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Teses / dissertações sobre o tema "Particles (Nuclear physics) Chirality"

Autor: Grafiati

Publicado: 4 de junho de 2021

Última modificação: 1 de agosto de 2024

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1

Uwitonze, Pierre Celestin. "Assignment of spin and parity to states in the nucleus ¹⁹⁶T1." Thesis, Rhodes University, 2015. http://hdl.handle.net/10962/d1017903.

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This work presents a study of high-spin states in the nucleus ¹⁹⁶Tl via γ-spectroscopy. ¹⁹⁶Tl was produced via the ¹⁹⁷Au(⁴He,5n) ¹⁹⁶Tl reaction at a beam energy of 63 MeV. The γ-γ coincidence measurements were performed using the AFRODITE γ-spectrometer array at iThemba LABS. The previous level scheme of ¹⁹⁶Tl has been extended up to an excitation of 4071 keV including 24 new γ-ray transitions. The spin and parity assignment to levels was made from the directional correlation of oriented nuclei (DCO) and linear polarization anisotropy ratios. An analysis of the B(M1)/B(E2) ratios was found to be consistent with the configuration of πh₉/₂♁vi₁₃/₂ for the ground state band. Although no chiral band was found in ¹⁹⁶TI and ¹⁹⁸TI.

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2

Detmold, William. "Nonperturbative approaches to quantum chromodynamics." Title page, contents and abstract only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phd4817.pdf.

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3

Pupin, Joel César [UNESP]. "Simetria quiral: fótons, píons e núcleons." Universidade Estadual Paulista (UNESP), 1994. http://hdl.handle.net/11449/132669.

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Made available in DSpace on 2016-01-13T13:27:34Z (GMT). No. of bitstreams: 0 Previous issue date: 1994. Added 1 bitstream(s) on 2016-01-13T13:33:01Z : No. of bitstreams: 1 000524316.pdf: 3132245 bytes, checksum: cdfd47a27f819ee95d467ba02ef476d7 (MD5)<br>Este trabalho consiste no estudo do papel das simetrias quiral e de calibre eletromagnético, da constante 'g IND. A' e do tipo de acoplamento pion-núcleon em três processos: fotoprodução de um píon e de dois píons e interação fóton-núcleon. Os dois primeiros processos são tratados na aproximação em árvore, enquanto que no último são considerados também diagramas envolvendo um loop. O papel das simetrias é analisado investigando-se a existência de relações entre os vários diagramas de um dado processo. Já o papel do tipo de acoplamento pion-núcleon é analisado, comparando-se os resultados obtidos por meio de dois modelos de implementação da simetria quiral: o sigma linear e o não linear de Weinberg. Analogamente, o papel de 'g IND. A' é avaliado pela inspeção direta das expressões obtidas para os vários processos. Este estudo mostrou que, apenas no processo envolvendo dois píons externos a simetria quiral é relevante. Em particular, a simetria quiral é irrelevante para o fator de forma eletromagnético devido à nuvem piônica do núcleon, pelo menos no contexto das correções de um loop consideradas. Estes resultados constituem pontos de partida para o estudo mais abrangente do papel da simetria quiral em abordagens não perturbativas, tais como a do modelo de Skyrme<br>In this Work we study the role played by chiral and electromagnetic gauge symmetries, the weak constant 'g IND. A' and pion-nucleon couplings in three processes; single and double pion photo production and photon-nucleon interaction. The first two of them are treated at tree levei, whereas the last one includes one loop corrections. The role of the symmetries is analyzed considering the existence of relationships among various diagrams contributing to a given process. The influence of the way pions couple to nucleons is studied by comparing results obtained by means of the linear sigma model and the non linear model proposed by Weinberg. Finally, the role of 'g IND. A' is assessed by direct inspection of formal expressions. Our study showed that chiral symmetry is relevant only for double pion photo production. In particular, chiral symmetry does not influence the pion cloud contribution to the electromagnetic nucleon form factor, at least within the one loop approximation considered. These results pave the way for more comprehensive studies of the role of chiral symmetry in non perturbative approaches, such as the Skyrme model

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4

Pupin, Joel César. "Simetria quiral: fótons, píons e núcleons /." São Paulo, 1994. http://hdl.handle.net/11449/132669.

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Orientador: Manoel Roberto Robilotta<br>Banca: Fernando Silveira Navarro<br>Banca: Bruto Max Pimentel Escobar<br>Resumo: Este trabalho consiste no estudo do papel das simetrias quiral e de calibre eletromagnético, da constante 'g IND. A' e do tipo de acoplamento pion-núcleon em três processos: fotoprodução de um píon e de dois píons e interação fóton-núcleon. Os dois primeiros processos são tratados na aproximação em árvore, enquanto que no último são considerados também diagramas envolvendo um loop. O papel das simetrias é analisado investigando-se a existência de relações entre os vários diagramas de um dado processo. Já o papel do tipo de acoplamento pion-núcleon é analisado, comparando-se os resultados obtidos por meio de dois modelos de implementação da simetria quiral: o sigma linear e o não linear de Weinberg. Analogamente, o papel de 'g IND. A' é avaliado pela inspeção direta das expressões obtidas para os vários processos. Este estudo mostrou que, apenas no processo envolvendo dois píons externos a simetria quiral é relevante. Em particular, a simetria quiral é irrelevante para o fator de forma eletromagnético devido à nuvem piônica do núcleon, pelo menos no contexto das correções de um loop consideradas. Estes resultados constituem pontos de partida para o estudo mais abrangente do papel da simetria quiral em abordagens não perturbativas, tais como a do modelo de Skyrme<br>Abstract: In this Work we study the role played by chiral and electromagnetic gauge symmetries, the weak constant 'g IND. A' and pion-nucleon couplings in three processes; single and double pion photo production and photon-nucleon interaction. The first two of them are treated at tree levei, whereas the last one includes one loop corrections. The role of the symmetries is analyzed considering the existence of relationships among various diagrams contributing to a given process. The influence of the way pions couple to nucleons is studied by comparing results obtained by means of the linear sigma model and the non linear model proposed by Weinberg. Finally, the role of 'g IND. A' is assessed by direct inspection of formal expressions. Our study showed that chiral symmetry is relevant only for double pion photo production. In particular, chiral symmetry does not influence the pion cloud contribution to the electromagnetic nucleon form factor, at least within the one loop approximation considered. These results pave the way for more comprehensive studies of the role of chiral symmetry in non perturbative approaches, such as the Skyrme model<br>Mestre

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5

Manzoni, Luiz ALberto. "Simetria quiral, modelos de quarks e espalhamento píon-píon no formalismo fock-tani /." São Paulo, 1995. http://hdl.handle.net/11449/132721.

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Orientador: Gastão Inácio Krein<br>Banca: Vicente Pleitez<br>Banca: Manoel Roberto Robilotta<br>Resumo: Consideramos modelos de quarks quirais para estudar o espalhamento 'PI-PI' a baixas energias. A quebra dinâmica da simetria quiral é estudada através do método variacional de Bogoliubov-Valatin. Dentro deste esquema, a estrutura de quarks dos pions considerados como bosons de Goldstone é obtida. Através do formalismo Fock-Tani obtemos um Hamiltoniano efetivo em termos dos graus de liberdade piônicos e a partir deste obtemos a amplitude de espalhamento 'PI-PI' no limiar. Usando a propriedade de "crossing" da matriz de espalhamento, o resultado é estendido para energias além do limiar. O resultado concorda com aquele obtido por Weinberg no contexto da álgebra de correntes<br>Abstract: We consider chiral quark models to study 'PI-PI' scattering at low energies. The dynamical chiral symmetry breaking is studied by means of the Bogoliubov-Valatin variational method. Within such a scheme, the quark structure of the pions considered as Goldstone bosons is obtained. By means of the Fock-Tani formalism we obtain an effective Hamiltonian in terms of pion degrees of freedom and from this we obtain the 'PI-PI' scattering matrix at threshold. Using the crossing property of the scattering matrix, the result is extended to energies beyond threshold. The result agrees with the one obtained by Weinberg in context of current algebra<br>Mestre

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6

Plum, Eric. "Chirality and metamaterials." Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/301296/.

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Electromagnetic metamaterials are artificial media that derive novel properties from periodic structuring on the sub-wavelength scale. Here, the consequences of two-dimensional (2D) and three-dimensional (3D) chirality for the electromagnetic properties of metamaterials are investigated. The focus of this work is on new ways of achieving circular conversion dichroism, optical activity and negative refraction in highly symmetric structures. In the theoretical part of this work, fundamental constraints on polarization effects in planar metamaterials are established based on symmetry and energy conservation considerations. Through the experimental study of 2D chirality, I have first observed circular conversion dichroism (i) in non-chiral structures and (ii) due to 2D-chiral arrangement of non-chiral elements. (iii) I have first seen enantiomerically sensitive reflection, yielding the experimental demonstration that circular conversion dichroism results in simultaneous directional asymmetries in transmission, reflection and absorption. In particular, a tunable transmission asymmetry of up to 21 % has been observed when extrinsic 2D chirality was associated with oblique incidence onto a non-chiral meandering wire pattern. At normal incidence circular conversion dichroism was seen for non-chiral split ring elements assembled into a 2D-chiral double-periodic array. Simultaneous directional and enantiomeric asymmetries in transmission (16 %), reflection (16 %) and absorption (32 %) were observed for normal incidence onto a double-periodic array of 2D-chiral split rings. Regarding 3D chirality, I have (i) realized the first material with a negative refractive index due to chirality and (ii) observed optical activity in the first stereometamaterial. (iii) I have discovered that optical activity can be observed in non-chiral metamaterials and (iv) I have demonstrated that optical activity in such structures is tunable and occurs in transmission and reflection. In particular polarization rotation reaching 81± and circular dichroism of up to 26 dB have been observed for non-chiral arrays of split rings, when an extrinsically 3D-chiral experimental arrangement was formed by metamaterial and direction of incidence. Based on a previously-studied meta-molecule consisting of mutually twisted metal patterns in parallel planes, microwave and photonic stereometamaterials with optical activity have been realized in this thesis and such a structure has been shown to have a negative refractive index of -1.7 for right-handed circularly polarized microwaves.

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7

Qureshi, Babar Ahmed. "Symmetries in noncommutative physics." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2008. http://wwwlib.umi.com/cr/syr/main.

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8

Dorjkhaidav, Orlokh Stone Sheldon. "Upper limit for electron-positron decaying to neutral Lambda(baryon)-antineutral Lamba(baryon) cross section and R in the center-of-mass energy range from 11.230 to 11.382 GeV." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2004. http://wwwlib.umi.com/cr/syr/main.

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9

Nasri, Salah Schechter Joseph. "Neutrinos in particle physics and cosmology." Related Electronic Resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2003. http://wwwlib.umi.com/cr/syr/main.

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10

Mudau, Lufuno Julia. "Emission of ³He ⁴He and ⁶He particles produce from the interaction of ¹²C with ⁹³Nb at 400 MeV incident energy." Thesis, University of the Western Cape, 2005. http://hdl.handle.net/11394/1903.

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Magister Scientiae - MSc<br>The inclusive double di®erential cross sections of 3He, 4He, and 6He par- ticles produced from the interaction of 12C with 93Nb at 400 MeV incident energy were extracted from the prescaled singles spectra which were mea- sured in conjunction with the correlation between 8Be fragments and ® par- ticles. A further aim of this project was to test the detector e±ciencies and energy calibrations by comparing the alpha and 8Be prescaled singles data with existing inclusive cross sections of the same reaction. The absolute cross sections of 3He and 6He fragments have been extracted based on the absolute normalization of the alpha particle spectra. A study of the inclusive spectra of 3He and 6He suggest similar features to those seen in the alpha particle spectra. These features are described by the projectile break-up and nucleon coalescence mechanisms. A theoretical model which takes both these mech- anisms into account was applied to describe 3He and 6He fragments. The model is able to reproduce reasonably well the inclusive energy spectra of the 3He and 6He fragments. These results are found to be consistent with previous studies of the emission of intermediate mass fragments.<br>South Africa

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11

Ellenburg, Michael Glen. "Massless particles in a class of field theories." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/28022.

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12

Walston, Sean Eric. "Heavy flavor decays of the Z⁰ and a search for flavor changing neutral currents /." wwwlib.umi.com/cr/uoregon/fullcit?p3136452 view abstract or download file of text, 2004.

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Thesis (Ph. D.)--University of Oregon, 2004.<br>Typescript. Includes vita and abstract. Includes bibliographical references (leaves 254-261). Also available for download via the World Wide Web; free to University of Oregon users.

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13

Bissey, François René Pierre. "Structure functions in the three nucleon system /." Title page, contents and abstract only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phb6228.pdf.

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14

Kolb, Jeffrey A. "A search for neutrinoless tau decays to three leptons /." Connect to title online (Scholars' Bank) Connect to title online (ProQuest), 2008. http://hdl.handle.net/1794/8333.

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Thesis (Ph. D.)--University of Oregon, 2008.<br>Typescript. Includes vita and abstract. Includes bibliographical references (leaves 136-140). Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.

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15

Eggers, Hans Christoph. "Intermittency, moments and correlations in distributions of particles created in high-energy collisions." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185422.

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Intermittency, as introduced into multiparticle production by Bialas and Peschanski, has become a fruitful and rapidly growing industry. The original concept of intermittency in the form of the Alpha model is discussed in detail and suggestions for extensions are made. We analyze the factorial moments measured by different experimental collaborations in terms of their nontrivial many-particle correlations, the cumulants. A large fraction of measured moments is shown to originate in two-particle correlations. The validity of the Linked Pair ansatz is tested and found to be acceptable to fourth order for hadronic collisions but uncertain for nuclear collisions. A cumulant decomposition for bin-bin correlations is derived, and a general formalism is developed for treating correlations of particle distributions consisting of several distinct populations, such as particles of different charge.

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16

Barros, Cristian Javier Caniu. "Alpha Particles in Effective Field Theory." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-13012015-131131/.

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In this thesis we work on the problem of the two-alpha-particle system using a halo/- cluster effective field theory (EFT). Our goal is to address the alpha-alpha scattering observables and its low-energy resonance identified as the ground state of Beryllium-8. In this work we start with an EFT in which the degrees of freedom are the alpha particles interacting via momentum-dependent contact forces. These, in contrast to forces that are energy-dependent, are more useful in extending the theory to systems with more than two alpha particles. Additionally, momentum-dependent forces allow us to address causal restrictions on scattering observables, known as the Wigners causality bound. We present our EFT calculations for the alpha-alpha system.<br>Nesta tese, nós trabalhamos sobre o problema do sistema de duas partículas alfa utilizando uma teoria de campos efetiva. O nosso objetivo é abordar os observáveis e a ressonância do sistema alfa-alfa de baixa energia identificada como o estado fundamental do berílio-8. Neste trabalho nós começamos com uma teoria de campo efetiva em que os graus de liberdade são as partículas alfa interagindo via forças de contato dependentes do momento. Estes, em contraste com as forças que são dependentes da energia, são mais úteis na extensão da teorias para sistemas com mais de duas partículas alfa. Além disso, forças dependentes do momento nos permitem abordar restrições causais nos observáveis, conhecidas como causalidade de Wigner. Nós apresentamos nossos cálculos para o sistema alfa-alfa.

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17

Karamov, Sergey Alexandrovich Catterall Simon. "Supersymmetric theories on the lattice." Related Electronic Resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2003. http://wwwlib.umi.com/cr/syr/main.

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18

Emam, Waled S. Souder Paul. "A search for new physics at the TeV scale via a precise measurement of the weak mixing angle in Moller scattering." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2004. http://wwwlib.umi.com/cr/syr/main.

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19

Kurkcuoglu, Seckin Balachandran A. P. "Explorations in fuzzy physics and non-commutative geometry." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2004. http://wwwlib.umi.com/cr/syr/main.

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20

Tonguc, Baris Tamer Souder Paul A. "A measurement of parity-violating asymmetry with polarized electrons scattered from protons and implications for strange form factors." Related Electronic Resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2003. http://wwwlib.umi.com/cr/syr/main.

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21

Younus, Imran Souder Paul. "First observation of the parity violating asymmetry in Moller scattering." Related Electronic Resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2003. http://wwwlib.umi.com/cr/syr/main.

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22

Muramatsu, Hajime Skwarnicki Tomasz. "Photon spectroscopy of heavy quarkonia." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2004. http://wwwlib.umi.com/cr/syr/main.

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23

Cabrera, Palmer Belkis. "Supertubes, black strings and D-brane systems." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2005. http://wwwlib.umi.com/cr/syr/main.

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24

Butt, Jamila Bashir. "First Observation of psi(3770) decays to photon chi(cJ)." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2006. http://proquest.umi.com/login?COPT=REJTPTU0NWQmSU5UPTAmVkVSPTI=&clientId=3739.

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25

Zhang, Hongshan (Kevin). "First measurements of the exclusive decays of the upsilon(5S) to B* meson B* bar meson pion pion final states and improved B*(s) meson mass measurements." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2006. http://proquest.umi.com/login?COPT=REJTPTU0NWQmSU5UPTAmVkVSPTI=&clientId=3739.

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26

Whittal, David Mark. "Quasifree knockout of charged particles from ⁴He with 100 MeV protons." Doctoral thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/17248.

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Bibliography p. 214-226.<br>Exclusive measurements have been made of the reactions ⁴He(p,2p ), (p,pd), (p,pt) and (p,ph) at 100 MeV. The primary protons were measured at two angles, 45° and 60°, in coincidence with secondary protons, deuterons, tritons or helions covering a wide range of angles on the opposite side of the beam, from -15° to -90° in plane, and from 0° to 30° out-of-plane. The purpose of the experiment was to explore the validity of the Distorted Wave Impulse Approximation (DWIA) as a description of these quasifree knockout reactions, at all geometries where the knockout cross section is significant. Six particle telescopes, each consisting of two silicon detectors and a NaI detector, were used to measure the coincident particles. The experimental data are presented in the form of energy-sharing distributions, which were generated by projecting the two-dimensional quasifree knockout loci onto the energy axis of the primary proton. The comparison between these energy-sharing distributions and the curves calculated by means of the DWIA is satisfactory for all geometries, except at the most forward secondary angles for the (p,pt) and (p,ph) reactions. It is concluded that the DWIA is an adequate formalism for modelling the quasifree knockout reactions induced by 100 MeV protons on ⁴He. Based on this conclusion, the total contribution of quasifree knockout to the existing inclusive (p,p') spectra has been calculated by integrating the DWIA cross sections over the solid angles of the secondary particles. The spectroscopic factors used were those extracted from the coincidence data. For the (p,pn) reaction, it was assumed that the spectroscopic factors were the same as for (p,2p). It is found that 70 ± 10% of the inclusive continuum yields is attributable to quasifree scattering, with ~30% arising from multiple scattering. At low energies of the scattered proton, the knockout of nucleons constitutes over 90% of the quasifree component, whereas at high energies the knockout of deuterons, tritons and helions dominates the yield. Thus the absence of discernable quasifree peaks in the inclusive spectra is probably due to the cluster knockout contributions filling in the yield at higher energies.

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27

Nisar, Shabana. "Branching fraction measurements and SU(3) diagrammatic analysis of Cabibbo-suppressed D meson decays." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2007. http://wwwlib.umi.com/cr/syr/main.

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28

Dujmić, Denis. "Open charm production at HERA-B." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3036594.

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29

Frederiksen, Joorgen Segerlund. "Theoretical studies in high energy physics and atmospheric dynamics /." Title page, introduction and contents only, 1987. http://web4.library.adelaide.edu.au/theses/09SD/09sdf852.pdf.

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30

Ryan, Daniel Edward. "Direct searches for scalar leptoquarks at the Run II Tevatron /." Thesis, Connect to Dissertations & Theses @ Tufts University, 2004.

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Thesis (Ph.D.)--Tufts University, 2004.<br>Adviser: Krzysztof Sliwa. Submitted to the Dept. of Physics. Includes bibliographical references (leaves 131-138). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

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31

Thompson, David Ian. "Low energy consequences of some non-standard Higgs models." Connect to e-thesis, 2007. http://theses.gla.ac.uk/143/.

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Thesis (Ph.D.) - University of Glasgow, 2007.<br>Ph.D. thesis submitted to the Department of Physics and Astronomy, Faculty of Physical Sciences, University of Glasgow, 2007. Includes bibliographical references. Print version also available.

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32

Miletic, Tatjana Lane C. E. "Search for the disappearance of a neutron with KamLAND detector /." Philadelphia, Pa. : Drexel University, 2009. http://hdl.handle.net/1860/3129.

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33

Oo, U. Ne. "A chiral symmetric calculation of pion-nucleon scattering /." Title page, table of contents and abstract only, 1993. http://web4.library.adelaide.edu.au/theses/09PH/09pho59.pdf.

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34

Li, Yuan. "Triaxial strongly deformed band and high spin states in 168Lu." Master's thesis, Mississippi State : Mississippi State University, 2003. http://library.msstate.edu/etd/show.asp?etd=etd-03132003-141252.

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35

Patel, Sunil. "A study of heavy quark production and semi-leptonic decay in deep-inelastic ep scattering at high energies." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670155.

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36

Striley, David L. "Large transverse momentum [pi]⁰ meson production by 0.5 TeV/c p, [pi]+ and K+ incident on beryllium /." free to MU campus, to others for purchase, 1996. http://wwwlib.umi.com/cr/mo/fullcit?p9737874.

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37

Torres, Sergio. "Observation of K* (2060) in the [phi]K[pi] final state produced in proton-nuclei interactions at 400 GeV/c." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/49943.

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In 1982 Fermilab experiment E623 took data in a search for high-mass boson resonances which decay into one or two ɸ mesons produced in 400 GeV/c proton-nuclei interactions. A hardware trigger selected 3.6 million events with identified K⁺K⁻ pairs. Here I report my study of events with ɸKπ in the final state and present the first evidence for K°*(2060) decaying into ɸKπ and ɸK°*(890).<br>Ph. D.<br>incomplete_metadata

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38

Day, Francesca. "Astrophysical signatures of axion-like particles." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:215f6432-6dbb-4a16-80d8-3ad0bc76ec2d.

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The Standard Model of particle physics has enjoyed unprecedented success in predicting experimental results. However, evidence from astrophysical observations points to the existence of a dark sector of particles that interact only very weakly with the Standard Model. In this work, we search for dark sector signatures in X-ray telescope data. Much of this work concerns a class of hypothetical particles, the axion-like particle (ALP). ALPs are a theoretically well-motivated extension of the Standard Model. If ALPs exist, they may lead to intriguing astrophysical signatures: in the presence of a background magnetic field, ALPs and photons can interconvert. We could detect ALPs by searching for photon to ALP conversion. For example, photons produced by point sources in or behind galaxy clusters may convert to ALPs in the cluster's magnetic field. This could lead to observable spectral anomalies. Using this strategy, we place world leading bounds on the ALP-photon coupling. One potential signal of dark matter is an anomalous line in the spectra of galaxies and galaxy clusters. In 2014, an anomalous line was found at an energy of 3.5 keV. The nature and cause of this line is still under discussion. We analyse a scenario in which the 3.5 keV line arises from dark matter decay to ALPs, which interconvert with 3.5 keV photons in astrophysical magnetic fields. We further report an anomalous deficit at 3.5 keV in the spectrum of the Active Galactic Nucleus at the centre of the Perseus galaxy cluster. This motivates the study of a new model in which both features are caused by âfluorescent dark matterâ which resonantly interacts with 3.5 keV photons. We analyse observations of Perseus at 3.5 keV to date, and show that they are well explained by this model. Further theoretical and experimental work is needed to discover or exclude fundamental physics effects in X-ray spectra.

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Pais, Preema R. "Reducing background in the t neutrino mass limiting decay t [plus or minus] --> K [plus or minus] Ks̳p0̳̳vt̳ /." Connect to online version, 2006. http://ada.mtholyoke.edu/setr/websrc/pdfs/www/2006/174.pdf.

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Porcelli, Tracy Ann. "Measurements of muon catalyzed dt fusion in solid HD." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ37360.pdf.

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Lepeintre, François. "Supersymmetric models of flavor /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/9699.

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Gammal, Arnaldo. "O Termo Sigma Nuclear no Modelo de Skyrme." Universidade de São Paulo, 1997. http://www.teses.usp.br/teses/disponiveis/43/43132/tde-04122013-164120/.

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O termo sigma nuclear (o conteúdo isoescalar de quarks do estado nuclear) é calculado no contexto do modelo de Skyrme, através da consideração da dependência do potencial núcleon-núcleon com as massas de corrente. O termo sigma nuclear é extraído da massa nuclear usando-se o teorema de Hellmann-Feynman, derivando a interação núcleon-núcleon com respeito às massas dos quarks up e down, m IND.q V IND.NN/ m IND.q. O potencial é construído na aproximação do ansatz produto quantizado no modelo de Skyrme. A dependência às massas dos quarks vem do termo relativo a massa do píon na Lagrangiana de Skyrme. Esta conexão é feita usando a relação de Gell-Mann, Oakes e Renner. É feita uma discussão de como m IND. m IND.q V IND.NN/ m IND.q deve entrar no cálculo do termo sigma nuclear no contexto da mecânica quântica não relativística. Também calculamos o termo sigma do núcleon e as derivadas das constantes de acoplamento píon-núcleon, carga axial, raios eletromagnéticos e momentos magnéticos. Considerando a contribuição do potencial para o termo sigma da matéria nuclear, o valor local do condensado de quarks é estimado. Devido ao caráter repulsivo do termo do potencial, o condensado diminui somente 5% na densidade normal. O problema da falta de repulsão na magnitude da parte real do potencial ótico isoescalar píon-núcleo-onda-s, provenientes da análise de dados de espalhamento e átomos piônicos, é resolvido no contexto presente. A contribuição do potencial skyrmion-skyrmion ao termo sigma nuclear, proporciona a repulsão necessária para o potencial píon-núcleo, em um surpreendente acordo com os parâmetros ajustados e também com a sua dependência da massa nuclear.<br>The nuclear sigma term, the isoscalar quark content of the nuclear state, is calculated within the Skyrme model considering the current quark mass dependence of the nucleon-nucleon potential. The nuclear sigma term is extracted from the nuclear mass using the Hellmann-Feynman theorem, which demands for the derivative of the nucleon-nucleon interaction, m IND.q V IND.NN/ m IND.q, with respect to the up-down quark masses, The potential is evaluated in the skyrmion-skyrmion picture within the quantized product anstatz. The quark mass dependence of the potential comes from the pion mass term in the Skyrme Lagrangian. Such connection is made using the Gell-Mann, Oakes and Renner relation. We provide a discussion on how m IND.q V IND.NN/ m IND.q should enter in the evaluation of the nuclear sigma-term in the context of nonrealativistic quantum mechanics. We also calculate the nucleon sigma term, and the derivatives of the pion-nucleon coupling constant, axial charge, electromagnetic radius and magnetic moments. Considering the contribution of the potential to the nuclear matter sigma term, the local value quark condensate drops only 5% at normal density. The problem of missing repulsion in the magnitude of the real part of the isoscalar s-wave pion nucleus optical potential, as taken from pionic atom and elastic scattering data analysis, is fixed in the present context. The contribution of the skyrmion-skyrmion potential to the nuclear sigma term, provides the missing repulsion to the pion-nucleus optical potential, in remarkable agreement with the fitted parameters and also reproducing its mass dependence.

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43

Brunelli, Jose Carlos. "Renormalização na quantização estocástica de teorias de campos." Universidade de São Paulo, 1991. http://www.teses.usp.br/teses/disponiveis/43/43132/tde-26022014-144556/.

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Dentro do esquema de quantização estocástica de Parisi e Wu estudamos aspectos ligados a renormalização da teoria estocástica de certos modelos em teoria de campos. No formalismo funcional para processos estocásticos implementamos a expansão 1/N para o modelo sigma não linear e usando a identidade de Ward, devida a simetria de BRS da ação efetiva dessa formulação, mostramos a renormalizabilidade do modelo. No formalismo de Langevin para processos estocásticos estudamos a renormalizabilidade do modelo de Thirring massivo e mostramos perturbativamente o anulamento da função beta do grupo de renormalização a tempo fictício finito.<br>In the stochastic quantization scheme of Parisi and Wu we study the renormalization of the stochastic theory of some models in field theory. Following the path integral approach for stochastic process we perform the 1/ N expansion of the nonlinear sigma model and, using a Ward identity obtained, from a BRS symmetry of the effective action of this formulation, we show the renormalizability of the model. Using the Langevin approach for stochastic process we study the renormalizability of the massive Thirring model showing perturbativaly the vanishing of the renormalization group\'s beta function at finite fictitious time.

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Tilles, P. F. C. [UNESP]. "Quantização de partículas com spin." Universidade Estadual Paulista (UNESP), 2007. http://hdl.handle.net/11449/138360.

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Made available in DSpace on 2016-05-17T16:50:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-03-12. Added 1 bitstream(s) on 2016-05-17T16:54:30Z : No. of bitstreams: 1 000855913.pdf: 421119 bytes, checksum: af9ecbafa30255e17d4d849d32b01ab5 (MD5)<br>Uma partícula clássica relativística é descrita utilizando-se o formalismo de Dirac para sistemas vinculados devido à invariança sob transformações de reparametrizações requerida por uma teoria explícitamente covariante. Nós introduzimos os graus de liberdade de spin via variáveis de Grassman, que levam diretamente ao conceito de supersimetria presente na teoria. As equações de movimento e a quantização são consideradas tanto para as teorias livres de spin 0 e 1/2, como para a teoria com interação eletromagnética. A álgebra dos vínculos de primeira classe é extendida para descrever partículas de spin N/2, que incluem as representações de spin 1. A teoria quântica obtida é comparada com a teoria clássica de campos<br>Aclassical relativistic particleis described by means of Dirac's formalism for constrained systems, where the constraints come from the reparametrization invariance required by an explicitly covariant theory. We introduce spin degrees of freedom via Grassman variables, which leads directly to the concept of supersymmetry in the theory. The equations of motion and quantization are considered both for the spin 0 and 1/2 free theories, and for the eletromagnetic interaction. The ﬁrst class constraints algebra is extended to describe spin N/2 particles, which include spin 1 representations. The quantum theory obtained is compared to the classical theory of ﬁelds

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Tilles, Paulo Fernando Coimbra. "Quantização de partículas com spin /." São Paulo, 2007. http://hdl.handle.net/11449/138360.

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Orientador: Nathan Jacob Berkovits<br>Banca: Bruto Max Pimentel Escobar<br>Banca: Ricardo Ivan Medina Bascur<br>Resumo: Uma partícula clássica relativística é descrita utilizando-se o formalismo de Dirac para sistemas vinculados devido à invariança sob transformações de reparametrizações requerida por uma teoria explícitamente covariante. Nós introduzimos os graus de liberdade de spin via variáveis de Grassman, que levam diretamente ao conceito de supersimetria presente na teoria. As equações de movimento e a quantização são consideradas tanto para as teorias livres de spin 0 e 1/2, como para a teoria com interação eletromagnética. A álgebra dos vínculos de primeira classe é extendida para descrever partículas de spin N/2, que incluem as representações de spin 1. A teoria quântica obtida é comparada com a teoria clássica de campos<br>Abstract: Aclassical relativistic particleis described by means of Dirac's formalism for constrained systems, where the constraints come from the reparametrization invariance required by an explicitly covariant theory. We introduce spin degrees of freedom via Grassman variables, which leads directly to the concept of supersymmetry in the theory. The equations of motion and quantization are considered both for the spin 0 and 1/2 free theories, and for the eletromagnetic interaction. The ﬁrst class constraints algebra is extended to describe spin N/2 particles, which include spin 1 representations. The quantum theory obtained is compared to the classical theory of ﬁelds<br>Mestre

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46

Kvasnikova, Ioulia. "Mesonic sources of dileptons in ultrarelativistic nuclear collisions." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37753.

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In this work thermal dilepton production from a hot medium created in heavy ion collision is studied. Using an effective Lagrangian technique for particle decays and annihilations, a complete method for calculation of the lepton pair production rate is developed. The importance of axial vector meson contributions to the dilepton spectrum is analyzed. Different effective Lagrangians for the a1rhopi interaction are considered, and a new form of b1o(&phis;)pi effective Lagrangian is introduced.<br>A systematic study of light meson contributions is performed. The most significant decay and reaction contributions are calculated and summed for low and intermediate invariant mass dileptons. The calculated dilepton rate is compared to that obtained using spectral functions extracted from data, and it is shown that the chosen set of mesonic reactions and decays accounts for all significant contributions to the thermal dilepton emission.<br>A hydrodynamic approach to the space-time evolution of the hot medium formed as a result of a central heavy ion collision at ultra-relativistic energies is considered. A theoretical curve of intermediate invariant mass dilepton spectrum is computed and compared to the NA50 data from central Pb(158 AGeV)+Pb collisions. Experimental acceptance cuts are accounted for. Drell-Yan processes are considered as well. We find that our thermal dileptons account for the intermediate mass excess observed by the NA50 Collaboration. We see no need to invoke charm enhancement. Predictions for the future experiments at RHIC and are made.

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47

Jin, Daming. "Off line computer analysis of total cross section for proton nucleus collisions at 400 Gev/C proton beam energy on a VAX system and conversion to a Z-386 PC system." Virtual Press, 1991. http://liblink.bsu.edu/uhtbin/catkey/834638.

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A large MULANA based analysis package, written in FORTRAN, for computing the cross section for proton - nucleus collisions at 400 GeV/c momentum from data taken in experiment E609 at FNAL, was implemented on a Z-386, 16 MHz microcomputer workstation featuring an 80 Mbyte hard drive, and a three Gbyte 8-mm Exebyte tape drive, based in the Ball State High Energy Physics Laboratory, in a feasibility study of conducting such analysis on a workstation as a viable alternative and/or adjunct to the Ball State University VAX system. One of 40 large 1600 bpi 9-track data tapes from Experiment 609 provided the data file for the computation. The analysis package was first run on the VAX system. Special problems solved in connection with using the software package included converting the large data file to a suitable form for use at the workstation, transporting that file from the VAX to the workstation, modifying the VAX FORTRAN software package for implementation in the OS/2 workstation operating system environment, and graphical exposition of the results. With the results of conducting the analysis on the VAX system serving as a benchmark, it was determined first that the quantitative analysis results were identical, second, that computing times were similar, and third that the workstation provided unique conveniences. Overall, the results showed that the workstation is a reasonable alternative to using the VAX for High Energy Physics analysis work but also suggest the attractiveness of using similar but faster workstations in the near future.<br>Department of Physics and Astronomy

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Alton, Andrew K. "Evidence for the existence of jets in photon-parton interaction events at center of mass energies from 18 to 28 GEV." Virtual Press, 1995. http://liblink.bsu.edu/uhtbin/catkey/1014850.

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Experiment E683 at Fermi National Accelerator Laboratory (FNAL) in Batavia, Illinois, uses a modular, high-energy sampling calorimeter as the basis of the detector system. This detector provides information on the energy and position of particles that exit a collision of a photon or pion with a target proton. While exiting particles are thought to form what are described as "jets", and several E683 projects involve working with these jets, it has not yet been demonstrated that jets indeed have been detected.The solution proposed here involves demonstrating that E683 data has a statistically significant "jettiness" even in a data sample which has not been biased. Towards this, a data sample was selected based on criteria unrelated to the presumption of jets. Planarity and the Et Flow were chosen as measures of how oblong(jetlike) an event is. The sample was then examined for planarity and Et flow in a number of kinematic ranges and the results demonstrate that over a certain kinematic range, events in our sample are increasingly planar, as we hypothesized.<br>Department of Physics and Astronomy

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Hosack, Michael G. "Optimization of particle tracking for experiment E683 at Fermi National Laboratory." Virtual Press, 1995. http://liblink.bsu.edu/uhtbin/catkey/941370.

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The subject of this thesis is the improvement of particle tracking through the identification and correction of small systematic errors in particle "hit" locations due to positioning of tracking detectors. These errors call be as large or larger than the statistical spatial resolution of tracking detectors themselves, and therefore must be corrected. The focus is on identification and correction of errors due to rotations and beam axis translations.An algorithm is developed for use with proportional wire chamber and drift chamber detectors in experiment E683 at the Wideband facility of Fermi National Laboratory. In this experiment, high energy (tens of GeV) particles, primarily mesons, were produced when photons with energies of 40-400 GeV struck a metal or liquid target.At the present time, the method and code developed for this thesis has not been applied to real data, although an analysis of its effectiveness as a function of detector resolution has been investigated with Monte-Carlo simulations.<br>Department of Physics and Astronomy

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De, Felice Antonio. "The accelerating universe and other cosmological aspects of modified gravity models." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2005. http://wwwlib.umi.com/cr/syr/main.

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