Дисертації з теми "Effective field theory; QCD; lattice QCD"
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Husung, Nikolai. "Logarithmic corrections in Symanzik’s effective theory of lattice QCD." Doctoral thesis, Humboldt-Universität zu Berlin, 2021. http://dx.doi.org/10.18452/22944.
Повний текст джерелаOne of the final steps in simulations of lattice Quantum Chromodynamics (QCD) or lattice pure gauge theory is the continuum extrapolation to extract the actual continuum physics. This extrapolation relies heavily on assumptions regarding the asymptotic dependence on the lattice spacing, which introduces an inherent systematic uncertainty to the continuum limit. In classical field theories the asymptotic form is a power series in the lattice spacing, where the leading power depends on the chosen lattice discretisation. The quantum nature of lattice QCD and lattice pure gauge theory spoils this behaviour. For asymptotically free theories like lattice QCD the integer powers in the lattice spacing are multiplied by an additional power in the running coupling. The leading powers in the coupling can be determined from the anomalous dimensions of higher dimensional operators, which form a minimal basis of a Symanzik Effective theory. The scope of this thesis is to compute the leading powers in the coupling for the Wilson or Ginsparg-Wilson (GW) action relevant for spectral quantities like hadron masses. The lower bound of these powers is close to zero for lattice QCD with Wilson or GW quarks such that no problems from a reduced convergence towards the continuum limit are to be expected. However the spectrum of leading powers is very dense. The operator of the minimal basis with dominant contributions to the lattice artifacts is thus hard to determine and complicated interplay of the contributions from the various operators is possible. Now the leading corrections from lattice actions with Wilson or GW quarks to the classical power in the lattice spacing are known and should be used when performing the continuum extrapolation both through explicit use in the fit ansatz and as an orientation to estimate the systematic uncertainty inherent to the continuum limit.
Bär, Oliver. "Chiral perturbation theory for lattice QCD." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2011. http://dx.doi.org/10.18452/13976.
Повний текст джерелаThe formulation of chiral perturbation theory (ChPT) for lattice Quantum Chromodynamics (QCD) is reviewed. We start with brief summaries of ChPT for continuum QCD as well as the Symanzik effective theory for lattice QCD. We then review the formulation of ChPT for lattice QCD. After an additional chapter on partial quenching and mixed action theories various concrete applications are discussed: Wilson ChPT, staggered ChPT and Wilson ChPT with a twisted mass term. The remaining chapters deal with the epsilon regime with Wilson fermions and selected results in mixed action ChPT. Finally, the formulation of heavy vector meson ChPT with Wilson fermions is discussed.
Ren, Xiulei. "Effective Field Theory for Baryon Masses." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS156/document.
Повний текст джерелаMass is one of the most fundamental properties of matter. Understanding its origin has long been a central topic in physics. According to modern particle and nuclear physics, the key to this issue is to understand the origin of nucleon (lowest-lying baryon) masses from the nonperturbative strong interaction. With the development of computing technologies, lattice Quantum Chromodynamics simulations provide great opportunities to understand the origin of mass from first principles. However, due to the limit of computational resources, lattice baryon masses have to be extrapolated to the physical point. Chiral perturbation theory, as an effective field theory of low-energy QCD, provides a model independent method to understand nonperturbative strong interactions and to guide the lattice multiple extrapolations. Therefore, we present the interplay between lattice QCD and chiral perturbation theory to systematically study the baryon masses. In the SU(3) sector, we study the lowest-lying octet baryon masses in covariant baryon chiral perturbation theory with the extended-on-mass-shell scheme up to next-to-next-to-next-to-leading order. In order to consider lattice artifacts from finite lattice box sizes, finite-volume corrections to lattice baryon masses are estimated. By constructing chiral perturbation theory for Wilson fermions, we also obtain the discretization effects of finite lattice spacings. We perform a systematic study of all the latest n_f=2+1 lattice data with chiral extrapolation (m_q → m_q^phys.), finite-volume corrections (V→∞), and continuum extrapolation (a→0). We find that finite-volume corrections are important to describe the present lattice baryon masses. On the other hand, the discretization effects of lattice simulations up to O(a²) are of the order 1% when a≈0.1 fm and can be safely ignored. Furthermore, we find that the lattice data from different collaborations are consistent with each other, though their setups are quite different. Using the chiral formulas of octet baryon masses, we accurately predict the octet baryon sigma terms via the Feynman-Hellmann theorem by analyzing the latest high-statistics lattice QCD data. Three key factors --- lattice scale setting effects, chiral expansion truncations and strong-interaction isospin-breaking effects --- are taken into account for the first time. In particular, the predicted pion- and strangeness-nucleon sigma terms, sigma_πN=55(1)(4) MeV and sigma_sN =27(27)(4) MeV, are consistent with the most latest lattice results of nucleon sigma terms. With the success in the study of octet baryon masses, we also present a systematic analysis of the lowest-lying decuplet baryon masses in covariant baryon chiral perturbation theory by simultaneously fitting n_f=2+1 lattice data. A good description for both the lattice and the experimental decuplet baryon masses is achieved. The convergence of covariant baryon chiral perturbation theory in the SU(3) sector is discussed. Furthermore, the pion- and strangeness-sigma terms for decuplet baryons are predicted by the Feynman-Hellmann theorem. In addition, understanding the excitation spectrum of hadrons is still a challenge, especially the first positive-parity nucleon resonance, the Roper(1440). The baryon spectrum shows a very unusual pattern that the Roper state is lower than the negative-parity state N(1535). Most lattice studies suggest that the Roper mass exhibits much larger chiral-log effects than that of the nucleon. Therefore, we calculate the Roper mass in chiral perturbation theory by explicitly including the nucleon/Delta contributions. The mixed contributions between nucleon and Roper to the baryon masses are taken into account for the first time. A first analysis of lattice Roper masses is presented
Toucas, Guillaume. "Mécanisme de brisure de symétrie chirale pour trois saveurs de quarks légers et extrapolation de résultats de chromodynamique quantique sur réseau." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00754994.
Повний текст джерелаMcCallum, Paul. "Upsilon spectroscopy using lattice QCD." Thesis, University of Glasgow, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363170.
Повний текст джерелаGough, Bran James. "Calculation of rare B decays in lattice QCD." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241262.
Повний текст джерелаFickinger, Michael, Sean Fleming, Chul Kim, and Emanuele Mereghetti. "Effective Field Theory approach to heavy quark fragmentation." SPRINGER, 2016. http://hdl.handle.net/10150/623954.
Повний текст джерелаVan, de Water Ruth S. "Applications of chiral perturbation theory to lattice QCD /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/9730.
Повний текст джерелаIdilbi, Ahmad S. "QCD resummation of soft gluons in effective field theory." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3317.
Повний текст джерелаThesis research directed by: Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
Husung, Nikolai [Verfasser]. "Logarithmic corrections in Symanzik’s effective theory of lattice QCD / Nikolai Husung." Berlin : Humboldt-Universität zu Berlin, 2021. http://d-nb.info/1238595316/34.
Повний текст джерелаLesk, Victor Isaac. "Heavy-light hadron matrix elements from lattice QCD." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323943.
Повний текст джерелаHarrison, Judd Gavin Ivo Henry. "Lattice QCD determination of weak decays of B mesons." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/286066.
Повний текст джерелаCrompton, P. R. "Lee-Yang zeros analysis of finite density lattice QCD." Thesis, University of Glasgow, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368583.
Повний текст джерелаWu, Jackson M. S. "Improvement of Wilson fermions and twisted mass lattice QCD /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/9706.
Повний текст джерелаFoster, Martyn Stuart. "Adjoint sources, disconnected loops and other fruit of lattice QCD." Thesis, University of Liverpool, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366408.
Повний текст джерелаSharkey, Kieran James. "An investigation of the running coupling and meson masses in lattice QCD." Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343926.
Повний текст джерелаVolmer, Julia Louisa. "New attempts for error reduction in lattice field theory calculations." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19350.
Повний текст джерелаLattice QCD is a very successful tool to compute QCD observables non-perturbatively from first principles. The therefore needed evaluation of the QCD path integral consists of two parts: first, sampling points are generated at which second, the path integral is evaluated. The first part is typically achieved by Markov-chain Monte Carlo (MCMC) methods which work very well for most applications but also have some issues as their slow error scaling and the numerical sign-problem. The second part includes the computation of quark connected and disconnected diagrams. Improvements of the signal-to-noise ratio have to be found since the disconnected diagrams, though their estimation being very noisy, contribute significantly to physical observables. Methods are proposed to overcome the aforementioned difficulties in both parts of the evaluation of the lattice QCD path integral and therefore to estimate observables more efficiently and more accurately. For the computation of quark disconnected diagrams we tested the exact eigenmode reconstruction with deflation method and found that this method resulted in a 5.5-fold reduction of runtime. To address the difficulties of MCMC methods, we tested the recursive numerical integration method, which simplifies the evaluation of the integral. We applied the method in combination with a Gauss quadrature rule to the one-dimensional quantum-mechanical rotor and found that we can compute error estimates that scale exponentially to the correct result. A generalization to higher space-time dimensions can be done in the future. Additionally, we developed the symmetrized quadrature rules to address the sign-problem. We applied them to the one-dimensional QCD with a chemical potential and found that this method is capable of overcoming the sign-problem completely and is very efficient for models with one variable. Improvements of the efficiency for multi-variable scenarios can be made in the future.
Sajjad, Aqil. "An effective theory on the light shell." Thesis, Harvard University, 2014. http://nrs.harvard.edu/urn-3:HUL.InstRepos:13064982.
Повний текст джерелаPhysics
Mori, Yuto. "Path optimization with neural network for sign problem in quantum field theories." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263466.
Повний текст джерелаKhamseh, Ava. "Lattice phenomenology of heavy quarks using dynamical fermions." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28855.
Повний текст джерелаMétivet, Thibaut. "Lattice QCD at the physical point : pion-pion scattering and structure of the nucleon." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112243/document.
Повний текст джерелаThe formalism of Quantum Chromodynamics on the lattice (or Lattice QCD) allows to perform ab-initio non-perturbative studies of strong-interaction driven processes, as it provides both a covariant regularisation of the theory of QCD and a natural framework for numerical computations. In this work, after a review of the main features of QCD and a step-by-step presentation of our discretization of QCD on a lattice, we undertake detailed studies of two problems of hadronic physics: the phenomenon of resonant scattering and the structure of the nucleon. The lattice calculations are performed with the Budapest-Marseille-Wuppertal Collaboration's 2+1-flavour gauge configurations, which give access to a wide range of lattice spacings, volumes and quarks masses, thereby allowing to study the sensibility of our results on these parameters, and to perform a complete continuum extrapolation. These configurations include dynamical quarks, and use a clover-improved Wilson QCD action. To investigate the scattering of particles on the lattice, we set up a Lüscher analysis for the emblematic case of pion-pion scattering in the channel of the rho meson resonance. We analyse our data with a variational generalized eigenvalue method, and give an in-depth calculation of the scattering phase-shifts and the corresponding resonance parameters, with a full control of the systematic errors. Our results provide an important step for lattice studies of scattering states, as they are the first to be performed at the physical pion mass, where one can see the actual decay of the rho into two pions. The obtained rho meson parameters are in good agreement with the experimental values, and consistent with a weak pion mass dependence of the coupling between the rho and two pions. As for our probe of the structure of the nucleon, we present a complete extraction of the electroweak isovector form factors, with a comprehensive study of the electric charge squared radius and of the axial charge. Our analysis also feature data at the physical pion mass, which turns out to be crucial in order to perform safe extrapolations to the physical point, as the chiral perturbation theory predicts violent variations of these quantities near the massless-quarks point. Our calculation includes source and sink projections onto the nucleon state, as well as a combined fit method between the two-point and three-point correlation functions to control the contamination of our data by excited states. Although one would need more data to perform a high-accuracy determination of the nucleon radius and axial charge at the physical point with a relevant estimation of the systematic errors, the results we obtain are in good agreement with the experiment and suggest that the excited-state effects are under control. Our analysis also highlights that gauge configurations ensembles near the physical pion mass and with large volumes must be used in order to extract accurate information about the nucleon structure from lattice calculations
Thapaliya, Arbin. "Topics In Effective Field Theories for the Strong Interaction." Ohio University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1469562777.
Повний текст джерелаMalak, Rehan. "Contribution à l'ordre dominant de la polarisation hadronique du vide au moment magnétique anomal du muon en QCD sur réseau avec quatre saveurs de quarks à leur masse physique." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4089.
Повний текст джерелаThe anomalous magnetic moments of leptons have played an important role in the development of the Standard Model of particle physics. Today, that of the muon is measured very precisely and will be so with even higher precision in an experiment that will begin in 2017. To the extent that the theoretical prediction can be made with comparable uncertainties, a rigorous test of the Standard Model will be possible. Here we study the limiting factor in this prediction, the leading-order hadronic vacuum polarization contribution (HVP-LO). We compute this contribution numerically with a discretized version of the theory of the strong interaction: lattice Quantum Chromodynamics. High-performance computing allows to solve the theory in its highly nonlinear regime, which is the one most relevant here. The simulation algorithms and the methods used to obtain the HVP, as well as the associated statistical and systematic uncertainties, are described. These methods are then applied to simulations performed with the Budapest-Marseille-Wuppertal collaboration. First they are implemented in a dedicated study of finite-volume effects. The most robust methods are then used to compute the HVP with simulations which include N_f=2+1+1 flavors of quarks. These are performed directly at the physical values of the u, d, s and c quark masses, with six lattice spacings and in large volumes of 6 fm^3. They allow us to compute the HVP-LO contribution to the anomalous magnetic moment of the muon with controlled errors of around 3%
Söderberg, Alexander. "Renormalization in Field Theories." Thesis, Uppsala universitet, Teoretisk fysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-251561.
Повний текст джерелаSalehi, Kasmaei Babak. "NONEQUILIBRIUM PROBES OF THE QUARK-GLUON PLASMA." Kent State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=kent1627035862984205.
Повний текст джерелаHall, Jonathan Michael MacGillivray. "Chiral effective field theory beyond the power-counting regime." Thesis, 2011. http://hdl.handle.net/2440/70890.
Повний текст джерелаThesis (Ph.D.) -- University of Adelaide, School of Chemistry and Physics,, 2011
"Effective Field Theory for Doubly Heavy Baryons and Lattice QCD." Diss., 2009. http://hdl.handle.net/10161/1056.
Повний текст джерелаHu, Jie. "Effective field theory for doubly heavy baryons and lattice QCD." Diss., 2009. http://hdl.handle.net/10161/380.
Повний текст джерелаBoinepalli, Sharada. "Electromagnetic properties of baryons from lattice QCD." 2006. http://hdl.handle.net/2440/38005.
Повний текст джерелаThesis (Ph.D.)--School of Chemistry and Physics, 2006.
Boinepalli, Sharada. "Electromagnetic properties of baryons from lattice QCD." Thesis, 2006. http://hdl.handle.net/2440/38005.
Повний текст джерелаThesis (Ph.D.)--School of Chemistry and Physics, 2006.
Xu, Yiming. "Low-energy effective descriptions of Dark Matter detection and QCD spectroscopy." Thesis, 2014. https://hdl.handle.net/2144/15287.
Повний текст джерелаPrimer, Thomas James. "Magnetic properties of the nucleon in a uniform background field." Thesis, 2013. http://hdl.handle.net/2440/83782.
Повний текст джерелаThesis (Ph.D.) -- University of Adelaide, School of Chemistry and Physics, 2013
Powell, Joshua. "Exotic States in Quarkonium Physics: Effective Theories of Heavy Mesonic Molecules and an AdS/QCD Model of Hybrid Quarkonium." Diss., 2013. http://hdl.handle.net/10161/8214.
Повний текст джерелаQuantum chromodynamics (QCD), the theory of quarks and gluons, is known to be
the correct description of strong nuclear interactions. At high energy and momenta,
one can use QCD directly to compute quantities of physical interest related to the
strong force. At low energies and momenta, one should use a different description in
terms of the degrees of freedom relevant at that scale. Two approaches to achieve
this end are effective field theories and gauge/gravity dualities. The former involves
a field theory more or less like QCD itself, but with states which are composites
of quarks and gluons. Then a perturbative expansion is made not in terms of the
gauge coupling but instead in terms of the momentum of the fields. This approach
dates back to the 1970s and is on firm theoretical footing. Gauge/gravity dualities
are a newer and less understood technique, which relates the physics of the strong
interactions to a different but likely equivalent theory in a higher dimensional space-
time, where the quantity of interest can be computed more readily. We employ
both effective field theories and gauge/gravity dualities to study the physics of ex-
otic quarkonium states, that is bound states containing a heavy quark-antiquark pair
which nevertheless cannot be be understood working only with the standard quark
model of hadrons. Candidates for such states, long speculated to exist, have recently
been observed at particle colliders, so that the theory of exotic quarkonium is now
of great experimental importance.
Dissertation