Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (Ph. D.)--University of Hong Kong, 1994. / Includes bibliographical references.

University, Diss., 2004--Münster (Westfalen). / Erscheinungsjahr an der Haupttitelstelle: 2003.

Made available in DSpace on 2014-08-27T14:36:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-08-23Bitstream added on 2014-08-27T15:57:08Z : No. of bitstreams: 1 000775539.pdf: 468189 bytes, checksum: 90283774c4a5c934232a6b46ab03ce03 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Neste trabalho relembramos as fórmulas simples encontradas para as amplitudes MHV de gluons e gravitons nos contextos de super-Yang-Mills com supersimetria N = 4 e de supergravidade com supersimetria N = 8. A seguir, relembramos a prescrição proposta por Berkovits e Maldacena [5] que facilita o cálculo dessas amplitudes para gluons no contexto de supercordas abertas, e que reproduz os resultados corretos para 4 e 5 gluons além de se reduzir aos resultados de sYM no limite 'alfa linha' = 0, conforme veri?cado em [5] e [22]. Em seguida, estenderemos a prescrição de Berkovits-Maldacena para a supercorda fechada, usando-a primeiramente para calcular a amplitude MHV de 4 gravitons e conferindo o resultado com os encontrados na literatura por métodos usuais (resultado já obtido em [8]). Como contribuição original ao tema, demonstraremos que, no limite 'alfa linha' = 0, a prescrição reproduz o resultado de supergravidade encontrado por Hodges [17] / In this work we review the simple formulas found for MHV amplitudes of gluons and gravitons inside the contexts of super-Yang-Mills with supersymmetry N = 4 and supergravity with supersymmetry N = 8. We then review the prescription proposed by Berkovits and Maldacena [5] which simpli?es the calculation of those amplitudes for gluons inside the context of open superstrings, and which reproduces the correct results for 4 and 5 gluons, besides reducing to the sYM results in the 'alfa linha' = 0 limit, as veri?ed in [5] and [22]. Next, we extend the Berkovits-Maldacena prescription to the closed superstring, using it ?rst to calculate the MHV amplitude for 4 gravitons and verifying the result with the ones found in the literature by usual methods (result already obtained in [8]). As an original contribution to the subject, we will prove that, in the 'alfa linha' = 0 limit, the prescription gives the result of supergravity found by Hodges [17] / FAPESP: 11/02699-6

Orientador: Nathan Jacob Berkovits / Banca: Horatiu Stefan Nastase / Banca: Diego Trancanelli / Resumo: Neste trabalho relembramos as fórmulas simples encontradas para as amplitudes MHV de gluons e gravitons nos contextos de super-Yang-Mills com supersimetria N = 4 e de supergravidade com supersimetria N = 8. A seguir, relembramos a prescrição proposta por Berkovits e Maldacena [5] que facilita o cálculo dessas amplitudes para gluons no contexto de supercordas abertas, e que reproduz os resultados corretos para 4 e 5 gluons além de se reduzir aos resultados de sYM no limite 'alfa linha' = 0, conforme verificado em [5] e [22]. Em seguida, estenderemos a prescrição de Berkovits-Maldacena para a supercorda fechada, usando-a primeiramente para calcular a amplitude MHV de 4 gravitons e conferindo o resultado com os encontrados na literatura por métodos usuais (resultado já obtido em [8]). Como contribuição original ao tema, demonstraremos que, no limite 'alfa linha' = 0, a prescrição reproduz o resultado de supergravidade encontrado por Hodges [17] / Abstract: In this work we review the simple formulas found for MHV amplitudes of gluons and gravitons inside the contexts of super-Yang-Mills with supersymmetry N = 4 and supergravity with supersymmetry N = 8. We then review the prescription proposed by Berkovits and Maldacena [5] which simplifies the calculation of those amplitudes for gluons inside the context of open superstrings, and which reproduces the correct results for 4 and 5 gluons, besides reducing to the sYM results in the 'alfa linha' = 0 limit, as verified in [5] and [22]. Next, we extend the Berkovits-Maldacena prescription to the closed superstring, using it first to calculate the MHV amplitude for 4 gravitons and verifying the result with the ones found in the literature by usual methods (result already obtained in [8]). As an original contribution to the subject, we will prove that, in the 'alfa linha' = 0 limit, the prescription gives the result of supergravity found by Hodges [17] / Mestre

Dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in ful lment of the requirements for the degree of Master of Science. Johannesburg, 2017. / In this dissertation we tackle the question: is there an emergent Yang-Mills theory coming from the low energy description of branes and open strings? This new Yang-Mills theory has no connection to the original gauge symmetry of the CFT. We thus explore a large N but non-planar limit of the theory. This is done with new methods developed in group representation theory. A study the dilatation operator D in N = 4 SYM theory is done since its eigenvalue, the anomalous dimension, is mapped to the energy of the open string in the IIB string theory. The construction of the spherical harmonics from the harmonic expansion on the 3-sphere, S3, is done to understand the theory of the giant graviton's worldvolume. The light-front parton picture is examined, since it explains how one can \glue" single momentum modes together to obtain higher momentum modes, and we believe that this procedure is described dynamically using magnon bound states. Following from this, we work on determining the exact magnon bound state spectrum. Finally, we test our hypothesis and see if the spectrum of the bound states matches the harmonic spectrum from the harmonic expansion on the 3-sphere, S3. A non-trivial check is also performed to show that the bound state spectrum does indeed match the spectrum coming from N = 4 SYM. / LG2018

Random matrix models have found numerous applications in both Theoretical Physics and Mathematics. In the gauge-gravity duality, for example, the dynamics of the half- BPS sector can be fully described by the holomorphic sector of a single complex matrix model. In this thesis, we study the large-N limit of multi-matrix models at strong-coupling. In particular, we explore the significance of rescaling the matrix fields. In order to investigate this, we consider the matrix quantum mechanics of a single Hermitian system with a quartic interaction. We “compactify” this system on a circle and compute the first-order perturbation theory correction to the ground-state energy. The exact ground-state energy is obtained using the Das-Jevicki-Sakita Collective Field Theory approach. We then discuss the multi-matrix model that results from the compactification of the Higgs sector of N = 4 SYM on S4 (or T S3). For the radial subsector, the saddle-point equations are solved exactly and hence the radial density of eigenvalues for an arbitrary number of even Hermitian matrices is obtained. The single complex matrix model is parametrized in terms of the matrix valued polar coordinates and the first-order perturbation theory density of eigenstates is obtained. We make use of the Harish-Chandra- Itzykson-Zuber (HCIZ) formula to write down the exact saddle-point equations. We then give a complementary approach - based on the Dyson-Schwinger (loop) equations formalism - to the saddle-point method. We reproduce the results obtained for the radial (single matrix) subsector. The two-matrix integral does not close on the original set of variables and thus we map the system onto an auxiliary Penner-type two matrix model. In the absence of a logarithmic potential we derive a radial hemispherical density of eigenvalues. The system is regulated with a logarithm potential, and the Dobroliubov-Makeenko-Semenoff (DMS) loop equations yield an equation of third degree that is satisfied by the generating function. This equation is solved at strong coupling and, accordingly, we obtain the radial density of eigenvalues.

Esta tese estuda as contribuições proporcionais a In(T) da função de três pontos na teoria de Yang-Mills no calibre axial temporal na ordem de um loop no limite de altas temperaturas. Nós provamos que tais contribuições satisfazem uma identidade de Ward abeliana que as relaciona com o tensor de polarização do glúon, concluindo que são invariantes de Lorentz e têm a mesma estrutura dos pólos ultravioleta que ocorrem a temperatura zero. Usando uma simples prescrição para as constantes de renormalização e as equações do grupo de renormalização a temperatura finita, foi possível mostrar que a constante de acoplamento efetiva decai logaritmicamente em função da temperatura, de acordo com a liberdade assintótica, e é idêntica ao resultado obtido numa classe geral de calibres covariantes. / This thesis studies the In(T) contributions of the three-point function in the Yang-Mills theory in the temporal axial gauge at one-loop level in high-temperature limit. We proved that such contributions satisfy an abelian Ward identity which relates them with the gluon polarization tensor, concluding that they are Lorentz invariant and have the same structure of the ultraviolet poles which occur at zero temperature. Using a simple prescription for the renormalization constants and the finite-temperature renormalization group equations, it was possible to show that the effective coupling constant decreases logarithmically as a function of temperature, in accordance with asymptotic freedom, and is identical to the results obtained in a general class of covariant gauges.

Η πιο κάτω εργασία έχει σκοπό να περιγράψει την κβαντική μηχανική. Θα γίνει μια προσπάθεια συνδυασμού με την σχετικότητα σαν μια ενιαία θεωρία. Στη συνέχεια θα συζητηθεί η κβαντικη θεωρία πεδίων. Τελος θα συζητηθεί το ηλεκτρομαγνητικό πεδίο οι θεωρίες βαθμίδος και το πεδίο Yang-Mills. / The following essay will discuss the quantum theorem. It will present the field theorem and later we will discuss the Yang-Millw field.

Esta tese estuda as contribuições proporcionais a In(T) da função de três pontos na teoria de Yang-Mills no calibre axial temporal na ordem de um loop no limite de altas temperaturas. Nós provamos que tais contribuições satisfazem uma identidade de Ward abeliana que as relaciona com o tensor de polarização do glúon, concluindo que são invariantes de Lorentz e têm a mesma estrutura dos pólos ultravioleta que ocorrem a temperatura zero. Usando uma simples prescrição para as constantes de renormalização e as equações do grupo de renormalização a temperatura finita, foi possível mostrar que a constante de acoplamento efetiva decai logaritmicamente em função da temperatura, de acordo com a liberdade assintótica, e é idêntica ao resultado obtido numa classe geral de calibres covariantes. / This thesis studies the In(T) contributions of the three-point function in the Yang-Mills theory in the temporal axial gauge at one-loop level in high-temperature limit. We proved that such contributions satisfy an abelian Ward identity which relates them with the gluon polarization tensor, concluding that they are Lorentz invariant and have the same structure of the ultraviolet poles which occur at zero temperature. Using a simple prescription for the renormalization constants and the finite-temperature renormalization group equations, it was possible to show that the effective coupling constant decreases logarithmically as a function of temperature, in accordance with asymptotic freedom, and is identical to the results obtained in a general class of covariant gauges.