Heavy to light meson decay form factors

Roberts, Logan Sean (2026) Heavy to light meson decay form factors. PhD thesis, University of Glasgow.

Abstract

This thesis presents our progress on using lattice Quantum Chromodynamics to calculate scalar, vector, and tensor kinematic form factors for the following semileptonic meson decays: 𝐵 →π, 𝐵ₛ →𝐾, 𝐷→π and 𝐷ₛ →𝐾. These meson decays include the quark transitions 𝑏→𝑢 or 𝑐→𝑑, whose amplitudes are parameterized by elements of the Cabibbo-Kobayashi-Maskawa (CKM) matrix. Calculating scalar and vector form factors for these decays can, alongside experimentally determined differential decay rates, be used to make precise determinations of the CKM matrix elements Vᵤ₆ and V꜀ₔ. More precise CKM matrix elements have broad implications for Standard Model flavor physics, such as enabling better tests of CKM matrix unitarity. Moreover, calculating tensor form factors has implications for Standard Model-suppressed and beyond Standard Model physics. This line of lattice calculations uses the Highly Improved Staggered Quark (HISQ) formalism, and n𝑓 = 2+1+1 MILC-HISQ gluon field ensembles. Using a modified 𝓏-expansion, we succeed in calculating scalar, vector, and tensor kinematic form factors in the continuum limit for all four meson decays of interest to this work. Finally we compare our 𝑞² = 0 and 𝑞² = 𝑞²ₘₐₓ form factor results to those of other relevant works.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: Q Science > QB Astronomy; Q Science > QC Physics
• Colleges/Schools: College of Science and Engineering > School of Physics and Astronomy
• Supervisor's Name: Bouchard, Dr. Chris and Renner, Dr. Sophie
• Date of Award: 2026
• Depositing User: Theses Team
• Unique ID: glathesis:2026-86232
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 10 Sep 2026 13:54
• Last Modified: 10 Sep 2026 13:56
• Thesis DOI: 10.5525/gla.thesis.86232
• URI: https://theses.gla.ac.uk/id/eprint/86232