Boosted Higgs →bbˉ\rightarrow b\bar{b} in vector-boson associated production at 14 TeV

The production of the Standard Model Higgs boson in association with a vector boson, followed by the dominant decay to $H \rightarrow b\bar{b}$, is a strong prospect for confirming and measuring the coupling to $b$-quarks in $pp$ collisions at $\sqrt{s}=14$ TeV. We present an updated study of the prospects for this analysis, focussing on the most sensitive highly Lorentz-boosted region. The evolution of the efficiency and composition of the signal and main background processes as a function of the transverse momentum of the vector boson are studied covering the region $200-1000$ GeV, comparing both a conventional dijet and jet substructure selection. The lower transverse momentum region ($200-400$ GeV) is identified as the most sensitive region for the Standard Model search, with higher transverse momentum regions not improving the statistical sensitivity. For much of the studied region ($200-600$ GeV), a conventional dijet selection performs as well as the substructure approach, while for the highest transverse momentum regions ($> 600$ GeV), which are particularly interesting for Beyond the Standard Model and high luminosity measurements, the jet substructure techniques are essential.Comment: 13 pages.(Fixed figure layout error

Public Art Advancing Urban Context Transformations: Kreuzberg (Berlin)

The proposed article focuses on an analysis of Berlin as a model for urban intervention, with proposals, both for the urban rehabilitation and for new works. The central district of Kreuzberg, will be studied taking into account that it is nowadays a place of artistic and bohemian focus, considered an integral part of the one of the main enclaves of power and culture in Europe. Local characterization will be carried out from the point of view of urban development and sociocultural transformation, as well as the artistic manifestations that are evident in public space, such as graffiti, which modify a surrounding urban space, either permanently or temporarily. Finally, in a logic of zooming on the city, a proposal will be presented for an urban void in a block at Kreuzberg east neighbourhood, which is associated with several manifestations against the gentrification processes therein. Throughout this study, it should be noted that it is still currently a challenge to define measures for the benefit of its inhabitants, leading the city in a direction that is advantageous and enriching for all, not yielding to economic interests of speculation. Therefore, an urban revitalization can and must motivate creative interventions in relation to public art, making way for the new urban planning models in city centres, pointing to more free and connected alternative lifestyles.info:eu-repo/semantics/publishedVersio

Differentiable Vertex Fitting for Jet Flavour Tagging

We propose a differentiable vertex fitting algorithm that can be used for secondary vertex fitting, and that can be seamlessly integrated into neural networks for jet flavour tagging. Vertex fitting is formulated as an optimization problem where gradients of the optimized solution vertex are defined through implicit differentiation and can be passed to upstream or downstream neural network components for network training. More broadly, this is an application of differentiable programming to integrate physics knowledge into neural network models in high energy physics. We demonstrate how differentiable secondary vertex fitting can be integrated into larger transformer-based models for flavour tagging and improve heavy flavour jet classification.Comment: 11 page

Vaccine effectiveness against symptomatic SARS-CoV-2 infection in adults aged 65 years and older in primary care: I-MOVE-COVID-19 project, Europe, December 2020 to May 2021

I-MOVE-COVID-19 primary care study team (in addition to authors above): Nick Andrews, Jamie Lopez Bernal, Heather Whitaker, Caroline Guerrisi, Titouan Launay, Shirley Masse, Sylvie van der Werf, Vincent Enouf, John Cuddihy, Adele McKenna, Michael Joyce, Cillian de Gascun, Joanne Moran, Ana Miqueleiz, Ana Navascués, Camino Trobajo-Sanmartín, Carmen Ezpeleta, Paula López Moreno, Javier Gorricho, Eva Ardanaz, Fernando Baigorria, Aurelio Barricarte, Enrique de la Cruz, Nerea Egüés, Manuel García Cenoz, Marcela Guevara, Conchi Moreno-Iribas, Carmen Sayón, Verónica Gomez, Baltazar Nunes, Rita Roquete, Adriana Silva, Aryse Melo, Inês Costa, Nuno Verdasca, Patrícia Conde, Diogo FP Marques, Anna Molesworth, Leanne Quinn, Miranda Leyton, Selin Campbell, Janine Thoulass, Jim McMenamin, Ana Martínez Mateo, Luca Basile, Daniel Castrillejo, Carmen Quiñones Rubio, Concepción Delgado-Sanz, Jesús Oliva.The I-MOVE-COVID-19 network collates epidemiological and clinical information on patients with coronavirus disease (COVID-19), including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virological characterisation in 11 European countries [1]. One component of I-MOVE-COVID-19 is the multicentre vaccine effectiveness (VE) study at primary care/outpatient level in nine European study sites in eight countries. We measured overall and product-specific COVID-19 VE against symptomatic SARS-CoV-2 infection among those aged 65 years and older. We also measured VE by time since vaccination.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101003673.info:eu-repo/semantics/publishedVersio

Searching for the Higgs boson in the bbˉb\bar{b} decay channel with the ATLAS experiment

The discovery of the Higgs boson by the ATLAS and CMS experiments is one of the main results of Run 1 of the Large Hadron Collider. However, clear evidence for the Higgs boson decay to a pair of $b$-quarks has not been observed and is crucial to establish the nature of the new found particle. The work presented in this thesis focuses on the search for the Higgs boson in the \VHbb channel, where it is produced in association with a leptonically decaying vector boson ($W$, $Z$), and decays to a pair of $b$-quarks. Prior to the start of LHC operations, the challenges posed by a $pp$ collider to a \Hbb search motivated the development of jet substructure techniques. The boosted regime plays a vital role in the sensitivity of a \VHbb search and the topologies where the decay products merge can be recovered by implementing a substructure-based selection. The sensitivity of such an approach in a \VHbb search is studied using ATLAS $pp$ collision data, at a centre-of-mass energy of \sS. It was found that the sensitivity in the boosted region of the \VHbb channel in Run 1 is already fully exploited by the resolved approach. The mass of the Higgs boson, the energies and luminosities delivered and the good performance of \akt jets resulted in little or no gain, at this stage, from performing a jet substructure analysis. The final ATLAS \VHbb Run 1 result is presented. The systematic uncertainties related to the \Wbb process are estimated and discussed. As an irreducible background to this search, the description of \Wbb events plays an important role on the final obtained sensitivity. Finally, in preparation for Run 2 and future colliders, the potential benefits from jet substructure techniques are reviewed at different centre-of-mass energies in the context of a boosted \WHbb search. A detailed study of the signal significance as a function of the boost of the system reveals that the region of highest sensitivity is already fully exploited by the resolved reconstruction. A substructure approach is only beneficial in events with boosts greater than \mbox{600 GeV}, outside the phase-space region of maximum significance

Study of ATLAS sensitivity to the single top Wt-channel cross section

The sensitivity of the ATLAS experiment, on the LHC, to the measurement of the single top Wt-channel cross section was studied. The full simulation (FullSim) of the detector was used at a centre-of-mass energy of √s = 7 TeV. Signal events and some background processes were generated using MC@NLO generator. Other background processes were generated using ALPGEN (for example W +jets) or HERWIG. A sequential and a discriminant analysis were developed for a luminosity of 200pb−1 to distinguish between signal and background events. From the results obtained, the cross section of the Wt-channel was calculated as well as its statistical uncertainty

Study of ATLAS sensitivity to the single top Wt-channel cross section

Realizou-se o estudo da sensibilidade da experiência ATLAS, do LHC, à medida da secção eficaz do canal Wt de single top. Para tal, utilizou-se a simulação completa do detector (FullSim) a uma energia de centro de massa de √s = 7 TeV. Os acontecimentos de sinal e de alguns processos de fundo foram gerados pelo gerador MC@NLO. Outros processos de fundo foram gerados através do gerador ALPGEN (ex.: W+jactos) ou HERWIG. Foi desenvolvida uma análise sequencial e discriminante para distinguir o sinal e o fundo existentes, a uma luminosidade de 200 pb−1. Com os resultados obtidos foi calculada a secção eficaz do canal Wt de single top e a respectiva incerteza estatístic

High-dimensional anomaly detection with radiative return in e+e− collisions

Abstract Experiments at a future e+e− collider will be able to search for new particles with masses below the nominal centre-of-mass energy by analyzing collisions with initial-state radiation (radiative return). We show that machine learning methods that use imperfect or missing training labels can achieve sensitivity to generic new particle production in radiative return events. In addition to presenting an application of the classification without labels (CWoLa) search method in e+e− collisions, our study combines weak supervision with variable-dimensional information by deploying a deep sets neural network architecture. We have also investigated some of the experimental aspects of anomaly detection in radiative return events and discuss these in the context of future detector design