The diffractive production of two jets in deep inelastic e± p scattering is mea- sured in the kinematic region of photon virtuality 4 < Q2 < 80 GeV2 , inelasticity 0.1 < y < 0.7, momentum fraction xIP < 0.03, proton ver- tex momentum transfer |t| < 1 and mass of a dissociative baryonic system MY < 1.6 GeV. Diffractive events are identified with the large rapidity gap technique. Integrated and single differential cross sections are measured for jets of transverse momenta p∗ T1 > 5.5 GeV and p∗ T2 > 4.0 GeV and pseudora- pidities −3 < η∗ 1,2 < 0. The data were collected by the H1 experiment at the HERA collider in years 2005-2007, corresponding to an integrated luminosity of 283.7 pb−1 . The measurements are compared with NLO predictions based on the DGLAP parton evolution.

We derive the regularised evolution equations for the parton distribution functions that include tensorgluons.

Title: Analysis of dijet events in diffractive ep interactions with tagged leading proton at the H1 experiment Author: Richard Polifka Department: Institute of Particle and Nuclear Physics Supervisor: RNDr. Alice Valkárová, DrSc. Supervisor's e-mail address: avalkar@mail.desy.de Abstract: An inclusive dijet production in diffractive deep-inelastic scattering is measured. The diffractive selection is based on tagging of the leading proton in the Forward Proton Spectrometer. The statistics of events obtained during the HERA II running period (integrated luminosity of 156.7 pb−1 ) enables the measurement of jet final states with leading proton for the first time. The data cover the phase space of xIP < 0.1, |t| <= 1.0 GeV2 and 4 <= Q2 <= 110 GeV2 . The dijet data are compared with the next to leading order predictions of the quantum chromodynamics (QCD). The phase space of diffractive dijets is in this analysis by factor of 3 in xIP larger than in previous measurements. The QCD predictions based on the DGLAP parton evolution describe the measured data well even in a non-DGLAP enriched phase space where one on the jets goes into the region close to the direction of the outgoing proton. The measured single-differential cross sections are compared to several Monte Carlo models with different treatment of...

The environment inside the atomic nucleus is one of the most fascinating arenas for the study of quantum chromodynamics (QCD). The strongly-interacting nature of the nuclear medium affects the nature of both QCD processes and the quark-gluon structure of hadrons, allowing several unique aspects of the strong nuclear force to be investigated in reactions involving nuclear targets. The research presented in this dissertation explores two aspects of nuclear QCD: firstly, the partonic structure of the nucleus itself; and secondly, the use of the nucleus as a micro-laboratory in which QCD processes can be studied. The partonic structure of the nucleus is calculated in this work by deriving and utilizing a convolution formula. The hadronic structure of the nucleus and the quark-gluon structure of its constituent nucleons are taken together to determine the nuclear partonic structure. Light cone descriptions of short range correlations, in terms of both hadronic and partonic structure, are derived and taken into account. Medium modifications of the bound nucleons are accounted for using the color screening model, and QCD evolution is used to connect nuclear partonic structure at vastly different energy scales. The formalism developed for calculating nuclear partonic structure is applied to inclusive dijet production from proton-nucleus collisions at LHC kinematics, and novel predictions are calculated and presented for the dijet cross section. The nucleus is investigated as a micro-laboratory in vector meson photoproduction reactions. In particular, the deuteron is studied in the break-up reaction γd → Vpn, for both the ϕ(1020) and J/ψ vector mesons. The generalized eikonal approximation is utilized, allowing unambiguous separation of the impulse approximation and final state interactions (FSIs). Two peaks or valleys are seen in the angular distribution of the reaction cross section, each of which is due to an FSI between either the proton and neutron, or the produced vector meson and the spectator nucleon. The presence and size of the latter FSI valley/peak contains information about the meson-nucleon interaction, and it is shown that several models of this interaction can be distinguished by measuring the angular distribution for the deuteron breakup reaction.

Cette thèse décrit la mesure précise de la fonction de structure polarisée g1n du neutron menée par la collaboration E154 à l'automne 1995 auprès de l'accélérateur linéaire de Stanford aux Etats-Unis, par diffusion profondément inélastique inclusive d'un faisceau d'électrons polarisé de 48.3 GeV sur une cible d'Hélium 3 polarisée. Les électrons diffusés ont été détectés par deux spectromètres permettant de couvrir le domaine cinématique en x Bjorken : 0.014 < x < 0.7 et en quadritransfert carré : 1 GeV2 < Q2 < 17 GeV2 à une valeur moyenne Q2 = 5 GeV2. Deux calorimètres électromagnétiques pris en charge par le LPC de Clermont-Ferrand et le SphN du CEA-Saclay ont été utilisés pour déterminer l'énergie des électrons diffusés et pour rejeter le bruit de fond hadronique. Pour cela, nous avons développé un automate cellulaire et un réseau de neurones, largement décrits dans ce manuscrit. L'analyse de la mesure de la fonction de structure g1n menée à Clermont-Fd et exposée dans ce manuscrit nous a conduit à l'intégrale sur la région mesurée : intégrale (g1n(x)dx, xmin=0.0135, xmax=0.7) = -0.03 +- 0.003 STAT +- 0.004 SYST +- 0.001 EVOL à Q2 = 5 GeV2 où nous avons fait évoluer nos mesures vers Q2 = 5 GeV2 à l'aide des équations d'évolution DGLAP à l'ordre sous-dominant en utilisant une paramétrisation mondiale des distributions de partons polarisées. La règle de somme d'Ellis et Jaffe sur le neutron est clairement violée par nos mesures. Pour les différents extrapolations envisagées à bas x, notre intégrale est compatible avec la règle de somme de Bjorken. Nous avons estimé la contribution du spin des quarks au spin du nucléon à DelatSigma = 29 ± 6 % dans le schéma MS barre et à DeltaSigma = 37 ± 7 % dans le schéma AB, à Q2 = 5 GeV2. La contribution du spin des gluons au spin du nucléon semble positive et comprise entre 0 et 2 à cette échelle.