Total Hadronic Cross Section Data and the Froissart-Martin Bound

The energy dependence of the total hadronic cross section at high energies is investigated with focus on the recent experimental result by the TOTEM Collaboration at 7 TeV and the Froissart-Martin bound. On the basis of a class of analytical parametrization with the exponent $\gamma$ in the leading logarithm contribution as a free parameter, different variants of fits to $pp$ and $\bar{p}p$ total cross section data above 5 GeV are developed. Two ensembles are considered, the first comprising data up to 1.8 TeV, the second also including the data collected at 7 TeV. We shown that in all fit variants applied to the first ensemble the exponent is statistically consistent with $\gamma$ = 2. Applied to the second ensemble, however, the same variants yield $\gamma$'s above 2, a result already obtained in two other analysis, by U. Amaldi \textit{et al}. and by the UA4/2 Collaboration. As recently discussed by Ya. I. Azimov, this faster-than-squared-logarithm rise does not necessarily violate unitarity. Our results suggest that the energy dependence of the hadronic total cross section at high energies still constitute an open problem.Comment: 20 pages, 10 figures, introduction extended and general references added to match editorial style, to appear in the Brazilian Journal of Physic

Análise do espalhamento elástico próton-próton e antipróton-próton e altas energias através de um formalismo tipo chou-yang com função de interação

Orientadores: Jose Bellandi Filho, Bruto Max Pimentel EscobarTese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb WataghinResumo: Apresenta-se um formalismo geométrico, tipo Chou-Yang, através do qual se obtém uma descrição unificada dos dados experimentais de espalhamento elástico próton-próton e antipróton-próton, na região 10 < Ös £ 630GeV. Nesse formalismo a opacidade resultante na colisão hadrônica é escrita como o produto de convolução de três funções bidimensionais, duas associadas às estruturas dos hádrons e uma à interação entre constituintes. A interpretação física obtida é que, com o aumento da energia, há um crescimento tanto do raio hadrônico, que tende a uma saturação em Ös @ 500 ~ 600GeV, como da intensidade da interação. Discute-se a possibilidade de a saturação no crescimento do raio estar relacionada com a produção de minijatosAbstract: A geometrical formalism of Chou-Yang type is presented, through which a unified description of pp and pp experimental data on elastic scattering at 10 < Ös £ 630GeV is achieved. In this formalism the resultant opaqueness in hadron collisions is given by the convolution of three bidimentional functions, two associated with the hadron structure and one with the interaction between constituents. The physical interpretation obtained is as follows: as the energy increases there is an increase both in the hadronic radius, which tend to a saturation at Ös @ 500 ~ 600GeV and in the interaction strength. It is argued that this saturation in the increase of the radius may be related to minijet productionDoutoradoFísicaDoutor em Ciência