Related papers: Soft data and the hard pomeron
The introduction of a hard singularity in fits to total cross sections and to the ratio of real to imaginary parts enables to reproduce perfectly the data for sqrt(s)< 100 GeV using only simple-pole parametrisations, both for the soft and…
We review the evidence for the presence of a hard singularity in soft forward amplitudes, and give an estimate of its trajectory and couplings.
We show that the latest HERA measurements of F2 are compatible with the existence of a triple pole at J=1. Such a structure also accounts for soft forward hadronic amplitudes, so that the introduction of a new singularity is not necessary…
Using the largest data set available, we determine the best values that the data at t=0 (total cross sections and real parts of the hadronic amplitudes) give for the intercepts and couplings of the soft pomeron and of the rho/omega and a/f…
The soft pomeron successfully correlates a wide variety of data. Its properties seem rather simple: it couples to single quarks and its coupling factorises.
We present a preliminary report on the determination of the intercepts and couplings of the soft pomeron and of the rho/omega and f/a trajectories from the largest data set available for all total cross sections and real parts of the…
Recent models of soft diffraction include a hard pomeron pole besides the usual soft term. Such models violate the black-disk limit around Tevatron energies, so that they need to be supplemented by a unitarisation scheme. Several such…
We consider simple-pole descriptions of soft elastic scattering for pp, pbar p, pi+ p, pi- p, K+ p and K- p. We work at t and s small enough for rescatterings to be neglected, and allow for the presence of a hard pomeron. After building and…
We consider simple-pole descriptions of soft elastic scattering at small $t$ and $s$, and allow for the presence of a hard pomeron. We have built and analyzed an exhaustive dataset and we show that simple poles provide an excellent…
We show that simple Regge pole fits to the imaginary and the real part of the elastic amplitude in pp and pbar p collisions give a value of 1.096+0.012-0.009 for the pomeron intercept. Preliminary results of the new global fits to all…
Regge models for proton structure function with and without a hard Pomeron contribution are compared with all available data in the region $W>3$ GeV, $Q^{2}\leq 3000$ GeV$^{2}$ and $x<0.75$. It is shown that the data do not support a hard…
The hard pomeron component needed to reproduce small-x data seems to be present in elastic scattering at moderate energy. If this is the case, it is likely that the total cross section at the LHC will be appreciably larger than previously…
We prove a factorization theorem for heavy-to-light form factors. Our result differs in several important ways from previous proposals. A proper separation of scales gives hard kernels that are free of endpoint singularities. A general…
We extend our analysis of the soft behaviour of string amplitudes with massive insertions to closed strings at tree level (sphere). Relying on our previous results for open strings on the disk and on KLT formulae we check universality of…
We examine soft gluon physics, focusing on recently developed path integral methods. Two example applications of this technique are presented, namely the classification of soft gluon amplitudes beyond the eikonal approximation, and the…
We pose the question: how far can we push the QCD dipole model and the idea of QCD saturation to the kinematical regions traditionally associated with soft nonperturbative physics? The answer is that it works sufficiently well allowing a…
Soft pomeron fits reproduce all zero-Q2 data for light quarks, but run into problems at HERA for heavy mesons and for high Q2, and at the Tevatron for W diffractive production. I review the basic properties of the soft pomeron, and outline…
Recent data from LHC13 by the TOTEM Collaboration on $\sigma_{tot}$ and $\rho$ have indicated disagreement with all the Pomeron model predictions by the COMPETE Collaboration (2002). On the other hand, as recently demonstrated by Martynov…
We study transverse-momentum-dependent factorization at twist-3 for Drell-Yan processes. The factorization can be derived straightforwardly at leading order of $\alpha_s$. But at this order we find that light-cone singularities already…
A consistent and intuitive description of the twist-4 corrections to the hadron structure functions is presented in a QCD-improved parton model using time-ordered perturbative theory, where the collinear singularities are naturally…