Cabibbo angle anomalies and a global fit to vector-like quarks

The most recent determinations of $V_{ud}$ from superallowed beta decays lead to a discrepancy when compared to the value implied by mesonic CKM measurements combined with CKM unitarity. On top of this, improved precision in lattice QCD calculations have revealed another discrepancy between the $V_{us}$ determinations from kaon and pion semi-leptonic decays. The combination of these can be referred to as the Cabibbo angle anomaly, which we find has a significance of around $3\,\sigma$. After summarising the current state of these issues, I will talk about new physics models that modify semi-leptonic decays as potential explanations, and why vector-like quarks in particular appear the most promising candidates. I will then discuss the results of a global fit to various vector-like quark models, and how other constraints are important in determining the most likely explanation. Finally I will touch on future experiments that could shed further light on the situation.Comment: Prepared for the FPCP 2023 proceedings (v2: added reference

On the ultimate precision of meson mixing observables

Meson mixing is considered to be an ideal candidate for new physics searches. Current experimental precision has greatly increased over the recent years, excelling in several cases the theoretical precision. A possible limit in the theoretical accuracy could be a hypothetical breakdown of quark-hadron duality. We propose a simple model for duality violations and give stringent bounds on such effects for mixing observables, indicating regions, where future measurements of $\Delta \Gamma_d$, $a_{sl}^d$ and $a_{sl}^s$ would be clear signals of new physics. Finally, we turn our attention to the charm sector, and reveal that already a modest duality violation of about $20 \%$ could explain the huge difference between HQE predictions for D-mixing and experimental data.Comment: 37 pages, 9 figures. v2 (very belated) update to journal version (plus extended appendices

Charming New Physics in Beautiful Processes?

In this thesis we study quark flavour physics and in particular observables relating to $B$ meson mixing and lifetimes. Meson mixing arises due to the nature of the weak interaction, and leads to several related observables that are highly suppressed in the Standard Model (SM). Alongside meson mixing, lifetimes provide an insight into rare $B$ processes which can shed light on possible new physics. Both calculations are based on an Effective Field Theory (EFT) framework, in particular the Weak Effective Theory. This framework allows us to separate the high scale effects which are calculable in perturbation theory from the low energy matrix element which are determined through other means. Within this framework, the observables are expanded using the Heavy Quark Expansion (HQE) technique, which utilises the relatively large masses of $b$ and $c$ quarks to reveal a further hierarchy of corrections. The basics of EFTs and the HQE are explored in detail as an entry point to the majority of the work in this thesis. In the rest of the thesis, we take aim at pushing the accuracy of our SM predictions further: by testing the underlying assumption of Quark-Hadron duality in the HQE; by studying possible new physics models that can explain the long standing problem of dark matter as well as recently seen anomalies; and by using alternative approaches to determining the low energy constants associated with mixing and lifetimes in order to provide independent and state-of-the-art results

Microbiology for Earth Scientists

Microorganisms are the most abundant form of life on Earth and in recent decades it has become increasingly clear that their collective activities are one of the dominant forces shaping the Earth. This book provides earth scientists with an introduction to microbiology and a look at the ways microorganisms are important to their area of expertise. The first part of this book summarizes some basic information about microorganisms, including a discussion of their diversity, physical properties, and metabolisms. From there, the second and third portions of the book are organized around the two-way interactions between microorganisms and their environments. The second portion of the book considers the ways that environmental conditions help determine distributions of microbial activity, including chapters focused on thermodynamic, kinetic, and biological factors. The third and final portion of the book examines the impacts of microbes on their environments. These impacts are placed within the context of earth system science, with chapters focused on impacts to the lithosphere, atmosphere, and hydrosphere. In these chapters, emphasis is placed on microbial impacts to greenhouse gas levels and the quality of water resources, underscoring the relevance of microbiology to environmental concerns of keen interest in the earth science community and beyond. This book is specifically designed for earth science students and can provide a helpful free resource for students in Geomicrobiology courses. However, portions of the book can also have value for students and professionals from any field who are interested in environmental microbiology.https://newprairiepress.org/ebooks/1053/thumbnail.jp