the order of 0.1, following the suggestion of Refs. [2,3], and evaluate the corrections related to the two-pomeron exchange (these corrections are to be taken into account, because elastic and diffractive cross sections, σ el and σ DD , are determined by the imaginary parts of the two-pomeron exchange diagrams, and they are not small). However, the realization of this program with ∆ ≃ 0.08 faced a phenomenon which may be called a hidden unitarity violation: the description of experimental data with both one-pomeron ( Fig.…”

“…This fact does not agree with the statement made in [43] that colour screening affects the different growth rates of cross sections for different reactions. Concluding, we would like to underline the basic difference of the developed approach from that of Donachie-Landshoff [3,5,43]. In [3,5] soft diffractive amplitudes are due to the soft pomeron exchange with ∆ sof t = 0.08, while a new object -hard pomeron with ∆ hard = 0.3 -is introduced for the vector meson electroproduction processes γ * (Q 2 )V → V P [43].…”

Diffractive effects in spin-flipppamplitudes and predictions for relativistic energies

“…Those experiments, however, did not measure the polarization of the projectiles. Since the differential cross section (dσ/dt) at ISR energies is usually assumed to be dominated by the spin-non-flip amplitude, many of the models describing the diffraction in pp scattering do not take into account the contribution from spin-flip amplitudes [2,3,4]. Others do [5,6,7,8] but in this case they use data at lower energies [9].…”