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1
Matheson, A. "Chiral symmetry breaking." Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234997.
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Hewson, Paul Joseph. "Chiral symmetry in nucleons." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/chiral-symmetry-in-nucleons(bc2c5e94-1830-465e-b10c-5b7c162e7381).html.
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Chiral perturbation theory allows us to probe the low energy properties of hadrons. In this thesis we have looked at the axial coupling constant (see chapter 4) and baryon number violation (see chapter 5).We calculated the axial coupling constant up to O(p^4) using the extended on mass shell renormalisation scheme in chiral perturbation theory. We also included the decuplet as an explicit degree of freedom. To fit the free parameters in our expression we used a combination of lattice and experimental data. We found that the fourth order corrections were quite large, and we struggled to produce an acceptable fit to the data. We also saw that the running of g_{A}^{pn} with M_\pi predicted by lattice QCD and ChPT at O(p^4) do not agree well. This is likely due to a combination of finite size effects impacting the low pion mass lattice data and the chiral perturbative series converging slowly. For our work on baryon number violation we looked at determining the values of two low-energy constants that appear in the baryon violating chiral Lagrangian. To do this, we matched our expression to lattice data. Previous determinations of the parameters had been done without calculating the effect of loops, ours was the first investigation to see what impact the loop diagrams would have. We found that our determinations of the parameters were in agreement with previous results, suggesting the effect of the loops is small. We also performed a chiral extrapolation, and found that our results were in agreement with previous results that did not account for loop corrections. This suggests that the impact of higher-order corrections is not significant for this baryon-number-violating process.
3
Sharan, Ujjawal. "Topology and chiral symmetry breaking in QCD." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302137.
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Gebauer, Astrid. "Chiral symmetry breaking transitions in holographic duals." Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/206257/.
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Generalisations of the AdS/CFT Correspondence are used to study chiral symmetry breaking in dual gauge theories. We use the D3/D7 and D3/D5 systems to model both 3+1 and 2+1 dimensional, strongly coupled, gauge theories with quark fields. We show that chiral symmetry breaking is induced by either an imposed running coupling/dilaton profile or a background magnetic field. We explore the low energy effective theory of the pions of these models deriving simple integral equations for low energy parameters in the spirit of constituent quark model results. We also explore the phase structure of these models, with respect to temperature, chemical potential and applied electric field. The phase diagrams contain regions with broken and restored chiral symmetry separated by first order, second order and BKT transitions. There is an extra transition associated with the melting of the meson states into the background plasma. Finally we use the phenomenological dilaton profile to engineer holographic descriptions of theories with QCD-like phase diagrams.
5
Smith, John Warren. "Dynamical chiral symmetry breaking in four-fermi theories." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30345.
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Dynamical symmetry breaking of discrete chiral symmetry in four-fermi models is studied. A variational method is used to determine the effective potential. This potential is then examined to determine the critical coupling for which a phase transistion between massless and massive states occurs. Two trial ground states are used in the variational calculation and the results are the same in each case. The first is the ground state of a free massive fermion and the other is a generalized Bogoliobov-Valatin transformation of a free massless fermion ground state. In each case dynamical symmetry breaking occurs, if the coupling is fine-tuned. The results are shown to be valid for physical dimensions 1+1, 2+1 and 3+1 and compared with those of other variational methods and the 1/N expansion.Science, Faculty of
Physics and Astronomy, Department of
Graduate
6
Cundy, Nigel. "Instantons, topology, and chiral symmetry breaking in QCD." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275509.
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Klein, Kreisler Martin. "Chiral symmetry restoration in finite temperature QEDâ†3." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316877.
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Ashworth, Richard Michael. "Quantum field theories having conformal and chiral symmetry." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292952.
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Ouellette, Stephen M. "SU(3) chiral symmetry in non-relativistic field theory." Diss., Pasadena, Calif. : California Institute of Technology, 2001. http://resolver.caltech.edu/CaltechETD:etd-08172001-054126.
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Shcheredin, Stanislav. "Simulations of lattice fermions with chiral symmetry in quantum chromodynamics." Doctoral thesis, [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=97410907X.
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Liu, Zhaofeng. "Hadron properties from lattice QCD simulations with exact chiral symmetry." Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3219010.
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Sekihara, Takayasu. "Strong interactions in antikaon-nuclear systems based on chiral symmetry." 京都大学 (Kyoto University), 2011. http://hdl.handle.net/2433/142372.
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Kokulu, Ahmet. "Eta-eta Prime Mixing In Chiral Perturbation Theory." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12609808/index.pdf.
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Quantum Chromodynamics (QCD) is believed to be the theory of strong
interactions. At high energies, it has been successfully applied to explain
the interactions in accelerators. At these energies, the method used to do
the calculations is perturbation theory. But at low energies, since the
strong coupling constant becomes large, perturbation theory is no longer
applicable. Hence, one needs non-perturbative approaches. Some of these
approaches are based on the fundamental QCD Lagrangian, such as the QCD sum
rules or lattice calculations. Some others use an effective theory approach
to relate experimental observables one to the other. Chiral Perturbation
Theory (ChPT) is one of these approaches. In this thesis, we make a review of chiral
perturbation theory and its applications to study the mixing phenomenon
between the neutral pseudoscalar mesons eta and eta-prime.
14
Hoffmann, Roland. "Chiral properties of dynamical Wilson fermions." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2005. http://dx.doi.org/10.18452/15341.
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Quantenchromodynamik mit zwei leichten Quarks wird in der Gitterregularisierung mit verbesserten Wilson Fermionen betrachtet. Die chirale Symmetrie in dieser Formulierung wird von Gitterartefakten, die linear im Gitterabstand a sind, explizit gebrochen. Daher erfordern die axialen Isospin Ströme Verbesserung (im Symanzik Sinn), sowie eine endliche Renormierung, wenn sie die Ward--Takahashi Identitäten des Kontinuums bis auf kleine Gitterkorrekturen proportional zu a^2 erfüllen sollen. Algorithmische Probleme bei großen Gitterabständen machen die numerischen Simulationen der Gittertheorie schwierig. Der Hybrid Monte Carlo Algorithmus leidet unter einem verformten Dirac Spektrum in Form unphysikalisch kleiner Eigenwerte. Es wird gezeigt, daß dies ein Gitterartefakt ist, welches schnell verschwindet, wenn der Gitterabstand verringert wird. Ein alternativer Algorithmus, der polynomische Hybrid Monte Carlo Algorithmus, zeigt erheblich bessere Eigenschaften im Umgang mit den außergewöhnlich kleinen Eigenwerten. Durch Erweiterung und Verbesserung vorher verwendeter Methoden wird die nicht-perturbative Verbesserung und Renormierung des Axialstroms durch Korrelationsfunktionen im Schrödinger Funktional implementiert. In beiden Fällen wird dies erzielt, indem man Ward Identitäten des Kontinuums bei endlichem Gitterabstand erzwingt. Zusammen stellt dies die chirale Symmetrie bis zur quadratischen Ordnung im Gitterabstand wieder her. Mit wenig zusätzlichem Aufwand wird auch der Normierungsfaktor des lokalen Vektorstroms berechnet. Die Methoden, die hier entwickelt und implementiert wurden, können leicht auch für andere Wirkungen verwendet werden, die im Schrödinger Funktional formuliert werden können. Dies umfaßt verbesserte Eichwirkungen sowie Theorien mit mehr als zwei dynamischen Quarks.Quantum Chromodynamics with two light quark flavors is considered in the lattice regularization with improved Wilson fermions. In this formulation chiral symmetry is explicitly broken by cutoff effects linear in the lattice spacing a. As a consequence the isovector axial currents require improvement (in the Symanzik sense) as well as a finite renormalization if they are to satisfy the continuum Ward-Takahashi identities associated with the isovector chiral symmetries up to small lattice corrections of order a^2. In exploratory numerical simulations of the lattice theory algorithmic difficulties were encountered at coarse lattice spacings. There the hybrid Monte Carlo algorithm used suffers from a distorted Dirac spectrum in the form of unphysically small eigenvalues. This is shown to be a cutoff effect, which disappears rapidly as the lattice spacing is decreased. An alternative algorithm, the polynomial hybrid Monte Carlo algorithm, is found to perform significantly better in the presence of exceptionally small eigenvalues. Extending previously used methods both the improvement and the renormalization of the axial current are implemented non-perturbatively in terms of correlation functions formulated in the framework of the Schrödinger functional. In both cases this is achieved by enforcing continuum Ward identities at finite lattice spacing. Together, this restores the isovector chiral symmetry to quadratic order in the lattice spacing. With little additional effort the normalization factor of the local vector current is also obtained. The methods developed and implemented here can easily be applied to other actions formulated in the Schrödinger functional framework. This includes improved gauge actions as well as theories with more than two dynamical quark flavors.
15
Clunas, Scott. "The synthesis of chiral Câ†3-symmetric systems." Thesis, University of Aberdeen, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310643.
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Chapter one is an overall introduction reviewing the applications of compounds possessing rotational symmetry, in particular their role as asymmetric reagents/catalysts in various reactions. The attempted syntheses of two different types of C3-symmetric homochiral triols are described in chapter two. Unfunctionalised and functionalised triamides were synthesised from the corresponding amine and 1,3,5-benzenetricarbonyl trichloride. Unfunctionalised N-substituted 1,3,5-triazacychlohexanes (triazines) were synthesised from the corresponding amine and formaldehyde, however reactions between chiral amino alcohols and formaldehyde failed to give the desired trihydroxy triazines. Chapter three describes the syntheses of a range of unfunctionalised chiral C3-symmetric compounds, as well as a review of C3-symmetric systems as host molecules. The successful synthesis of a range of unfunctionalised triethrs was carried out by reacting 1,3,5-tris(bromomehyl)mesitylene with some selected terpenes and other alcohols. Their role as host molecules was investigated, however they failed to bind with any of the various metals that were used. Their asymmetric induction capabilities were also tested when one of the triethers was used as a catalyst in the Et2Zn/aldehyde reaction. The desired alcohol was indeed isolated, however it was found by 1H nmr of the Mosher's ester to be a reacemic mixture. In chapter four the synthesis of the unfunctionalised triethers that was described in chapter three was extended to the synthesis of C3-symmetric triethers containing functional groups. A range of tridentate ligands were synthesised containing either amino, ester, keto or hydroxyl terminal groups. In addition to these, trihydroxy ligands containing amino linkages in place of ethereal linkages were also synthesised. From these compounds three of the trihydroxy ligands were used in complexation reactions with Sn, Ti, Si, Ni, and Cu. The reactions using Si, Ni and Cu failed to give the desired complexes. However, strong evidence was obtained for the existence of the desired Sn and Ti complexes. Once again using the Et2Zn/aldehyde reaction preliminary asymmetric induction studies were carried out using one of the Ti complexes. The reaction showed some selectivity in favour of the R enantiomer. Chapter four also describes the syntheses of some hexadentate ligands, in particular the synthesis of a chiral C3-symmetric hexol, a C3-symmetric ligand containing three β keto-ester groups, and also a 1,3-diketo derivative.
16
Black, Deirdre, Masayasu Harada, and Joseph Schechter. "Chiral Approach to φ radiative decays." American Institite of Physics, 2007. http://hdl.handle.net/2237/11986.
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Almiron, Núria. "Chiral symmetry breaking and pattern selection in chemical and biological systems." Doctoral thesis, Universite Libre de Bruxelles, 1988. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/213330.
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Wright, Stewart Victor. "Chiral symmetry and the extraction of hadron properties from lattice QCD." Title page, abstract and contents only, 2001. http://web4.library.adelaide.edu.au/theses/09PH/09phw953.pdf.
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"December 2001." Author's previously published articles appended. Bibliography: leaves 138-147. Describes a method of extrapolating from the heavy quark regime, where lattice caculations now occur, to physical quark masses, which carefully incorporates key model independent constraints, especially those imposed by chiral symmetry. This extrapolation method allows the extraction, not only of physical hadron masses with high accuracy, but also the of other properties, including the pion-nucleon sigma term and the J parameter for the vector mesons.
19
Ramos, Elena Garcia. "Investigations of chiral symmetry breaking and topological aspects of lattice QCD." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2014. http://dx.doi.org/10.18452/16890.
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Die spontane Brechung der chiralen Symmetrie ist ein faszinierendes Phenomän der QCD mit fundamentalen phänomenologischen Implikationen. Die Brechung der chiral Symmetrie ist beispielsweise verantwortlich für die niedrige Masse der Pionen, welche die effektiven Goldstone Boson der spontan gebrochene Symmetrie sind. Die spontane Brechung der chiral Symmetrie und die chirale Anomalie sind niedrig Energie-Phenomäne der QCD, weshalb nichtperturbative Methoden nötig sind um sie zu studieren. In der vorliegenden Arbeit verwenden wir die Gitterregularisierung der QCD, um das chirale Kondensat, den Ordnungsparameter der spontanen Brechung der chiralen Symmetrie zu bestimen. Dazu wendeten wir die Definition der in dieser Arbeit studierten Observablen über Dichteketten an, die eine theoretisch wohldefinierte Bahndlung der Observablen zulässt. Für die praktische Berechnung wurde die kürzlich entwickelte Methode der spektralen Projektoren angewandt. In dieser Weise berchnen wir den Kontinuumlimes des chiralen Kondensates, das im chiralen Limes gewonnen, sowohl für N_f=2 als auch für N_f=2+1+1 Flavour von so genannten twisted mass Fermionen. Des Weiteren untersuchen wir das chirale Verhalten der topologischen Suszeptibilität. Wir verwenden hier wieder die Methode der spektralen Projektoren, anstelle aufwendigerer Verfahren, die chirale Symmetrie erhalten, aber zu numerisch sehr aufwändigen Simulationen führen. Schließ lich kommentieren wir die sich aus den starken Autokorrelationen ergebenden Schwierigkeiten dieser Rechnung. Abschließ end stellen wir die Kontinuumlimes-Ergebnisse der topologischen Suszeptibilität in der rein gluonischen Theorie vor, die es uns erlauben, die Witten-Veneziano-Formel zu testen. Unseren Untersuchung zufolge ist diese Formel gut erfüllt. Diese Tatsache stützt die Gültigkeit der Formel, die die topologischen Fluktuationen der Eichfelder mit der unerwartet groß en Masse des eta'' Mesons in Verbindung setzt.The spontaneous breaking of chiral symmetry is a fascinating phenomenon of QCD whose mechanism is still not well understood and it has fundamental phenomenological implications. It is, for instance, responsible for the low mass of the pions which are effectively Goldstone bosons of the spontaneously broken symmetry. Since these phenomena belong to the low energy regime of QCD, non-perturbative techniques have to be applied in order to study them. In this work we use the twisted mass lattice QCD regularization to compute the chiral condensate, the order parameter of spontaneous chiral symmetry breaking. To this end we apply the recently introduced method of spectral projectors which allows us to perform calculations in large volumes due to its inherently low computational cost. This approach, moreover, enables a direct calculation of the chiral condensate based on a theoretically clean definition of the observable via density chains. We thus present a continuum limit determination of the chirally extrapolated condensate for N_f=2 and N_f=2+1+1 flavours of twisted mass fermions at maximal twist. In addition we study the chiral behavior of the topological susceptibility, a measure of the topological fluctuations of the gauge fields. We again apply the spectral projector method for this calculation. We comment on the difficulties which appear in the calculation of this observable due to the large autocorrelations involved. Finally we present the continuum limit result of the topological susceptibility in the pure gluonic theory which allows us to perform a test of the Witten-Veneziano relation. We found that this relation is well satisfied. Our results support the validity of the Witten-Veneziano formula which relates the topological fluctuations of the gauge fields with the unexpectedly large value of the eta''
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Wiggers, Greg A. "Molecular Design for Nonpolar Chiral-axial Quadratic Nonlinear Optics." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1220713451.
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Carignano, Stefano Verfasser], Michael [Akademischer Betreuer] Buballa, and Jochen [Akademischer Betreuer] [Wambach. "Inhomogeneous chiral symmetry breaking phases / Stefano Carignano. Betreuer: Michael Buballa ; Jochen Wambach." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2012. http://d-nb.info/1106256719/34.
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Doi, Takahiro. "Lattice QCD study for the relation between confinement and chiral symmetry breaking." 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225399.
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Carignano, Stefano [Verfasser], Michael Akademischer Betreuer] Buballa, and Jochen [Akademischer Betreuer] [Wambach. "Inhomogeneous chiral symmetry breaking phases / Stefano Carignano. Betreuer: Michael Buballa ; Jochen Wambach." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2012. http://nbn-resolving.de/urn:nbn:de:tuda-tuprints-31493.
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De, Asitkumar. "Spontaneous chiral symmetry breaking and fermion mass generation in Lattice field theories /." The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487591658176323.
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Sauerwein, Ulrich [Verfasser], Matthias [Akademischer Betreuer] Lutz, and Rob [Akademischer Betreuer] Timmermans. "Axial-Vector Currents and Chiral Symmetry / Ulrich Sauerwein ; Matthias Lutz, Rob Timmermans." Darmstadt : Universitäts- und Landesbibliothek, 2021. http://d-nb.info/123414994X/34.
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Gentles, Andrew James. "Nonperturbative propagators in axial gauge QCD." Thesis, University of Southampton, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243921.
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MANTOVANI, SARTI Valentina. "Scaled chiral quark-solitons for nuclear matter." Doctoral thesis, Università degli studi di Ferrara, 2012. http://hdl.handle.net/11392/2389448.
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One of the most challenging problems in hadronic and nuclear physics is to study
nuclear matter at finite density by using a scheme which includes one of the
fundamental properties of QCD, namely chiral symmetry.
The problem of studying nuclear matter with chiral Lagrangians is not trivial;
for instance models based on the linear σ-model fail to describe nuclear matter
already at ρ ∼ ρ0 because the normal solution in which chiral symmetry is broken
becomes unstable respect to the Lee-Wick phase. The main problems in these
models are due to the constraints on the scalar field dynamics imposed by the
Mexican hat potential [1]. The interaction terms of σ and π fields in the linear
realization of chiral symmetry allows the chiral fields to move away from the
chiral circle as the density raises and to reach, already at ρ0, the local maximum
where σv = 0 and chiral symmetry is restored.
The difficulty of a too early restoration of chiral symmetry at finite density
can be overcame in two different ways. One could implement chiral symmetry
into the Lagrangian through a non-linear realization [2] where the scalar fields are
forced to stay on the chiral circle. The other approach is still based on a linear
realization of chiral symmetry but with a new potential, which includes terms
not present in the Mexican hat potential. A possible guideline in building such a
potential is scale invariance, which is spontaneously broken in QCD due to the
presence of the parameter ΛQCD coming from the renormalization process and
it is strictly connected to a non vanishing gluon condensate. This fundamental
symmetry of QCD can be implemented in the Lagrangian at mean-field level,
following the approaches in [3, 4], through the introduction of a new scalar field,
the dilaton field, whose dynamics is regulated by a potential chosen in order to
reproduce the scale divergence of QCD.
In this work we will adopt a Chiral Dilaton Model (CDM) which also includes scale invariance introduced by the nuclear physics group of the University of
Minnesota [5–8]. It has already been shown that an hadronic model based on
this dynamics provides a good description of nuclear physics at densities about ρ0
and it describes the gradual restoration of chiral symmetry at higher densities [9].
In the same work the authors have shown a phase diagram, where the interplay
between chiral and scale invariance restoration lead to a scenario similar to that
proposed by McLerran and Pisarski in [10]. It is therefore tempting to explore
the scenario presented in [9] at a more microscopic level.
The new idea we develop in this work is to interpret the fermions as quarks,
to build the hadrons as solitonic solutions of the fields equations as in [11] and,
finally, to explore the properties of the soliton at finite density using the Wigner-
Seitz approximation.
Similar approaches to a finite density system have been investigated in the
past [12–17]. A problem of those works is that the solitonic solutions are unstable
and disappear already at moderate densities when e.g. the linear σ-model is
adopted [16]. We are therefore facing an instability similar to the one discussed
and solved when studying nuclear matter with hadronic chiral Lagrangians. The
first aim of this thesis is to check whether, just by modifying the mesons interaction
with the inclusion of scale invariance, the new logarithmic potential allows the
soliton crystal to reach higher densities. Next, since the CDM also takes into
account the presence of vector mesons, the second and more important aim is
to check whether the inclusion of vector mesons in the dynamics of the quarks
can provide saturation for chiral matter. We should remark that no calculation,
neither in vacuum nor at finite density, exists at the moment for the CDM with
quarks and vector mesons.
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Capdevilla, Roldan Rodolfo Maia [UNESP]. "Dynamical chiral symmetry breaking: the fermionic gap equation with dynamical gluon mass and confinement." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/92026.
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capdevillaroldan_rm_me_ift.pdf: 1695600 bytes, checksum: 56f8cc2724bbe924e0b430ebe1a3b24e (MD5)Alguns aspectos da quebra de simetria quiral para quarks na representação fundamental são discutidos no contexto das equações de Schwinger-Dyson. Estudamos a equação de gap fermionica incluindo o efeito de uma massa dinêmica para os gluons. Ao estudar esta equação de gap verificamos que a intenção não é forte o suficiente para gerar uma massa dinâmica dos quarks compatível com os dados experimentais. Também discutimos como a introdução de um propagador confinante pode mudar este cenário, exatamente como foi proposto por Cornwall [1] recentemente, desta forma estudamos uma equação de gap completa, composta pela troca de um gluon massivo e por um termo confinante; M('p POT 2') = 'M IND. c('p POT 2') + 'M IND. 1g'('p POT 2'). Encontramos soluções assintótica desta equação de gap nos casos de constante de acoplamento constante e corredora. Este último caso corresponde a um aprimoramento do cálculo com constante de acoplamento constante feito por Doff, Machado e Natale [2]
Some aspects of chiral symmetry breaking for quarks in the fundamental representation are discussed in the framework of the Schwinger-Dyson equations. We study the fermionic gap equation including effects of dynamical gluon mass. Studying the bifurcation equation of this gap equation we verify that the interaction is not strong enough to generate a satisfactory dynamical quark mass. We also discuss how the introduction of a confining propagator may change this scenario as recently pointed out by Cornwall [1], so we study a complete gap equation composed by the one-dressed-gluon exchange term and a confining term: M('p POT 2') = 'M IND. c('p POT 2') + 'M IND. 1g'('p POT 2'). We find asymptotic solutions for this gap equation in the cases of constant coupling and running coupling constant. This last case is an improvement of the constant coupling calculation of Doff, Machado and Natale [2]
29
Tigg, Jason. "Nonperturbative techniques and the operator product expansion in studies of dynamically broken chiral symmetry." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359504.
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Capdevilla, Roldan Rodolfo Maia. "Dynamical chiral symmetry breaking : the fermionic gap equation with dynamical gluon mass and confinement /." São Paulo, 2013. http://hdl.handle.net/11449/92026.
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Orientador: Adriano Antonio NataleBanca: Adriano Doff Sotta Gomes
Banca: Alex Gomes Dias
Resumo: Alguns aspectos da quebra de simetria quiral para quarks na representação fundamental são discutidos no contexto das equações de Schwinger-Dyson. Estudamos a equação de gap fermionica incluindo o efeito de uma massa dinêmica para os gluons. Ao estudar esta equação de gap verificamos que a intenção não é forte o suficiente para gerar uma massa dinâmica dos quarks compatível com os dados experimentais. Também discutimos como a introdução de um propagador confinante pode mudar este cenário, exatamente como foi proposto por Cornwall [1] recentemente, desta forma estudamos uma equação de gap "completa", composta pela troca de um gluon massivo e por um termo confinante; M('p POT 2') = 'M IND. c('p POT 2') + 'M IND. 1g'('p POT 2'). Encontramos soluções assintótica desta equação de gap nos casos de constante de acoplamento "constante" e "corredora". Este último caso corresponde a um aprimoramento do cálculo com constante de acoplamento "constante" feito por Doff, Machado e Natale [2]
Abstract: Some aspects of chiral symmetry breaking for quarks in the fundamental representation are discussed in the framework of the Schwinger-Dyson equations. We study the fermionic gap equation including effects of dynamical gluon mass. Studying the bifurcation equation of this gap equation we verify that the interaction is not strong enough to generate a satisfactory dynamical quark mass. We also discuss how the introduction of a confining propagator may change this scenario as recently pointed out by Cornwall [1], so we study a "complete" gap equation composed by the one-dressed-gluon exchange term and a confining term: M('p POT 2') = 'M IND. c('p POT 2') + 'M IND. 1g'('p POT 2'). We find asymptotic solutions for this gap equation in the cases of "constant coupling" and "running coupling constant". This last case is an improvement of the constant coupling calculation of Doff, Machado and Natale [2]
Mestre
31
Yunis, Ruhamah. "Synthesis and characterization of amino acid ionic liquids and low symmetry ionic liquids based on the triaminocyclopropenium cation." Thesis, University of Canterbury. Chemistry, 2015. http://hdl.handle.net/10092/10207.
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This thesis involves the synthesis of two main classes of triaminocyclopropenium (tac) Ionic
Liquids (ILs) (i) Amino Acid Ionic Liquids (AAILs) and (ii) reduced-symmetry cations.
[C₃(NEt₂)₂(NRR’)]X (X = TFSA and MeSO₄) were prepared, whereby NHR is derived from amino acids. Optically pure AAILs, [E₄AminoAcid]X (X = TFSA and MeSO₄) were obtained as a mixture of the IL and its zwitterion. The ratios of these mixtures were determined by pH titration and microanalysis. The AAILs specific rotations and pKa values were determined. AAILs can be used for chiral discrimination and form diasterreomeric salts with the entioenriched sodium salt of Mosher’s acid. The AAILs were also successfully used as a solvent and/or catalyst in an aldol reaction and a Diels-Alder reaction.
The low-molecular weight series, [C₃(NMe₂)₂(NRR’)]X and [C₃(NMe₂)₂(NR’2)]X was synthesized and characterized: protic ILs NRR’, where R = ethyl, propyl, allyl, butyl, - CH2CH2OCH₃ and pentyl, R’ = H and X = TFSA: and aprotic ILs NRR’, where R = Me, R’ = ethyl, allyl, propyl, butyl, -CH2CH2OCH₃ and hexyl and X = TFSA and DCA.
ILs with C2v symmetry [C₃(NEt₂)₂(NH2)]X (X = TFSA and MeSO₄), [C₃(NEt₂)₂(NBu2)]I, [C₃(NEt₂)₂(NHex₂)]I and [C₃(NEt₂)₂(NHex₂)]OTf were also synthesized and characterized. The C₃h cations, [C₃(NMeR)₃]X (R = ethyl, allyl, -CH2CH2OCH₃ and phenyl, X = TFSA and DCA) were successfully prepared as well.
The D₃h cation salts [C₃(NEt₂)₃]X (X = MeC6H4SO₃, OTf, I and F5C6O) and [C₃(NBu2)₃]X (X = B(CN)4 and FAP) were also prepared.
The tac-based ILs [C₃(NEt₂)₃]+ and [C₃(NBu2)₃]+ were also complexed with metal halides
- - 2- 2-
forming salts with FeCl₄ , SnCl₃ , CuCl₄
and ZnCl₄ .
Reaction of pentachlorocyclopropane (C₃Cl5H) with BuNH2 gave the open ring allylium product [H2C₃(NBuH)4]2+. This was characterized as Cl- and TFSA- salt. During the synthesis of [C₃(NMe₂)₃]Cl, the open ring cation [HC₃(NMe₂)4]+ was also isolated and was characterized as
the TFSA- salt.
XX
Abstract
The TGA, DSC, density, viscosity, conductivity, and molar conductivity properties for the ILs were measured where possible. The viscosity and conductivity data was fitted for the Arrhenius and Vogel-Fulcher Tamman equations. The entire tac-based ILs lie below the KCl ideal line in Walden plot. A fragility plot was obtained by fitting the viscosity data and all the tac-based ILs were fragile.
The crystal structures of [C₃(NPhH)₃]TFSA, [C₃(NEt₂)₃]FeCl₄ and [HC₃(NMe₂)4]Cl.2CH₃Cl were determined.
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Hackett-Jones, E. J. "The role of chiral symmetry in extrapolations of lattice QCD results to the physical regime /." Title page, contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09SM/09smh121.pdf.
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Cárcamo, Hernández Antonio Enrique. "Composite Vectors and Scalars in Theories of Electroweak Symmetry Breaking." Doctoral thesis, Scuola Normale Superiore, 2011. http://hdl.handle.net/11384/85833.
Full textAbstract:
In the context of a strongly coupled Electroweak Symmetry Breaking, composite triplet of heavy
vectors belonging to the SU(2)L+R adjoint representation and a composite scalar singlet under
SU(2)L+R may arise from a new strong interaction invariant under the global SU(2)L x S(2)R symmetry, which is spontaneously broken down to SU(2)L+R. This thesis consists of two parts.
The first part is devoted to the study of the heavy composite vector pair production at the LHC
via Vector Boson Fusion and Drell-Yan annihilation under the assumption that the interactions
among these heavy vector states and with the Standard Model gauge bosons are described by
a SU(2)L x SU(2)R=SU(2)L+R Effective Chiral Lagrangian. The expected rates of multi-lepton
events from the decay of the composite vectors are also given. The second part studies the
associated production at the LHC of a composite vector with a composite scalar by Vector Boson
Fusion and Drell-Yan annihilation in the framework of a SU(2)L x SU(2)R=SU(2)L+R Effective
Chiral Lagrangian with massive spin one fields and one singlet light scalar. The expected rates of
same sign di-lepton and tri-lepton events from the decay of the composite vector and composite
scalar final state are computed. The connection of the Effective Chiral Lagrangians with suitable
gauge models is elucidated.
34
Smyth, Edward. "Raman optical activity of proteins and glycoproteins." Thesis, University of Glasgow, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312130.
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Rowland, James R. IV. "Theoretical Investigations of Skyrmions in Chiral Magnets." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1565920470204146.
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Böhmer, Christian [Verfasser], and Michael [Akademischer Betreuer] Thies. "Explicit chiral symmetry breaking in Gross-Neveu type models = Explizite chirale Symmetriebrechung in Modelltheorien vom Gross-Neveu Typ / Christian Böhmer. Betreuer: Michael Thies." Erlangen : Universitätsbibliothek der Universität Erlangen-Nürnberg, 2011. http://d-nb.info/1015475000/34.
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Nowakowski, Daniel Verfasser], Michael [Akademischer Betreuer] Buballa, and Jochen [Akademischer Betreuer] [Wambach. "Inhomogeneous chiral symmetry breaking in isospin-asymmetric strong-interaction matter / Daniel Nowakowski ; Michael Buballa, Jochen Wambach." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2017. http://d-nb.info/1131254228/34.
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Nowakowski, Daniel [Verfasser], Michael Akademischer Betreuer] Buballa, and Jochen [Akademischer Betreuer] [Wambach. "Inhomogeneous chiral symmetry breaking in isospin-asymmetric strong-interaction matter / Daniel Nowakowski ; Michael Buballa, Jochen Wambach." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2017. http://nbn-resolving.de/urn:nbn:de:tuda-tuprints-61570.
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Masiteng, Paulus Lukisi. "Gamma spectroscopy and lifetime measurements in the doubly-odd 194tl nucleus, revealing possible chiral symmetry breaking." University of the Western Cape, 2013. http://hdl.handle.net/11394/3991.
Full textAbstract:
Philosophiae Doctor - PhDIn the first experiment high spin states in 194Tl, excited through the 181Ta (18O, 5n) heavyion fusion evaporation reaction were studied using the AFRODITE array at iThemba LABS. The γ-γ coincidences, RAD ratios and linear polarization measurements were carried out and the previously known level scheme of 194Tl was significantly extended. A total of five rotational bands four of which are new were observed. A pair of rotational bands associated with the πh9/2 ⊗ νi−1 13/2 configuration at lower spins and with the πh9/2 ⊗ νi−3 13/2 configuration at higher spins was found and interpreted as the first possible chiral bands followed above the band crossing. The two 4-quasiparticle bands show exceptionally close near-degeneracy in the excitation energies. Furthermore close similarity is also found in their alignments and B(M1)/B(E2) reduced transition probability ratios. In the second experiment lifetimes in 194Tl were measured using the DSAM technique with the excited states in this nucleus populated through the 181Ta (18O, 5n) reaction. A total of 25 lifetimes and 30 reduced transition probabilities of magnetic dipole B(M1) and electric quadrupole B(E2) have been evaluated. Furthermore B(M1) and B(E2) reduced transition probabilities in Bands 1 and 4, which have been regarded as chiral candidates, were found to be close to each other and reveals strong splitting along spin values. This further supports the proposed chiral nature of these two bands.
40
Pupin, Joel César [UNESP]. "Interação nucleon-nucleon devida à troca de três píons e produção de um píon devida à troca de dois píons." Universidade Estadual Paulista (UNESP), 2002. http://hdl.handle.net/11449/102513.
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pupin_jc_dr_ift.pdf: 1428942 bytes, checksum: d6abaa838d7800612f4a795ffa313ad7 (MD5)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Utilizando a simetria quiral, calculamos a contribuição dominante ao potencial nucleon-nucleon (NN) devido à troca de três píons não correlacionados. Esta contribuição é isovetorial com as componentes pseudoescalar e axial. A pseudoescalar é dominante, tem um alcance de 1.0 fm e contribui no canal de píon. No mesmo contexto, estudamos a produção de um píon na interação nucleon-nucleon devida à troca de dois píons. O termo dominante do Kernel da produção é construído a partir da mesma interação básica usada no potencial NN devido à troca de três píons. Relacionamos este termo à componente central do potencial NN devido à troca de dois píons e mostramos que esta, por sua vez, é dominada pelo fator de forma escalar píon-nucleon. O Kernel obtido foi aplicado para o limiar da produção e na construção de um potencial de três nucleons. Os resultados foram generalizados para um potencial NN central qualquer e comparados ao potencial de Argonne e àquele devido à troca de um méson escalar...ctício
Abstracts: Using the chiral symmetry, we calculated the dominant contribution to the nucleon-nucleon (NN) potential due to the exchange of three non-correlated pions (3o). This contribution is isovetor with pseudoscalar and axial components. The pseudoscalar component is dominant, it has a range of 1.0 fm and it contributes in the pion channel. In the same context, we studied the pion production in the nucleon-nucleon interaction due to the exchange of two pions (2o). The dominant term of the production Kernel is built from the same basic interaction used in the 3o-exchange NN potential. We related this term to the central component of the 2o-exchange NN potential and we showed that the latter, on its turn, is dominated by the pion-nucleon scalar form factor. The obtained Kernel was applied at the threshold and in the constructioin of a three-nucleon potential. The results were generalized foa a central NN potential of any kind and compared to the potentials of Argonne and to that due to the exchange of one ...ctitious scalar meson
41
Stranne, Robert. "Investigation of Symmetry and Electronic Effects in Asymmetric Palladium-Catalysed Allylic Substitutions." Doctoral thesis, KTH, Chemistry, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3283.
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Zarnauskas, Gabriel Rocha de Santana. "Os termos sigma do núcleon e da delta." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-06072006-113913/.
Full textAbstract:
O termo sigma do núcleon, $sigma_N$, pode ser extraído dos dados experimentais e permite testar teorias e modelos que buscam descrever os efeitos da quebra explícita de simetria quiral sobre o núcleon. A teoria de perturbação quiral é considerada atualmente a teoria efetiva da cromodinâmica quântica, sendo destinada a descrever o regime de baixas energias das interações fortes. Neste contexto, a expansão do termo sigma do núcleon em função da massa do píon depende das chamadas constantes de baixa energia, que devem ser extraídas da experiência. Neste trabalho apresentamos um modelo em que se elimina este tipo de dependência e fornece valores para $sigma_N$ e o termo sigma da delta, $sigma_Delta$, a partir de parâmetros conhecidos. No caso deste último, este procedimento é particularmente importante, porque não é possível extrair $sigma_Delta$ a partir da experiência, apesar desta grandeza ser fundamental para a obtenção de amplitudes na teoria de perturbação quiral, quando a delta aparece como grau de liberdade explícito. Variando as constantes de acoplamento entre os bárions e o píon, obtivemos resultados nos intervalos 43~MeV~$leq sigma_N leq$~49~MeV e 28~MeV~$leq sigma^R_Delta leq$~32~MeV, compatíveis com resultados de outros grupos. Pela possibilidade da delta decair, o seu termo sigma possui uma parte imaginária, a qual usamos para testar a consistência dos nossos resultados. Analisamos também a contagem de potências e o limite quiral, que mostraram o acordo entre a nossa expansão e a tirada da teoria de perturbação quiral.The nucleon sigma term, $sigma_N$, may be extracted from experimental data and allows theories and models aimed at describing chiral symmetry breaking effects to be tested. At present, chiral perturbation theory is considered the effective theory of quantum chromodynamics at low energies. With this theory, one can obtain an expansion of $sigma_N$ in terms of the pion mass, involving low energy constants, which must be obtained from experiment. In this work we present a model that yields values for both $sigma_N$ and the delta sigma term, $sigma_Delta$, as functions of known parameters only. In the case of $sigma_Delta$, this procedure is particularly relevant, because $sigma_Delta$ is an important quantity in the evaluation of theoretical amplitudes and it is impossible to take it from experimental data. Several choices for pion-baryon coupling constants were used and our results lie in the intervals 43~MeV~$leq sigma_N leq$~49~MeV e 28~MeV~$leq sigma^R_Delta leq$~32~MeV, which are compatible with values produced by other groups. As the delta can decay, its sigma term has an imaginary part that we used to test the consistency of our calculations. The power counting in the chiral limit of our results is consistent with chiral perturbation theory.
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López, Jénifer González. "On the chirally rotated Schrödinger functional with Wilson fermions." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2011. http://dx.doi.org/10.18452/16346.
Full textAbstract:
Viele Phaenomene in der Natur sind eng verknuepft mit dem Niederenergieverhalten der QCD und damit von nicht-perturbative Natur. Viele Groeßen benoetigen auch eine nicht-perturbative Renormierung. Als nicht-perturbative Renormierungsschema schlagen wir das chiral gedrehte Schroedingerfunktional, χSF, in einer Gitterregularisierung vor. Auf dem Baumgraphenniveau wird eine analytische Rechnung im Kontinuum und auf dem Gitter durchgefuehrt. Weitere Untersuchungen werden dann in der Valenzquark-Approximation der Gitter QCD durchgefuehrt. Eines der Hauptziele ist es dabei, die im χSF benoetigten Koeffizienten nicht-perturbativ so einzustellen, dass ein wohl-definierter Kontinuumlimes durchgefuehrt werden kann. Es wird gezeigt, dass solch eine Feineinstellung der Parameter des χSF durchfuehrbar ist und dass physikalische Groeßen nicht sensitiv auf die spezielle Wahl der Bedingung zur Einstellung der Parameter sind. Es wird gezeigt, dass das Skalierungsverhalten physikalischer Groeßen konsistent mit fuehrenden O(a2) Diskretisierungseffekten ist. Das Hauptergebnis dieser Arbeit ist der Nachweis, dass das χSF mit den hier berechneten Verbesserungskoeffizienten, zu einem korrekten Kontinuumlimes fuehrt. Dazu wurden drei unterschiedliche Werte der Renormierungsskala verwendet und mehrere uns interessierende physikalische Groeßen berechnet. Wir koennen deshalb den Schluss ziehen, dass das χSF ein viel versprechendes Renormierungsschema darstellt, um eine nicht-perturbative Renormierung vorzunehmen und dabei gleichzeitig die automatische O(a)-Verbesserung aufrecht erhalten. Dies eroeffnet den sehr wichtigen Ausblick, dass das χSF in zukuenftigen nicht-perturbativen Berechnungen von Renormierungskonstanten auch ueber die Valenzquark-Approximation hinaus eingesetzt werden kann.There are many phenomena in nature which are closely linked to the low energy regime of QCD. Theoretically, these can be dealt with only by means of non-perturbative methods. Often, a non-perturbative renormalization of QCD is required. We employ a 4-dimensional lattice as a regulator of QCD. As a non-perturbative renormalization scheme, we propose the chirally rotated Schrödinger functional, χSF. We perform analytical studies at tree-level of perturbation theory, in the continuum and on the lattice. Beyond tree-level, all studies are performed in the quenched approximation of QCD. One of the main targets has been to perform the non-perturbative tuning of the two required coefficients of the χSF scheme, such that a well defined continuum limit can be reached. We demonstrate that the tuning is feasible and physical quantities are insensitive to the tuning condition. There are also a couple of improvement counterterms at the boundaries. However, besides these boundary O(a) effects, the χSF is expected to be compatible with bulk automatic O(a)-improvement. We show that the scaling behavior of physical quantities is consistent with automatic O(a)-improvement. The other most important achievement has been to demonstrate that the χSF, with the here computed tuning coefficients, leads to the correct continuum limit. For this, we have performed universality tests of the continuum limit, at three different values of the renormalization scale and through the computation of several physical quantities of interest. The conclusion of these results is that the χSF is a promising scheme to perform non-perturbative renormalizations while maintaining bulk automatic O(a)-improvement. This opens the most relevant prospect that the χSF can be safely used in future non-perturbative computations of renormalization factors also beyond the quenched approximation.
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Messina, Emanuele. "Non perturbative renormalization of firmion theories." Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/936.
Full textAbstract:
The present work is devoted to the study of the non-perturbative renormalization of quantum
field theories (QFT) of self-interacting fermions,
which is investigated with the help of a fermion Wilsonian RG method.
By starting with the appropriate scale dependent action S_k for fermion models and performing a non-trivial extension of previous techniques, a new renormalization group (RG) equation for a generalized N flavors Gross-Neveu model in 2 ¿ d ¿ 4 dimensions is established.
The renormalizability of such a model is related to the
existence of a non-Gaussian fixed point of the RG equations, which
turns out also to be related to the critical point of the
chiral symmetry breaking.
Within the Wilson RG approach to critical phenomena, the
critical exponents of the Gross-Neveu model are computed by considering the behaviour of the running mass m(k) and Fermi constant G(k)
around such a non-Gaussian fixed point (with divergent correlation length).
By means our approach, this model can be
studied even far from the applicability domain of other traditional analytical tools (as epsilon or 1/N expansion) relying on the bosonization
of the model.
The RG equations for the running mass m(k) and Fermi constant G(k)
are numerically studied in
the whole (G, m) plane. From this analysis, in turns out that the physics of the chiral
phase transition can be described well in terms of a cross-over phenomenon triggered by
the presence of an infinitesimal bare mass.
The impact of higher powers operators (¿¿)^4 in the Wilsonian potential is also considered.
In the large N limit,
the failure of the hyperscaling and the presence of
a logarithmic behaviour at d=4 dimensions with the scale of the quartic operator (¿¿)^4 are thus recovered in our RG fermion language.
By considering the impact of odd interaction terms in the potential, the marginality
of the cubic operator in d = 3 dimensions is also recovered. The anomalous dimension of this
operator is computed and found to be in agreement with results given in the literature at
the next to leading order in the 1/N expansion.
Finally the Wilsonian RG equation is extended to theories which involve both fermions
and bosons. For N=1 and d=4 this equation coincides with that found in
literature. A non-trivial FP which should describe the chiral transition for
d<4 is then found.
If, however, a four Fermi interaction term is added to the Yukawa theory,
an intriguing and unexpected result is found. Namely, the non-perturbative
scaling of the running Fermi constant G(k) triggers the appearence of a
non-Gaussian fixed point which heals the triviality of the Yukawa coupling
in d=4 dimensions.
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Thomas, Ronny. "In-Medium QCD Sum Rules for omega Meson, Nucleon and D Meson." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1233231634620-61511.
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The modifications of hadronic properties caused by an ambient nuclear medium are investigated within the scope of QCD sum rules. This is exemplified for the cases of the omega meson, the nucleon and the D meson. By virtue of the sum rules, integrated spectral densities of these hadrons are linked to properties of the QCD ground state, quantified in condensates. For the cases of the omega meson and the nucleon it is discussed how the sum rules allow a restriction of the parameter range of poorly known four-quark condensates by a comparison of experimental and theoretical knowledge. The catalog of independent four-quark condensates is covered and relations among these condensates are revealed. The behavior of four-quark condensates under the chiral symmetry group and the relation to order parameters of spontaneous chiral symmetry breaking are outlined. In this respect, also the QCD condensates appearing in differences of sum rules of chiral partners are investigated. Finally, the effects of an ambient nuclear medium on the D meson are discussed and relevant condensates are identifiedDie Veränderungen von Hadroneneigenschaften durch ein umgebendes nukleares Medium (Kernmaterie) werden mit der Methode der QCD-Summenregeln untersucht. Dies wird am Beispiel des omega-Mesons, des Nukleons und des D-Mesons vorgeführt. Durch die Summenregeln werden integrierte Spektraldichten dieser Hadronen in Beziehung zu Eigenschaften des QCD-Grundzustandes, quantifiziert in Kondensaten, gesetzt. Diskutiert wird am Beispiel des omega-Mesons und des Nukleons, wie diese Summenregeln eine Einschränkung des Parameterbereiches von wenig bekannten Vierquark-Kondensaten durch Vergleich von experimentellen und theoretischen Erkenntnissen erlauben. Ein Katalog unabhängiger Vierquark-Kondensate wird aufgestellt und Relationen zwischen diesen Kondensaten werden deutlich gemacht. Das Verhalten der Vierquark-Kondensate unter der chiralen Symmetriegruppe und der Zusammenhang mit Ordnungsparametern spontaner chiraler Symmetriebrechung werden behandelt. In dieser Hinsicht werden auch die in Differenzen der Summenregeln chiraler Partner eingehenden QCD-Kondensate untersucht. Schließlich werden die Effekte endlicher Kerndichten beim D-Meson diskutiert und relevante Kondensate identifiziert
46
Timóteo, Varese Salvador. "Álgebras Deformadas no Modelo NJL: Quebra e Restauração da Simetria Quiral." Universidade de São Paulo, 2000. http://www.teses.usp.br/teses/disponiveis/43/43131/tde-24102012-174119/.
Full textAbstract:
Este trabalho é resultado de uma série de estudos feitos com o objetivo de investigar a influ- ência de uma álgebra fermiônica deformada nos mecanismos de quebra e restauração da si- metria quiral no modelo de Nambu-Jona-Lasinio. Esse modelo foi escolhido pois é um modelo efetivo para a QCD que mostra com razoável facilidade uma de suas principais características, a quebra dinâmica da simetria quiral e a geração de uma massa dinâmica para os quarks. O trabalho pode ser dividido essencialmente em três partes. A primeira consiste em um estudo inicial onde a deformação foi implementada diretamente na equação de gap do modelo NJL através de um cálculo deformado do condensado. Na segunda parte, o mesmo procedimento de deformação foi aplicado na Hamiltoniana do modelo permitindo que seus efeitos se propagem nos cálculos até uma nova equação de gap. Uma extensão natural do trabalho e um estudo do modelo deformado a temperatura finita, onde a coexistência da temperatura e da deformação algébrica pode ser investigada. Esse estudo e a terceira parte do trabalhoThis work is a result of a serie of studies where the aim is to investigate the influence of a de- formed fermionic algebra in the mechanisms of breaking and restoration of chiral symmetry in the Nambu-Jona-Lasinio model. This model was chosen because it is an effective model for QCD which shows with reasonable facility one of its main features, the dynamical breaking of chiral symmetry and the generation of a dynamical mass for the quarks. The work can be divided essentialy in three parts. The first consists in a initial study where the deformation was implemented directly in the gap equation of the NJL model through a defor- med calculation of the condensates. In second part, the same deformation procedure was applied in the Hamiltonian of the model allowing their effects to be propagated in the calcula- tions till a new gap equation. A natural extension of the work is a study of the deformed model at finite temperature, where the coexistence of temperature and algebric deformation can be investigated. This study is the third part of the work.
47
Pupin, Joel César. "Interação nucleon-nucleon devida à troca de três píons e produção de um píon devida à troca de dois píons /." São Paulo : [s.n.], 2002. http://hdl.handle.net/11449/102513.
Full textAbstract:
Orientador: Manoel Roberto RobilottaBanca: José de Sá Borges Filho
Banca: Manuel M. B. Malheiro de Oliveira
Banca: Lauro Tomio
Banca: Alfredo Pio Noronha Rodrigues Galeão
Resumo: Utilizando a simetria quiral, calculamos a contribuição dominante ao potencial nucleon-nucleon (NN) devido à troca de três píons não correlacionados. Esta contribuição é isovetorial com as componentes pseudoescalar e axial. A pseudoescalar é dominante, tem um alcance de 1.0 fm e contribui no canal de píon. No mesmo contexto, estudamos a produção de um píon na interação nucleon-nucleon devida à troca de dois píons. O termo dominante do Kernel da produção é construído a partir da mesma interação básica usada no potencial NN devido à troca de três píons. Relacionamos este termo à componente central do potencial NN devido à troca de dois píons e mostramos que esta, por sua vez, é dominada pelo fator de forma escalar píon-nucleon. O Kernel obtido foi aplicado para o limiar da produção e na construção de um potencial de três nucleons. Os resultados foram generalizados para um potencial NN central qualquer e comparados ao potencial de Argonne e àquele devido à troca de um méson escalar ...ctício
Abstracts: Using the chiral symmetry, we calculated the dominant contribution to the nucleon-nucleon (NN) potential due to the exchange of three non-correlated pions (3o). This contribution is isovetor with pseudoscalar and axial components. The pseudoscalar component is dominant, it has a range of 1.0 fm and it contributes in the pion channel. In the same context, we studied the pion production in the nucleon-nucleon interaction due to the exchange of two pions (2o). The dominant term of the production Kernel is built from the same basic interaction used in the 3o-exchange NN potential. We related this term to the central component of the 2o-exchange NN potential and we showed that the latter, on its turn, is dominated by the pion-nucleon scalar form factor. The obtained Kernel was applied at the threshold and in the constructioin of a three-nucleon potential. The results were generalized foa a central NN potential of any kind and compared to the potentials of Argonne and to that due to the exchange of one ...ctitious scalar meson
Doutor
48
Schmidt, Daniel [Verfasser], Andreas [Gutachter] Wipf, Urs [Gutachter] Wenger, and Simon [Gutachter] Hands. "Three-dimensional four-fermion theories with exact chiral symmetry on the lattice / Daniel Schmidt ; Gutachter: Andreas Wipf, Urs Wenger, Simon Hands." Jena : Friedrich-Schiller-Universität Jena, 2018. http://d-nb.info/117039826X/34.
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Uwaha, Makio. "Simple Models for Chirality Conversion of Crystals and Molecules by Grinding." The Physical Society of Japan, 2008. http://hdl.handle.net/2237/13865.
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Cavalcante, Isabela Porto. "A Interação Nucleon-Nucleon no Modelo de Skyrme." Universidade de São Paulo, 1999. http://www.teses.usp.br/teses/disponiveis/43/43131/tde-27022014-143037/.
Full textAbstract:
A interação forte a baixas energias pode ser abordada por meio de lagrangianas efetivas. Nesse contexto, o modelo de Skyrme representa uma forma de descrever bárions, que emergem como sólitons topológicos de uma lagrangiana mesônica quiral. A interação nucleon-nucleon (NN) é comumente tratada neste modelo de maneira aproximada, através do chamado Ansatz Produto (AP), cujo problema mais sério é não reproduzir a atração de alcance intermediário no canal escalar-isoescalar do potencial NN. O objetivo deste trabalho é construir um novo ansatz para o cálculo da interação NN no modelo de Skyrme. Para isso, analisamos o AP, investigando as causas deste problema fenomenológico, e concluímos que deve-se à componente azimutal de seu campo piônico. A partir disto, construímos o Ansatz Novo (AN), com o qual calculamos o novo potencial. Comparando os resultados com outros potenciais existentes, mostramos que o AN constitui uma solução plausível para o problema.Strong interactions at low energies can be treated by means of effective lagrangians. In this context, the Skyrme model is regarded as a way to describe baryons as topological solitons from a chiral mesonic lagrangian. In the framework of this model, nucleon-nucleon (NN) interaction is usually derived in the sudden approximation, by means of the so called Product Ansatz (PA). Its most serious problem is the absence of the intermediate range attraction in the scalar-isoscalar channel of the NN potential. We construct a new ansatz to derive the NN interaction in the Skyrme model. At first, we analise the PA and investigate the causes of its phenomenological problem. We conclude it is due to the azimuthal component of its pionic field. With this result we build the New Ansatz (NA) and calculate the new potential. Comparisons of the results with other existent potentials show that NA constitutes a plausible solution to the problem.