Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 147 for “"Quantum chromodynamics"”.
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Transport coefficients in quantum chromodynamics
… from the lowest order scattering diagrams of quantum chromodynamics. We study a pure quark system, a pure gluon system and a quark antiquark (qq) mixture. For mixtures of quarks, antiquarks and gluons, we find the shear viscosity, heat conductivity and cross-coefficients. The coefficients …
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Quantum chromodynamics at low energies
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 1992
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Generalized Compton Amplitudes in Quantum Chromodynamics
<p>In this dissertation we describe results of our studies of generalized Compton amplitudes. We have calculated the one-loop corrections to the amplitude in the coordinate representation in terms of nonlocal string light-ray operators. We have also developed a consistent approach to the problem of …
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Higher-Order Calculations in Quantum Chromodynamics
… several techniques and advances in higher-order Quantum Chromodynamics (QCD) calculations are presented. There is a particular focus on 2-loop 5-point massless QCD amplitudes, which are currently at the frontier of higher-order QCD calculations. Firstly, we study the …
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Perturbative quantum chromodynamics in a cavity
BRS invariant Quantum Chromodynamics is quantized in a static spherical cavity, subject to the boundary conditions of the MIT group. Using the Gell-Mann and Low theorem and a modified version of Goldstones theorem we formulate perturbation theory. In 4th order perturbation theory we calculate the …
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Hadron -hadron scattering in lattice quantum chromodynamics
… in fully dynamical, mixed-action Lattice Quantum Chromodynamics using the MILC gauge ensembles in a non-perturbative simulation are discussed. In particular, calculations of the pi+sum+, pi+xi 0, K+p, K+n, and K¯ 0xi0 scattering lengths are presented, and are the main subject of this …
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Virtual Compton Scattering Processes in Quantum Chromodynamics
<p>Applications of perturbative QCD to deeply virtual Compton scattering and hard exclusive meson electroproduction processes require a generalization of usual Parton distributions for the case when long-distance information is accumulated in nonforward matrix elements [special characters omitted] …
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Meson Photo-Couplings From Lattice Quantum Chromodynamics
… featuring a vector current insertion in lattice Quantum Chromodynamics. These three-point functions, in general, contain information about many radiative transition matrix elements simultaneously. We develop and implement the technology necessary to isolate a single matrix element via the use of …
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Functional Renormalization Group Methods in Quantum Chromodynamics
… functional Renormalization Group methods to Quantum Chromodynamics (QCD). First we calculate the mass shift for the pion in a finite volume in the framework of the quark-meson model. In particular, we investigate the importance of quark effects. As in lattice gauge theory, we find that the …
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Vacuum structure and condensates in quantum chromodynamics
Klassiek wordt de grondtoestand van een model bepaald door na te gaan of er een globaal minimum van de potentiaal bestaat. Dit minimum correspondeert met de meest stabiele toestand van het model. Het concept van een klassieke potentiaal kan uitgebreid worden tot de zogenaamde kwantum effectieve …
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Inclusive and Exclusive Compton Processes in Quantum Chromodynamics
<p>In our work, we describe two types of Compton processes. As an example of an inclusive process, we consider the high-energy photoproduction of massive muon pairs off the nucleon. We analyze the process in the framework of the QCD parton model, in which the usual parton distributions emerge as a …
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Flavour SU(3) symmetry breaking in quantum chromodynamics
The subject of this thesis is the determination of the size of SU(3) flavour symmetry breaking in the QeD vacuum, as measured by the ratio of the strange to non-strange quark vacuum condensates <ss>/<uu> (with <ūu>
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The gluon self-energy in cavity quantum chromodynamics
… to regularize divergent loop diagrams in cavity quantum chromodynamics is discussed, which is closely related to free space dimensional regularization. In this cavity regularization method, the energy shift is expressed as the integral of a divergent spectral function, from which the divergence …
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Canonical quantization and quantum chromodynamics in a cavity
… formalism is applied to the Lagrange density of chromodynamics in a general covariant gauge. The physical states are characterized by their BRS-invariance. We develop the quantum theory of the interacting fields in the Dirac picture, based on the Gell-Mann and Low Theorem and the Dyson expansion …
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Quantum Chromodynamics and the Precision Phenomenology of Heavy Quarks
… of the theory of strong interactions, Quantum Chromodynamics (QCD), with particular reference to the ongoing experimental program at the Large Hadron Collider in CERN. The current progress in precision measurement of Standard Model processes at the LHC experiments must be matched with …
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Weak decays of beautiful pseudoscalar mesons with Lattice Quantum Chromodynamics
… a selection of decays of $B$ mesons with Lattice Quantum Chromodynamics. After introducing these modern methods, I report on my progress on calculating the vector current form factors for $B_c \to D_s$. This decay is allowed at the one-loop level and so my vector current form factors will be used, …
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Quark and Gluon Propagation in Two-Colour Quantum Chromodynamics at Finite Density
Two-colour quantum chromodynamics has been studied on the lattice at finite chemical potential. The phase diagram of the theory with respect to varying temperatures and densities is presented. Deconfinement and normal to superfluid phase transitions are investigated. Chromoelectric and …
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Quantum Chromodynamics with Eight and Twelve Degenerate Quark Flavors on the Lattice
This thesis is concerned with the behavior of non-abelian gauge theories with many flavors of fermions. In perturbation theory, an infrared fixed point is predicted to exist, and theories become conformal in the low energy limit, in non-abelian gauge theories with the number of fermions just below …
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An Intermediate Representation for Expressing and Optimizing Computations in Lattice Quantum Chromodynamics
The field of Lattice Quantum Chromodynamics faces massive scaling problems because of the large iteration spaces of the sums required which scale with the factorial of the number of atoms represented. The LQCD IR and rewrite system from this thesis allows tackling these scaling problems quicker and …
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Running Coupling Constant and Transition From Low to High Energies in Quantum Chromodynamics
<p>The remarkable feature of QCD is that the coupling constant (the strength of the interaction) depends on the energy of the interacting particles. At high energies, the coupling constant vanishes and QCD becomes asymptotically free. However, at lower energy, the running coupling constant …
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