Soft pomerons and the forward LHC data

Abstract

Recent data from LHC13 by the TOTEM Collaboration on σ tot and ρ have indicated disagreement with all the Pomeron model predictions by the COMPETE Collaboration (2002). On the other hand, as recently demonstrated by Martynov and Nicolescu (MN), the new σ tot datum and the unexpected decrease in the ρ value are well described by the maximal Odderon dominance at the highest energies. Here, we discuss the applicability of Pomeron dominance through fits to the most complete set of forward data from pp andpp scattering. We consider an analytic parametrization for σ tot (s) consisting of non-degenerated Regge trajectories for even and odd amplitudes (as in the MN analysis) and two Pomeron components associated with double and triple poles in the complex angular momentum plane. The ρ parameter is analytically determined by means of dispersion relations. We carry out fits to pp andpp data on σ tot and ρ in the interval 5 GeV -13 TeV (as in the MN analysis). Two novel aspects of our analysis are: (1) the dataset comprises all the accelerator data below 7 TeV and we consider three independent ensembles by adding: either only the TOTEM data (as in the MN analysis), or only the ATLAS data, or both sets; (2) in the data reductions to each ensemble, uncertainty regions are evaluated through error propagation from the fit parameters, with 90 % CL. We argument that, within the uncertainties, this analytic model corresponding to soft Pomeron dominance, does not seem to be excluded by the complete set of experimental data presently available.

Convergence properties of Lévy expansions: implications for Odderon and proton structure

“…The recent TOTEM results [4,5] generated a burst of high level and intense theoretical debate about the correct interpretation of these data, see Refs. [15][16][17][18][19][20][21][22][23][24][25][26][27]. All possible extreme views were present among these first interpretative papers, including claims for a maximal Odderon effect [23] and claims of lack of any significant Odderon effects, Refs.…”

CGC/saturation approach: Secondary Reggeons andρ=Re/Imdependence on energy

“…The main motivation for this is our need to describe the energy behaviour of the ratio ρ = Re/Im of the scattering amplitude, to which the secondary reggeons make a significant contribution. The new TOTEM data [12] shows that the value of ρ = 0.1 ± 0.01(0.09 ± 0.01) is lower than expected, and this ignited the hot discussion about the possible contribution of the odderon [13][14][15][16][17][18][19][20]. The odderon contribution to the negative signature appears naturally in perturbative QCD, with an intercept which is equal to zero [21,22].…”

Forward elastic scattering and Pomeron models

“…In the second analysis, we have considered one Pomeron model with 6 free parameters and have evaluated the uncertainty regions with confidence level (CL) of 90 %. We have concluded that the model seems not to be excluded by the bulk of experimental data presently available [27].…”