Sökning: "effective field theory"

Visar resultat 21 - 25 av 196 avhandlingar innehållade orden effective field theory.

  1. 21. Efficient sampling of Bayesian posteriors and predictive distributions in χEFT

    Författare :Isak Svensson; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; chiral effective field theory; Bayesian parameter estimation; nuclear physics; Markov chain Monte Carlo; two-nucleon scattering;

    Sammanfattning : In this thesis I employ Bayesian statistics to quantify parametric and epistemic uncertainties in chiral effective field theories (χEFT) and propagate these forward to predictions of observables in low-energy nuclear physics. Two primary sources of uncertainty---experimental errors and the theoretical error induced by the truncation of the EFT at up to next-to-next-to-leading-order---are modelled and accounted for in the posterior distributions of the unknown low-energy constants (LECs) that govern interaction strengths in χEFT. LÄS MER

  2. 22. Multi-Meson Dynamics in Chiral Perturbation Theory

    Författare :Mattias Sjö; Partikel- och kärnfysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Spridningsamplituder; Effektiv Fältteori; Spontant symmetribrott; Ickelinjära sigmamodellen; Kirala Lagrangianer; Hadronspektroskopi; Strukturer och Interaktioner; Gitter-QCD; Scattering amplitudes; Effective Field Theories; Spontaneous Symmetry Breaking; Nonlinear sigma model; Chiral Lagrangians; Hadronic Spectroscopy; Structure and Interactions; Lattice QCD;

    Sammanfattning : This thesis concerns scattering of light mesons in the case where the number of external particles exceeds four (that is, three or more particles in the initial or final state), calculated using chiral perturbation theory.This is both of theoretical interest in the study of scattering amplitudes, and relevant for systems of three or more pions simulated using lattice quantum chromodynamics. LÄS MER

  3. 23. Fermions in two dimensions and exactly solvable models

    Författare :Jonas de Woul; Edwin Langmann; Fabian Essler; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Bosonization; Exactly solvable models; Hubbard model; Mean field theory; Quantum field theory; Strongly correlated systems;

    Sammanfattning : This Ph.D. thesis in mathematical physics concerns systems of interacting fermions with strong correlations. For these systems the physical properties can only be described in terms of the collective behavior of the fermions. LÄS MER

  4. 24. Studies of effective theories beyond the Standard Model

    Författare :Stella Riad; Tommy Ohlsson; Mattias Blennow; Johan Rathsman; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Effective field theories; neutrino physics; extra dimensions; universal extra dimensions; Higgs physics; renormalization group running; Bayesian statistics; coupling scale factor; grand unified theories;

    Sammanfattning : The vast majority of all experimental results in particle physics can be described by the Standard Model (SM) of particle physics. However, neither the existence of neutrino masses nor the mixing in the leptonic sector, which have been observed, can be described within this model. LÄS MER

  5. 25. Correlated Electronic Structure of Materials : Development and Application of Dynamical Mean Field Theory

    Författare :Patrik Thunström; Olle Eriksson; Alexander Lichtenstein; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; DFT; DMFT; correlation; entanglement; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Sammanfattning : This thesis is dedicated to the development, implementation and application of a combination of Density Functional Theory and Dynamical Mean Field Theory. The resulting program is shown through several examples to be a powerful and flexible tool for calculating the electronic structure of strongly correlated materials. LÄS MER