Rare strange to down quark transitions from lattice quantum chromodynamics

In the search for new physics beyond the Standard Model (SM) of particle physics, one promising set of probes are rare decays, due to the possibility of large contributions from new physics relative to their SM prediction. Two examples of such processes are the long distance dominated avour-changing neutral current decays K⁺ → π⁺l⁺l⁻ and Σ⁺ → pl⁺l⁻, referred to as the rare kaon and rare hyperon decays respectively. These processes contain the transition of a strange quark into a down quark which can only occur at loop level within the SM, however tree level contributions could exist from physics beyond the SM. Currently, the only known method for making ab initio calculations of low energy hadronic quantities such as these, is through the use of Lattice Quantum Chromodynamics (LQCD) where correlation functions are computed numerically via Monte Carlo methods on a discrete, nite and Euclidean space-time lattice. Work from this PhD has contributed to a calculation of the rare kaon decay at physical pion mass. We then investigate an alternative method utilising directly integrated correlation functions in an attempt to reduce the large computational cost of this and similar calculations. In addition, we present work extending the existing theoretical framework for computing the rare kaon decay using LQCD to the rare hyperon decay, including the handling of exponentially growing intermediate states and the correction of power-like fi nite volume effects. We also present the current status of the fi rst exploratory calculation of the form factors of this decay with unphysically heavy pions and 2+1 flavours of domain wall fermions. In order to perform this work, multiple developments have been made to the Grid and Hadrons C++ libraries, which are open-source tools for performing large scale lattice fi eld theory calculations on both CPU and GPU based machines

Prospects for a lattice calculation of the rare decay Σ+→pℓ+ℓ−\Sigma^+\to p\ell^+\ell^-

We present a strategy for calculating the rare decay of a $\Sigma^+ (uus)$ baryon to a proton $(uud)$ and di-lepton pair using lattice QCD. To determine this observable one needs to numerically evaluate baryonic two-, three-, and four-point correlation functions related to the target process. In particular, the four-point function arises from the insertion of incoming and outgoing baryons, together with a weak Hamiltonian mediating the $s \to d$ transition and an electromagnetic current creating the outgoing leptons. As is described in previous work in other contexts, this four-point function has a highly non-trivial relation to the physical observable, due to nucleon and nucleon-pion intermediate states. These lead to growing Euclidean time dependence and, in the case of the nucleon-pion states, to power-like volume effects. We discuss how to treat these issues in the context of the $\Sigma^+\rightarrow p\ell^+\ell^-$ decay and, in particular, detail the relation between the finite-volume estimator and the physical, complex-valued amplitude. In doing so, we also make connections between various approaches in the literature

Refugee Integration Outcomes cohort study: Evidence for policy and planning

Evidence on refugee integration outcomes in the UK is lacking, partly due to an absence of datasets which permit refugees to be identified. The RIO longitudinal cohort study designed in collaboration with the Home Office aims to address this by linking administrative data longitudinally. RIO covers cohorts granted asylum and refugees resettled in England & Wales via the Vulnerable Persons and Vulnerable Children’s resettlement Schemes between 2015 and 2020. Linked data include the Personal Demographics Service from the NHS and Exit Checks from the Home Office. Census 2021 data have also been linked to the study. Deterministic linkage algorithms addressed different naming conventions across a wide set of cultures and administrative data quality. Associative linkage methods were developed to match residuals from the deterministic stage to their corresponding household if present. We conducted our own internal quality analysis to assess the quality of our linkage algorithms to improve our methodology ahead of incorporating new administrative data such as HMRC and DWP data. Experimental analysis has looked at social and economic outcomes for these refugee cohorts. Linkage to NHS data helps us understand access to health services and time taken to access these services once resettled. Census 2021 data provide a rich understanding of integration outcomes up to 6 years after arrival or grant of asylum. We demonstrate the potential of linked census data to provide evidence on housing, education, health, access to the labour market, education, households and secondary migration but also how this varies for asylum and refugee cohorts but also by age, sex and geographical region. RIO is aligned to the ONS strategic objective of inclusivity and recommendations made by the UK National Statistician’s Inclusive Data Task Force. RIO will ultimately help inform local authorities, government, charities and other organisations with resource allocation for these vulnerable populations. We are planning to make this dataset available to Accredited Researchers via the ONS Secure Research Service and the Integrated Data Service (IDS)

Isospin-breaking corrections to light leptonic decays in lattice QCD+QED at the physical point

We report on the physical-point RBC/UKQCD calculation of the leading isospin-breaking corrections to light-meson leptonic decays. This is highly relevant for future precision tests in the flavour physics sector, in particular the first-row unitarity of the Cabibbo-Kobayashi-Maskawa matrix containing the elements $V_{us}$ and $V_{ud}$. The simulations were performed using Domain-Wall fermions for $2+1$ flavours, and with isospin-breaking effects included perturbatively in the path integral through order $\alpha$ and $(m_u - m_d)/\Lambda _{\mathrm{QCD}}$. We use QED$_{\mathrm{L}}$ for the inclusion of electromagnetism, and discuss here the non-locality of this prescription which has significant impact on the infinite-volume extrapolation.Comment: Proceedings for The 39th International Symposium on Lattice Field Theory, 8th-13th August, 2022, Rheinische Friedrich-Wilhelms-Universit\"at Bonn, Bonn, German

Risk, risk factors and surveillance of subsequent malignant neoplasms in childhood cancer survivors: a review

Subsequent malignant neoplasms (SMNs) in childhood cancer survivors cause substantial morbidity and mortality. This review summarizes recent literature on SMN epidemiology, risk factors, surveillance, and interventions. Survivors of childhood cancer experience long-term increased SMN risk compared with the general population, with a greater than twofold increased solid tumor risk extending beyond age 40 years. There is a dose-dependent increased risk for solid tumors after radiotherapy, with the highest risks for tumors occurring in or near the treatment field (eg, greater than fivefold increased risk for breast, brain, thyroid, skin, bone, and soft tissue malignancies). Alkylating and anthracycline chemotherapies increase the risk for development of several solid malignancies in addition to acute leukemia/myelodysplasia, and these risks may be modified by other patient characteristics, such as age at exposure and, potentially, inherited genetic susceptibility. Strategies for identifying survivors at risk and initiating long-term surveillance have improved and interventions are underway to improve knowledge about late-treatment effects among survivors and caregivers. Better understanding of treatment-related risk factors and genetic susceptibility holds promise for refining surveillance strategies and, ultimately, upfront cancer therapies

Prospects for a lattice calculation of the rare decay Σ+ → pℓ + ℓ −

Abstract We present a strategy for calculating the rare decay of a Σ+(uus) baryon to a proton (uud) and di-lepton pair using lattice QCD. To determine this observable one needs to numerically evaluate baryonic two-, three-, and four-point correlation functions related to the target process. In particular, the four-point function arises from the insertion of incoming and outgoing baryons, together with a weak Hamiltonian mediating the s → d transition and an electromagnetic current creating the outgoing leptons. As is described in previous work in other contexts, this four-point function has a highly non-trivial relation to the physical observable, due to proton and proton-pion intermediate states. These lead to growing Euclidean time dependence and, in the case of the two-particle intermediate states, to power-like volume effects. We discuss how to treat these issues in the context of the Σ+ → pℓ + ℓ − decay and, in particular, detail the relation between the finite-volume estimator and the physical, complex-valued amplitude. In doing so, we also make connections between various approaches already described in the literature

Near Physical Point Lattice Calculation of Isospin-Breaking Corrections to Kℓ2/πℓ2K_{\ell2}/\pi_{\ell2}

In recent years, lattice determinations of non-perturbative quantities such as $f_K$ and $f_\pi$, which are relevant for $V_{us}$ and $V_{ud}$, have reached an impressive precision of $\mathcal{O}(1\%)$ or better. To make further progress, electromagnetic and strong isospin breaking effects must be included in lattice QCD simulations. We present the status of the RBC\&UKQCD lattice calculation of isospin-breaking corrections to light meson leptonic decays. This computation is performed in a (2+1)-flavor QCD simulation using Domain Wall Fermions with near-physical quark masses. The isospin-breaking effects are implemented via a perturbative expansion of the action in $\alpha$ and $(m_u-m_d)$. In this calculation, we work in the electro-quenched approximation and the photons are implemented in the Feynman gauge and $\text{QED}_\text{L}$ formulation.In recent years, lattice determinations of non-perturbative quantities such as $f_K$ and $f_\pi$, which are relevant for $V_{us}$ and $V_{ud}$, have reached an impressive precision of $\mathcal{O}(1\%)$ or better. To make further progress, electromagnetic and strong isospin breaking effects must be included in lattice QCD simulations. We present the status of the RBC/UKQCD lattice calculation of isospin-breaking corrections to light meson leptonic decays. This computation is performed in a (2+1)-flavor QCD simulation using Domain Wall Fermions with near-physical quark masses. The isospin-breaking effects are implemented via a perturbative expansion of the action in $\alpha$ and $(m_u-m_d)$. In this calculation, we work in the electro-quenched approximation and the photons are implemented in the Feynman gauge and $\text{QED}_\text{L}$ formulation

Near-physical point lattice calculation of isospin-breaking corrections to Kℓ2/πℓ2

In recent years, lattice determinations of non-perturbative quantities such as fK and fπ, which are relevant for Vus and Vud, have reached an impressive precision of O(1%) or better. To make further progress, electromagnetic and strong isospin breaking effects must be included in lattice QCD simulations.We present the status of the RBC/UKQCD lattice calculation of isospin-breaking corrections to light meson leptonic decays. This computation is performed in a (2+1)-flavor QCD simulation using Domain Wall Fermions with near-physical quark masses. The isospin-breaking effects are implemented via a perturbative expansion of the action in α and (mu−md). In this calculation, we work in the electro-quenched approximation and the photons are implemented in the Feynman gauge and QEDL formulation

Lattice dataset for the paper arXiv:2202.08795 "Simulating rare kaon decays using domain wall lattice QCD with physical light quark masses"

Release for https://arxiv.org/abs/2202.08795</span