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| Author(s): |
Daniel Almeida Fagundes
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Física Gleb Wataghin |
| Defense date: | 2014-03-07 |
| Examining board members: |
Márcio José Menon;
Victor Paulo Barros Gonçalves;
Gastão Inácio Krein;
Arlene Cristina Aguilar;
Carola Dobrigkeit Chinellato
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| Advisor: | Adriano Antonio Natale; Márcio José Menon |
| Abstract | |
Just as Quantum Electrodynamics (QED) is the fundamental theory of electromagnetic interactions at the subatomic level, Quantum Chromodynamics (QCD) currently qualifies as the best candidate of an elementary theory of strong interactions - participating in hadronic reactions at typical distances ~ 1 fm (1015 m). As a fundamental theory, QCD seeks to describe the structure of hadrons and nuclei in terms of the elementary fields of quarks and gluons. On the one hand, many of its predictions have been confirmed in experiments using particle accelerators. On the other hand, several other phenomena still lack a full description in QCD and require thorough investigation, such as soft hadron-hadron scattering (at small momentum transfer) at high energies, the main object of study of this thesis. From the theoretical point of view, due to the absence of a formalism fully based on QCD, being able to treat systematically the nonperturbative sector, it becomes a challenge to explain the dynamical features of soft diffractive processes, elastic and inelastic dissociation, in fundamental terms. For this particular reason, studies of these processes have been done in the phenomenological scope, aiming to extract general properties of hadronic interactions at high energies. In this doctoral thesis we present a comprehensive study of elastic hadron scattering with focus in the energy frontier explored at the LHC, using empirical and phenomenological approaches to treat proton-proton and antiproton-proton scattering at center of mass energies in the range (s)^(1/2) = 5 GeV - 8 TeV. Moreover, we investigate possible scenarios of unitarity saturation in pp collisions and asymptotic properties of hadronic interactions. The results displayed here encompass three distinct approaches to elastic pp and _pp hadron scattering at high energies, being effective in the description of all experimental data analyzed. Firstly, we discuss the applicability of a QCD-inspired model to elastic scattering, with the main virtue of providing explicit connections with the dynamics of nonperturbative QCD, linked to recent results from lattice QCD and solutions of Schwinger-Dyson Equations (SDE) for the gluon propagator. In effect, the major goal of this approach, henceforth called DGM (Dynamical Gluon Mass), is to study the influence of a mass scale, m0, related to dynamical gluon mass generation at the infrared QCD sector. Secondly, one treats the problem of the rise of total, elastic and inelastic cross sections in proton-proton and antiproton-proton scattering from an empirical perspective, discussing three possible scenarios of saturation of the ratio between the total and elastic cross sections. Finally, we investigate the problem of the elastic differential cross section at the LHC in the light of an empirical model for the scattering amplitude by Barger and Phillips. We propose to use this model to describe the experimental data by the TOTEM Collaboration at 7 TeV and give predictions for the differential elastic cross section at LHC higher energies 8 TeV and 14 TeV. Using this model, we assume the saturation of two asymptotic sum rules for the elastic amplitude in order to estimate the energy frontier in which the black disc limit might be achieved (AU) | |
| FAPESP's process: | 11/00505-0 - Diffractive hadron scattering at high energies: eikonal representation and nonperturbative quantum chromodynamics |
| Grantee: | Daniel Almeida Fagundes |
| Support Opportunities: | Scholarships in Brazil - Doctorate |