Kaon decays and other hadronic processes in lattice qcd
- Autores: Fernando Romero López
- Directores de la Tesis: Pilar Hernández Gamazo (dir. tes.), Stephen Roger Sharpe (codir. tes.)
- Lectura: En la Universitat de València ( España ) en 2021
- Idioma: español
- Tribunal Calificador de la Tesis: Akaki Rusetski (presid.), Margarita Garcia Perez (secret.), Hartmut Wittig (voc.)
- Programa de doctorado: Programa de Doctorado en Física por la Universitat de València (Estudi General)
- Materias:
- Enlaces
- Tesis en acceso abierto en: webges.uv.es (pdf)
- Resumen
This doctoral thesis deals with the study of properties and interactions of light mesons. More specifically, we focus on hadronic decay and scattering processes, which are dominated by effects of the strong interaction in the low-energy regime. Concrete examples that will be addressed are the weak decay of a kaon into two pions, and the scattering of three pions.
A peculiarity of the strong interaction is that perturbative expansions fail at hadronic energy scales. For this reason, genuine nonperturbative tools are essential to obtain first-principles predictions. The central technique employed in this work is Lattice Field Theory, which uses a discretized spacetime to stochastically estimate physical quantities in a quantum field theory. We will also make use of Effective Field Theories, as they provide a complementary description to the dynamics of light hadrons. The mathematical formulation of the strong interaction—Quantum Chromodynamics (QCD)—and the methods to resolve its dynamics will be addressed in Chapter 1.
The original research of this dissertation is divided in two parts, each with a dedicated chapter. Chapter 2 describes our study of the ’t Hooft limit of QCD using lattice simulations, while in Chapter 3 we consider processes that involve multiparticle states.
The ’t Hooft limit provides a simplification of nonabelian gauge theories that leads to precise nonperturbative predictions. We will analyze the scaling with the number of colours of various observables, such as meson masses, decay constants and weak transition matrix elements. An important question we address is the origin of the long-standing puzzle of the Delta I = 1/2 rule, that is, the large hierarchy in the isospin amplitudes of the K to pipi weak decay. This is an example in which the ’t Hooft limit seems to fail.
Regarding multiparticle processes, we will discuss generalizations of the well-established L¨uscher formalism to explore three-particle processes from lattice simulations. The focus will be on the highlights of our contribution, such as our implementation of the finite-volume formalism that includes higher partial waves, and the first application of the formalism to a full lattice QCD spectrum. We will also comment on the extension of the approach to generic three-pion systems. These will enable lattice explorations of scattering processes in some resonant channels, as well as phenomenologically interesting decays to three pions.
A detailed summary in Spanish of the motivations, methodology, results and achievements of this thesis will be given in Chapter 4. The final part of the thesis (Part II) includes the peer-reviewed publications that constitute the body of this dissertation. Their original published form has been kept.
