Higgs production via weak boson fusion in the Standard Model and the MSSM

Higgs production via weak boson fusion (WBF) is an interesting and important process at both the LHC and a future linear collider. Not only is it a possible Higgs discovery channel, but it also allows us to study the properties of the Higgs boson and the mechanism of electroweak symmetry breaking. In this thesis this process is studied in detail for both the LHC and a future linear collider. Results for light Higgs production via vector boson fusion at a linear collider, taking the Higgsstrahlung contribution into account, are obtained in the (s)fermion sector of the Standard Model and the MSSM. Complete one loop results for weak boson fusion at the LHC in the Standard Model are presented. These include the effects of photon radiation and the full virtual electroweak corrections, as well as the QCD corrections (the latter are well known in the literature and have been taken from the code \tt VBFNLO \rm in this work). The electroweak corrections are found to be as important as the QCD corrections after the application of appropriate cuts -- they are $\sim \mathcal{O}(-5 \%)$ in the Higgs mass range of 100--200 GeV. We present the dominant supersymmetric one loop corrections to neutral Higgs production, in the general case where the MSSM includes complex phases. These results are supplemented by all one loop corrections of Standard Model type and by the propagator type corrections from the Higgs sector of the MSSM, taking the dominant two loop contributions into account. In this way the most complete available result for weak boson fusion Higgs production in the MSSM is achieved. In the decoupling region, $M_A \gg M_Z$, where the light MSSM Higgs boson becomes Standard Model like, the difference between the MSSM loop corrections and those in the Standard Model (for an equivalent Higgs mass) are, as expected, relatively small -- generally $\mathcal{O}(-0.5 \%)$. Larger SUSY loop corrections occur for the light Higgs in the non-decoupling regime -- in the $M_{h}^{max}$ scenario we see differences of $\sim \mathcal{O}(-5\%)$ between the total SM and MSSM loop corrections, and in the CPX scenario, differences of $\mathcal{O}(-5\%)$ are seen in the (s)fermion sector. In some regions of parameter space, production of the heavy MSSM Higgs boson is dominant, and in these regions loop corrections range between $\sim \pm 5\%$. Our results have been implemented into the public Monte Carlo program \tt VBFNLO\rm, which should serve as a useful tool for performing experimental analyses. We make use of an effective Higgs coupling as a simple (and computationally efficient) method of including the Higgs vertex corrections, while the Standard Model type box and pentagon diagrams are incorporated in the standard way using squared matrix elements. Finally, we also present parton level studies of (s)fermion corrections to Z boson production via weak boson fusion, in both the Standard Model and the MSSM. This process has the potential to be used in order to ``calibrate'' WBF Higgs production. Corrections to Z production are generally smaller than those to Higgs production, and are typically $\sim -0.8\%$

Heavy MSSM Higgs production at the LHC and decays to WW,ZZ at higher orders

In this paper we discuss the production of a heavy scalar MSSM Higgs boson H and its subsequent decays into pairs of electroweak gauge bosons WW and ZZ. We perform a scan over the relevant MSSM parameters, using constraints from direct Higgs searches and several low-energy observables. We then compare the possible size of the pp -> H -> WW,ZZ cross sections with corresponding Standard Model cross sections. We also include the full MSSM vertex corrections to the H -> WW,ZZ decay and combine them with the Higgs propagator corrections, paying special attention to the IR-divergent contributions. We find that the vertex corrections can be as large as -30% in MSSM parameter space regions which are currently probed by Higgs searches at the LHC. Once the sensitivity of these searches reaches two percent of the SM signal strength the vertex corrections can be numerically as important as the leading order and Higgs self-energy corrections and have to be considered when setting limits on MSSM parameters

A return to in-person public engagement at STFC

Since 2020, UKRI/STFC’s Scientific Computing Department (SCD) have developed several remote-first public engagement activities, drawing on its long and rich history of delivering face to face public engagement and outreach, as part of the wider STFC programme. With COVID19 restrictions lifted in the UK, STFC has been able to resume in-person public engagement, both on site and in public places. However, this has not meant a complete return to exclusively in-person engagement, but rather, recognising the clear benefits of remote engagement to meeting our strategic public engagement aims, STFC has produced a blended programme for 2022/23, with a mixture of in-person, remote and hybrid events. This paper presents how the remote activities have evolved since their initial creation, how the remote activities have become part of a blended programme and how the in-person activities in place since before the pandemic have been improved as a result of developing the remote activities

Pathogens and host immunity in the ancient human oral cavity.

Calcified dental plaque (dental calculus) preserves for millennia and entraps biomolecules from all domains of life and viruses. We report the first, to our knowledge, high-resolution taxonomic and protein functional characterization of the ancient oral microbiome and demonstrate that the oral cavity has long served as a reservoir for bacteria implicated in both local and systemic disease. We characterize (i) the ancient oral microbiome in a diseased state, (ii) 40 opportunistic pathogens, (iii) ancient human-associated putative antibiotic resistance genes, (iv) a genome reconstruction of the periodontal pathogen Tannerella forsythia, (v) 239 bacterial and 43 human proteins, allowing confirmation of a long-term association between host immune factors, 'red complex' pathogens and periodontal disease, and (vi) DNA sequences matching dietary sources. Directly datable and nearly ubiquitous, dental calculus permits the simultaneous investigation of pathogen activity, host immunity and diet, thereby extending direct investigation of common diseases into the human evolutionary past

Public Engagement in a Global Pandemic

UKRI/STFC’s Scientific Computing Department (SCD) has a long and rich history of delivering face to face public engagement and outreach, both on site and in public places, as part of the wider STFC programme. Due to the global COVID-19 pandemic, SCD was forced to abandon an extensive planned programme of public engagement, alongside altering the day-to-day working methods of the majority of its staff. SCD had to respond rapidly to create a new, remote only, programme for the summer and for the foreseeable future. This was initially an exercise in improvisation, identifying existing activities that could be delivered remotely with minimal changes. As the pandemic went on, SCD also created new resources specifically for a remote audience and adapted existing activities where appropriate, using our evaluation framework to ensure these activities continued to meet the aims of the in-person programme. This paper presents the process through which this was achieved, some of the benefits and challenges of remote engagement and the plans for 2021 and beyond

Higgs Production via Weak Boson Fusion in the Standard Model and the MSSM

Weak boson fusion is expected to be an important Higgs production channel at the LHC. Complete one-loop results for weak boson fusion in the Standard Model have been obtained by calculating the full virtual electroweak corrections and photon radiation and implementing these results into the public Monte Carlo program VBFNLO which includes the NLO QCD corrections. Furthermore the dominant supersymmetric one-loop corrections to neutral Higgs production, in the general case where the MSSM includes complex phases, have been calculated. These results have been combined with all one-loop corrections of Standard Model type and with the propagator-type corrections from the Higgs sector of the MSSM up to the two-loop level. Within the Standard Model the electroweak corrections are found to be as important as the QCD corrections after the application of appropriate cuts. The corrections yield a shift in the cross section of order 5% for a Higgs of mass 100-200 GeV, confirming the result obtained previously in the literature. For the production of a light Higgs boson in the MSSM the Standard Model result is recovered in the decoupling limit, while the loop contributions from superpartners to the production of neutral MSSM Higgs bosons can give rise to corrections in excess of 10% away from the decoupling region.Weak boson fusion is expected to be an important Higgs production channel at the LHC. Complete one-loop results for weak boson fusion in the Standard Model have been obtained by calculating the full virtual electroweak corrections and photon radiation and implementing these results into the public Monte Carlo program VBFNLO which includes the NLO QCD corrections. Furthermore the dominant supersymmetric one-loop corrections to neutral Higgs production, in the general case where the MSSM includes complex phases, have been calculated. These results have been combined with all one-loop corrections of Standard Model type and with the propagator-type corrections from the Higgs sector of the MSSM up to the two-loop level. Within the Standard Model the electroweak corrections are found to be as important as the QCD corrections after the application of appropriate cuts. The corrections yield a shift in the cross section of order 5% for a Higgs of mass 100-200 GeV, confirming the result obtained previously in the literature. For the production of a light Higgs boson in the MSSM the Standard Model result is recovered in the decoupling limit, while the loop contributions from superpartners to the production of neutral MSSM Higgs bosons can give rise to corrections in excess of 10% away from the decoupling region

Second asymptomatic carotid surgery trial (ACST-2) : a randomised comparison of carotid artery stenting versus carotid endarterectomy

Background: Among asymptomatic patients with severe carotid artery stenosis but no recent stroke or transient cerebral ischaemia, either carotid artery stenting (CAS) or carotid endarterectomy (CEA) can restore patency and reduce long-term stroke risks. However, from recent national registry data, each option causes about 1% procedural risk of disabling stroke or death. Comparison of their long-term protective effects requires large-scale randomised evidence. Methods: ACST-2 is an international multicentre randomised trial of CAS versus CEA among asymptomatic patients with severe stenosis thought to require intervention, interpreted with all other relevant trials. Patients were eligible if they had severe unilateral or bilateral carotid artery stenosis and both doctor and patient agreed that a carotid procedure should be undertaken, but they were substantially uncertain which one to choose. Patients were randomly allocated to CAS or CEA and followed up at 1 month and then annually, for a mean 5 years. Procedural events were those within 30 days of the intervention. Intention-to-treat analyses are provided. Analyses including procedural hazards use tabular methods. Analyses and meta-analyses of non-procedural strokes use Kaplan-Meier and log-rank methods. The trial is registered with the ISRCTN registry, ISRCTN21144362. Findings: Between Jan 15, 2008, and Dec 31, 2020, 3625 patients in 130 centres were randomly allocated, 1811 to CAS and 1814 to CEA, with good compliance, good medical therapy and a mean 5 years of follow-up. Overall, 1% had disabling stroke or death procedurally (15 allocated to CAS and 18 to CEA) and 2% had non-disabling procedural stroke (48 allocated to CAS and 29 to CEA). Kaplan-Meier estimates of 5-year non-procedural stroke were 2·5% in each group for fatal or disabling stroke, and 5·3% with CAS versus 4·5% with CEA for any stroke (rate ratio [RR] 1·16, 95% CI 0·86-1·57; p=0·33). Combining RRs for any non-procedural stroke in all CAS versus CEA trials, the RR was similar in symptomatic and asymptomatic patients (overall RR 1·11, 95% CI 0·91-1·32; p=0·21). Interpretation: Serious complications are similarly uncommon after competent CAS and CEA, and the long-term effects of these two carotid artery procedures on fatal or disabling stroke are comparable