The hard pomeron in soft data

Abstract

We show that the data for the total cross section and for the real part of the elastic amplitude indicate the presence of a hard pomeron in pi p and Kp elastic scattering at t=0, compatible with that observed in deep inelastic scattering. We show that such a hard pomeron is also compatible with pp and pbar p data, provided one unitarises it at high energy.Comment: 13 pages, 5 figures, plain LaTeX, references added and typos remove

Soft data and the hard pomeron

“…However, if we use only one simple pole for the pomeron (i.e. if we set H b = 0 in (4), we still cannot get a fit comparable to those obtained using (5,6). Table 1 Parameters obtained in the fit from 5 to 100 GeV.…”

“…Following [6], we want here to explore another possibility: we shall assume that "bare" exchanges of Regge trajectories account for most of the elastic amplitude, and that unitarisation and cuts have a small, negligible, effect. This is the standard assumption that lead Donnachie and Landshoff [7] to a very simple and successful description of soft scattering, based on the exchange of two degenerate leading meson trajectories and of a soft pomeron.…”

Effective transverse radius of nucleon in high-energy elastic diffractive scattering

“…According to our assumption, the only sources of the integrand singularities in the region Re j > − 5) where the functions α ± n (t) are the roots of the equations m 2 ± ( j) − t = 0 and, thus, they correspond to the eikonal poles in the complex j-plane. These poles are called Regge poles, and the functions α ± n (t) are called Regge trajectories.…”

“…The results of fitting α P (t) and g P (t) to the experimental differential cross sections at √ s > 500 GeV and 0.005 GeV 2 < −t < 2 GeV 2 [5][6][7][8][9][10][11][12][13][14] are presented in Tables 1, 2, and 3 and Fig. 1.…”

Diffractive Electroproduction of ρ Mesons

“…It has been found [21,22] that the inclusion of a hard pomeron in the soft data is possible and it is a necessary ingredient to obtain a good fit for all soft data. However, it is possible to assume [23] that the hard singularities manifest themselves only in the photon scattering, because the photon includes a non hadronic phase in addition to the hadronic phase. This non hadronic phase is believed to be responsible for the hard singularity.…”