Electroweak Cross-sections and Widths

The status of W and Z cross-section and width measurements from the CDF and D0 experiments is reviewed. Recent results that are discussed: the cross-section for Z production times the branching ratio to tau pairs, the rapidity and transverse momentum distributions of Z production in the electron channel, and the direct measurements of the W width and the Z invisible width; the latter from an analysis of events with large missing transverse energy and one or more energetic jets.Comment: Contribution to the Proceedings of the 34th International Conference on High Energy Physics; 4 pages, 2 figure

The CLIC Physics Potential

The physics and detector studies for the Compact Linear Collider (CLIC) are introduced. A staged programme of e+e − collisions covering √ s = 380 GeV, 1.5 TeV, and 3 TeV would allow precise measurements of Higgs boson couplings, in many cases to the percent level. This corresponds to precision higher than that expected for the high-luminosity Large Hadron Collider. Such precise Higgs coupling measurements would allow sensitivity to a variety of new physics models and the ability to distinguish between them. In addition, new particles directly produced in pairs could be measured with great precision, and measurements in the top-quark sector would provide sensitivity to new physics effects at the scales of tens of TeV

Diboson Physics at the Tevatron

Tevatron diboson measurements are reviewed, and new or recent results reported for Wgamma, Zgamma, and ZZ production in the leptonic decay modes, and for WW/WZ production in the lepton plus jets decay mode. The most stringent limits on anomalous triple gauge couplings are reported for each final state.Comment: Presented at the 2011 Hadron Collider Physics symposium (HCP-2011), Paris, France, November 14-18 2011, 5 pages, 13 figure

Microbial source tracking for the UK water industry

EngD ThesisThis thesis evaluates the suitability of two emerging microbial source tracking (MST) techniques, host-associated E. coli biomarkers and community-based MST. Previous human-associated E.coli markers (H8, H12, H14, H24) were evaluated for the first time in the UK; the sensitivity of H8 (10%) was lower than previously reported (50% (Gomi et al., 2014)) and if analysed through regulatory culture-based approaches alone, would have resulted in a high false negative rate (90%). In light of this, the Hu100 marker, with the highest abundance (2.64 x 106 gene copies/100 mL) across 14 wastewater treatment plants, was developed through interrogation of 263 E.coli genomes. The abundance of Hu100 was not significantly different to other markers, which, could be due to the large variability in the proportion of E.coli containing biomarkers. Due to this variation, it is recommend that the total marker abundance is used to compare different sites. Community-based MST uses high-throughput sequencing to compare bacterial communities of environmental samples, such as sea water, faecal taxon libraries (FTLs) which contain bacterial communities from known sources. Simulated microbial communities were used to evaluate how the composition of FTLs affected the accuracy and sensitivity of community-based MST. The inclusion of local samples appears to be more important than the size of the FTL to the accuracy of community-based MST. Furthermore, the inclusion of a river water sample as a ‘background sample’, improved method sensitivity from a 5% mixture of the sewage bacterial community in river waste to a 2% contribution of sewage. Two catchment studies highlighted the ubiquity of urban diffuse pollution, largely from septic tanks and misconnections, in rural and semi-rural catchments. Community-based MST showed a good correlation with human-associated markers and (rs >0.467, p <4.45x10-06), but only when human sources were dominant. Findings suggest that community-based MST is more useful than marker-based MST to survey catchments for a range of potential pollution sources. Investing ~£230k to perform MST in-house is the best option for Northumbrian Water, and other water companies, to incorporate qPCR and sequencing into their workflows. While >3000 samples need to be processed to achieve a return on investment, the business risk remains small, and other areas of the business will benefit from this investment.Northumbrian Water and EPSR

The Compact Linear Collider (CLIC) - 2018 Summary Report

The Compact Linear Collider (CLIC) is a TeV-scale high-luminosity linear e+e- collider under development at CERN. Following the CLIC conceptual design published in 2012, this report provides an overview of the CLIC project, its current status, and future developments. It presents the CLIC physics potential and reports on design, technology, and implementation aspects of the accelerator and the detector. CLIC is foreseen to be built and operated in stages, at centre-of-mass energies of 380 GeV, 1.5 TeV and 3 TeV, respectively. CLIC uses a two-beam acceleration scheme, in which 12 GHz accelerating structures are powered via a high-current drive beam. For the first stage, an alternative with X-band klystron powering is also considered. CLIC accelerator optimisation, technical developments and system tests have resulted in an increased energy efficiency (power around 170 MW) for the 380 GeV stage, together with a reduced cost estimate at the level of 6 billion CHF. The detector concept has been refined using improved software tools. Significant progress has been made on detector technology developments for the tracking and calorimetry systems. A wide range of CLIC physics studies has been conducted, both through full detector simulations and parametric studies, together providing a broad overview of the CLIC physics potential. Each of the three energy stages adds cornerstones of the full CLIC physics programme, such as Higgs width and couplings, top-quark properties, Higgs self-coupling, direct searches, and many precision electroweak measurements. The interpretation of the combined results gives crucial and accurate insight into new physics, largely complementary to LHC and HL-LHC. The construction of the first CLIC energy stage could start by 2026. First beams would be available by 2035, marking the beginning of a broad CLIC physics programme spanning 25-30 years

Measurement of σ(HVeVe) x BR(H→ ZZ*) and Higgs production in ZZ fusion at a 1.4 TeV CLIC collider

This paper presents the potential measurement at 1.4 TeV CLIC of the cross-section (times branching ratio) of the Higgs production via WW fusion with the Higgs subsequently decaying in ZZ⇤, s(Hnen¯e)⇥BR(H ! ZZ⇤), and of the Higgs production via ZZ fusion with the Higgs subsequently decaying in bb¯, s(He+e)⇥BR(H ! bb¯). For the H ! ZZ⇤ decay the hadronic final state, ZZ⇤ ! qqq¯ q¯, and the semi-leptonic final state, ZZ⇤ ! qql¯ +l , are considered. The results show that s(Hnen¯e)⇥BR(H ! ZZ⇤) can be measured with a precision of 18.3% and 6% for the hadronic and semi-leptonic channel, respectively. s(He+e)⇥BR(H ! bb¯) can be measured with a precision of 1.7%. This measurement also contributes to the determination of the Higgs coupling to the Z boson, gHZZInternational Workshop on Future Linear Colliders (LCWS14) : October 6-10, Belgrade, 2014

Inclusive and differential cross-section measurements of t\bartZ production in pp collisions at √s=13 TeV with the ATLAS detector, including EFT and spin-correlation interpretations

Measurements of both the inclusive and differential production cross sections of a top-quark-top-antiquark pair in association with a Z boson (tt¯Z) are presented. Final states with two, three or four isolated leptons (electrons or muons) are targeted. The measurements use the data recorded by the ATLAS detector in pp collisions at s√=13 TeV at the Large Hadron Collider during the years 2015-2018, corresponding to an integrated luminosity of 140 fb−1. The inclusive cross section is measured to be σtt¯Z=0.86±0.04 (stat.)±0.04 (syst.) pb and found to be in agreement with the most advanced Standard Model predictions. The differential measurements are presented as a function of a number of observables that probe the kinematics of the tt¯Z system. Both the absolute and normalised differential cross-section measurements are performed at particle level and parton level for specific fiducial volumes, and are compared with NLO+NNLL theoretical predictions. The results are interpreted in the framework of Standard Model effective field theory and used to set limits on a large number of dimension-6 operators involving the top quark. The first measurement of spin correlations in tt¯Z events is presented: the results are in agreement with the Standard Model expectations, and the null hypothesis of no spin correlations is disfavoured with a significance of 1.8 standard deviations

Observation of quantum entanglement in top-quark pairs using the ATLAS detector

We report the highest-energy observation of entanglement, in top−antitop quark events produced at the Large Hadron Collider, using a proton−proton collision data set with a center-of-mass energy of s√=13 TeV and an integrated luminosity of 140 fb−1 recorded with the ATLAS experiment. Spin entanglement is detected from the measurement of a single observable D, inferred from the angle between the charged leptons in their parent top- and antitop-quark rest frames. The observable is measured in a narrow interval around the top−antitop quark production threshold, where the entanglement detection is expected to be significant. It is reported in a fiducial phase space defined with stable particles to minimize the uncertainties that stem from limitations of the Monte Carlo event generators and the parton shower model in modelling top-quark pair production. The entanglement marker is measured to be D=−0.547±0.002 (stat.)±0.021 (syst.) for 340&lt;mtt¯&lt;380 GeV. The observed result is more than five standard deviations from a scenario without entanglement and hence constitutes both the first observation of entanglement in a pair of quarks and the highest-energy observation of entanglement to date