Higher-order behaviour of heavy-quark current correlators in the small-momentum expansion

• Ano de defesa: 2021
• Autor(a) principal: Rodrigues, Marcus Vinícius Gonzalez
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Acoplamento forte; Massas dos quarks; Perturbative QCD; QCD perturbativa; Quark masses; Renormalons; Strong coupling
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/76/76134/tde-13122021-115817/

In the absence of direct observations of new physics at the LHC, precision physics plays an important role in the search for phenomena beyond the Standard Model (SM). In this situation, the fundamental parameters of the SM, such as quark masses and the strong coupling, αs, must be known with high precision. One of the most powerful methods to extract the charm- and bottom-quark masses, mc and mb, as well as the strong coupling, is the use of sum-rules for the vector and pseudo-scalar heavy-quark current correlators. At present, the increasing precision of experimental data and lattice simulations may not directly translate into more accurate determinations of mc, mb and αs, as the perturbative uncertainty due to the residual renormalization-scale dependence dominates the final error of these parameters. In this work, we extended the analysis of Grozin and Sturm for the vector correlator and calculated, for the first time, the small-momentum expansion of the pseudo-scalar, scalar and axial-vector correlators in the large-β0 limit. We performed a detailed study of the singularities of the Borel transforms and the higher-order behaviour of the perturbative series of these correlators. With the knowledge of the structure of renormalon singularities in the Borel transforms, we can design new observables with tamed perturbative behaviour that can lead to improved determinations of quark masses and αs based on heavy-quark current correlators.