ttˉ+Vt\bar{t}+V production in ATLAS

The latest ATLAS results for processes with a top quark pair and an associated vector boson are presented here. The measurement of the production cross sections for these processes is important for the direct determination of the top quark couplings to gauge bosons and for constraints on new physics models, in particular for models which go beyond the Standard Model regarding the mechanism for the mass generation.Comment: 5 pages, conference TOP201

Measurements of inclusive and differential fiducial cross-sections of ttˉγt\bar{t}\gamma production in leptonic final states at s\sqrt{s} = 13 TeV

The latest results of the ATLAS experiment for the production of a top-quark pair in association with a photon using proton-proton collision data from the LHC at a centre-of-mass energy of 13 TeV are summarised here. This includes inclusive and differential cross-sections measurements performed in single-lepton and dilepton final states in a fiducial volume corresponding to the experimental acceptance.Comment: TOP2018 conference, 5 page

Search for CP violation in single top quark events with the ATLAS detector at LHC

The elementary particles, their properties and their interactions are described by the SM, which is the theoretical framework constructed for the study of the strong interactions of quarks and gluons and the unified electroweak force and that is based on local gauge invariance. The SM is very successful in giving account of most of the observed phenomena at the microscopic frontier of physics, having been verified and tested in many experiments in the last decades. The SM has also induced the search of novel phenomena, such as the recent discovery of the Higgs boson by the ATLAS and CMS experiments at the LHC. Despite these spectacular successes, there are evidences that the theory cannot be complete since, besides some possible theoretical diseases (the hierarchy problem), it is unable to explain some observed phenomena in nature. First of all, it does not include gravity and its constituents can only account for around 5% of the energy-matter content of our universe and no SM particle can be a candidate to describe dark matter. Furthermore, the observation of neutrino oscillations implies neutrino mass and mixing, incompatible with the minimal version of the SM. And, in addition, the standard flavour physics framework for CP violation, the mismatch between weak interaction and mass eigenstates of quarks by means of the CKM mixing matrix, is unable to explain the baryon asymmetry of the universe by many orders of magnitude. Although precision experiments in the K and B meson facilities agree with the predictions of the SM, new physics sources of CP violation are unavoidable. With all this, it is clear that extensions of the SM are needed. New physics models that modify the SM in ways subtle enough to be consistent with existing data are being proposed. In this thesis, an extension of the SM with additional sources of CP violation in the top quark sector is proposed. The top quark decays almost exclusively into a b quark and a W boson via the weak interaction, thus it allows to probe the chiral structure of the W-t-b interaction. The Wtb vertex can be parametrised with using an effective Lagrangian approach including the couplings VL, VR, gL ad gR (left- and right-handed vector and tensor couplings) which are in general complex. At tree level in the SM, the coupling VL is given by the CKM matrix element Vtb and is therefore almost equal to one, while the other three couplings (so-called anomalous couplings) vanish, leading to the pure vector minus axial structure of the weak interaction in the SM. Although non-vanishing values of the right-handed coupling VR and of the tensor couplings gR and gL are not forbidden, several constraints on these anomalous couplings exist from both indirect observations and direct measurements. Deviations from the expected values can be probed by measuring the W polarisation fractions or angular asymmetries in the decay products of top quarks. Indeed, the W helicity fractions measured in top quark pairs events have allowed to set limits to the real part of the anomalous couplings VR, gL and gR. However, they are not sensitive to their complex phases which would imply that the top quark decay has a CP-violating component. For unpolarised top quark production the only meaningful reference direction in the top quark rest frame is the momentum q of the W boson (or -q of the b quark). However for polarised top quarks, such as those produced via electroweak interactions, one can also exploit the spin direction given by st. From these two directions, further references can be defined normal N and transverse T to the plane formed by the W boson momentum direction q and the top quark spin direction st. In a similar way that the helicity angle theta* is defined between the lepton in the W boson rest frame and the W boson momentum, the angles N and T are defined between the lepton and these new directions. In addition, two further sets of W boson polarisation fractions can be defined. The most interesting remark is that the normal set of polarisation fractions (FN+, FN0 and FN-) depend on the imaginary part of the anomalous coupling gR; so observables depending on these will deserve special attention. If CP is conserved in the Wtb vertex, i.e. if all anomalous couplings are real, then FN+ = FN-. A net normal W polarisation (FN+, FN-) can only be produced if CP is violated in the t->Wb decay. This property is unique of the normal direction and is here explored in the decay of polarised top quarks produced through electroweak interaction in proton-proton collisions at the LHC. The measurement of this forward-backward asymmetry AFBN (using t-channel single top quark events) is the major contribution of this thesis. The full 7 TeV dataset collected by the ATLAS detector in 2011 has been analyzed, which corresponds to an integrated luminosity of 4.66 fb-1. Events with an isolated electron or muon, missing transverse momentum and two jets being one tagged as a b-jet have been selected in this analysis. A full reconstruction of the top quark from its decay products is required to define the angle N. In order to understand the modelling of the t-channel single top quark events provided by Monte Carlo generators, studies of the kinematic properties of the final state particles have been conducted and di erent event generators have been compared. A special emphasis has been devoted to determine the W+jets background, that constitutes the dominant background contribution. An in-situ technique has been employed using data events in control regions in order to estimate the number of events of this background in the analysed dataset. Other processes such as multijet events are also estimated with dedicated data-driven methods. Finally, top quark background processes and diboson and Z+jets production are determined from Monte Carlo simulations. A cut-based strategy is followed exploiting the properties of the signal events. The final signal-to-background ratio is close to one. The reconstructed distribution of cos N is affected by the acceptance cuts and detector effects. In order to allow a direct comparison of the experimental measurement with the theoretical prediction, the measured angular distribution must be unfolded, i.e. deconvoluted back to parton level (partons from the hard process). An unfolding technique by inversion of the response matrix has been applied to correct for acceptance and reconstruction e ects which are modelled using t-channel simulated events. In addition, systematic uncertainties in modelling the physics processes and detector e ects have been estimated, being the modelling of top quark processes the largest one. The final asymmetry with its statistical and systematic uncertainties is: AFBN = 0.031 +- 0.065 (stat-) +0.029-0.031 (syst.). The result is dominated by the statistical uncertainty, so improvements are expected using the full 2012 dataset at 8 TeV with four times more statistics. Using the relation between AN FB and Im(gR), it is possible to constrain the allowed regions in the top quark polarisation versus Im(gR) plane. Assuming a value of P = 0:9 for the top quark polarisation, which is the SM prediction for the single top t-channel production, the first experimental limits on Im(gR) are found to be [-0.20; 0.30] at 95% confidence level. Both the asymmetry and the limit are consistent with SM predictions. This measurement involves understanding the process at generator level, a precise determination of the background processes, applying an unfolding procedure and estimating the corresponding systematic uncertainties. At the time of writing this thesis, other analyses to probe the Wtb vertex anomalous couplings in single top quark events with the full 8 TeV dataset are being completed in ATLAS, including studies of other unfolding techniques, in addition to the one explored in this document. The combination of several observables will allow to obtain higher precision and set tighter constraints in the Wtb vertex.In order to achieve the level of accuracy and precision required in these measurements, and to be sensitive to new physics, an excellent understanding of the detector is required. Thus performance studies are crucial to properly calibrate and align the detectors, improve the reconstruction algorithms and minimize systematic uncertainties. Indeed this thesis work includes two performance studies carried out with the first ATLAS data: global cosmic-ray runs recorded during the commissioning period and first proton-proton collisions runs at 7 TeV. In the commissioning period, prior to the first collisions in 2010, millions of cosmic-ray events were recorded and reconstructed in the ATLAS detector, and allowed to test the full operation chain, including data acquisition, reconstruction and analysis software. Most of the studies were focused on understanding the performance of individual subdetectors, while in the work presented in the first part of this thesis the performance of the reconstruction of cosmic-ray muons was studied combining information of all the subdetectors (inner detector, calorimeters and muon spectrometer). The performance of the combined tracking was evaluated by comparing the two reconstructed tracks left by a single cosmic-ray muon passing through the upper and then the lower half of the detector. In addition, the track parameter resolutions were derived using information only from data. Once the LHC delivered the first collisions, the reconstruction of other final state objects could also be studied in detailed. The contribution presented here is focused on the reconstruction of jets, in particular the jet structure. The jet shapes were measured in both regions inside and outside the jet cone, and the fraction of the jet momentum left out of the cone was extracted from them. Both measurements were compared to Monte Carlo predictions. In 2015, the LHC will provide proton-proton collisions at 13-14 TeV and the detectors will resume data-taking, accessing a range of energies never studied before, and giving the opportunity for new exciting discoveries in top quark decays. These data will allow to improve the calibration and reconstruction methods, to carry out more performance studies and to improve the understanding of Monte Carlo generators, to minimize any possible systematic uncertainty and to reach the needed accuracy

Situación actual en españa de los aerosoles insecticidas registrados en sanidad ambiental para uso doméstico

Josefa Moreno Marí*, Amparo Meliá Llácer, María Teresa Oltra Moscardó y Ricardo Jiménez Peydró (*[email protected])La reciente transposición de la Directiva de Biocidas a través del Real Decreto 1.054/2002 conllevará un cambio sustancial en distintos aspectos de la Sanidad Ambiental. Para evaluar la incidencia de estos cambios se presenta un análisis de la situación actual, a partir del cual se podrán valorar adecuadamente las consecuencias de la implantación de la Directiva en España, así como establecer los aspectos básicos que se deben analizar con vistas al establecimiento de un Registro de Biocidas acorde con dicho Real Decreto

Estrategia de enseñanza y aprendizaje de programación basada en la idea de ’hackathon’

[EN] The acquisition of programming and data analysis skills in higher education is increa-singly necessary in all areas of Science and Engineering. In this paper we present a methodology for the motivation of programming learning, mainly focused on the deve-lopment of machine learning algorithms. This methodology is based on the hackathon idea and will have different levels. On the one hand the basic level where a competition is proposed in an improvised way during the development of the class. A second level where a programmed hackathon is proposed but within the classroom environment and using learning management systems such as Moodle. The last level consists of parti-cipation in an external hackathon and the delivery of a report. These levels have been adapted and tested in several undergraduate and master’s degree courses at the Uni-versity of Valencia. We include detailed information on how the methodology has been adapted to the teaching needs of the subject and we conducted anonymized surveys to students to know their degree of satisfaction. These surveys reveal a positive assessment of the experience by the students and include constructive comments for improvement in future editions.[ES] Se presenta una metodología para la motivación del aprendizaje de programación, principalmente enfocada al desarrollo de algoritmos de machine learning. Esta metodología está basada en la idea de hackathon o datathon y tendrá distintos niveles. Por un lado el nivel básico donde se plantea una competición de forma improvisada durante el desarrollo de la clase. Este nivel se puede utilizar para motivar, la evaluación tiene que restringirse a la mera participación. Un segundo nivel donde se plantea un hackathon programado pero dentro del entorno de la clase y utilizando sistemas de gestión de aprendizaje tipo Moodle. Este nivel se puede utilizar para evaluación tanto durante la clase como para un examen. El último nivel consiste en la participación en un hackathon externo y la entrega de un informe. Esta metodología puede servir para la evaluación de una tarea de clase y fomentar el trabajo en equipo. Además plantea un problema real en un entorno semi-profesional.Proyecto de innovación educativa “Explotación de las herramientas online de la Universitat de València para la evaluación a distancia de asignaturas en el área de ciencia” curso (2020-21) UV-SFPIE PID-1354708Piles, M.; Laparra Pérez-Muelas, V.; Peréz-Suay, A.; Mateo-García, G.; Girbés-Juan, V.; Moreno-Llácer, M.; Muñoz-Marí, J. (2021). Estrategia de enseñanza y aprendizaje de programación basada en la idea de ’hackathon’. En IN-RED 2021: VII Congreso de Innovación Edicativa y Docencia en Red. Editorial Universitat Politècnica de València. 1552-1564. https://doi.org/10.4995/INRED2021.2021.13785OCS1552156

Measurement of isolated-photon plus two-jet production in pp collisions at √s = 13 TeV with the ATLAS detector

The dynamics of isolated-photon plus two-jet production in pp collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset corresponding to an integrated luminosity of 36.1 fb. Cross sections are measured as functions of a variety of observables, including angular correlations and invariant masses of the objects in the final state, γ + jet + jet. Measurements are also performed in phase-space regions enriched in each of the two underlying physical mechanisms, namely direct and fragmentation processes. The measurements cover the range of photon (jet) transverse momenta from 150 GeV (100 GeV) to 2 TeV. The tree-level plus parton-shower predictions from Sherpa and Pythia as well as the next-to-leading-order QCD predictions from Sherpa are compared with the measurements. The next-to-leading-order QCD predictions describe the data adequately in shape and normalisation except for regions of phase space such as those with high values of the invariant mass or rapidity separation of the two jets, where the predictions overestimate the data. [Figure not available: see fulltext.

Flipped evaluation: herramientas online para la evaluación participativa

[EN] The evaluation of a subject is a fundamental part of the teaching-learning process and one of the main concerns of our students. This is a complex task that requires a lot of effort from the teacher. This is a growing effort in line with the increased weight of con-tinuous evaluation in the current educational system. In this work, different methodo-logies focused on maximizing the student’s performance are presented, thus minimizing the extra effort for the teacher in the evaluation process. We provide several examples of activities throught Moodle platform such as the workshop, glossary, databases, ques-tionnaires, etc. Some of them allow self-assessment once configured, whereas others promote the participation of students in the correction and/or evaluation.[ES] La evaluación de una asignatura es una parte fundamental del proceso de enseñanza-aprendizaje y una de la que más preocupa a nuestros estudiantes. Se trata de una tarea compleja y que requiere un gran esfuerzo por parte del profesor. Un mayor esfuerzo que va parejo al incremento de la evaluación continua, una tendencia en el sistema educativo actual. En este trabajo se presentan diferentes metodologías que maximizan el rendimiento del alumno, tratando a su vez de minimizar el esfuerzo extra por parte del profesor en los procesos de corrección y evaluación. Se proporcionan diversos ejemplos de su uso mediante actividades disponibles en la plataforma Moodle como: taller, glosario, bases de datos, cuestionarios aleatorios, etc. Algunas de estas herramientas permiten la autoevaluación una vez configuradas, en otros casos se presentan metodologías que implican la participación del alumnado en la corrección y/o evaluación.Proyecto de innovación educativa “Explotación de las herramientas online de la Universitat de València para la evaluación a distancia de asignaturas en el área de ciencia” del curso 2020-21 (UV-SFPIE PID-1354708)Amorós López, J.; Ruescas Orient, A.; Esperante Pereira, D.; Girbés-Juan, V.; Fernandez-Moran, R.; Moreno Llácer, M.; Peréz-Suay, A.... (2021). Flipped evaluation: herramientas online para la evaluación participativa. En IN-RED 2021: VII Congreso de Innovación Edicativa y Docencia en Red. Editorial Universitat Politècnica de València. 675-689. https://doi.org/10.4995/INRED2021.2021.13461OCS67568

Charged-particle multiplicities in pp interactions at root s=900 GeV measured with the ATLAS detector at the LHC

22 páginas, 4 figuras, 1 tabla.-- et al.(ATLAS Collaboration).-- arXiv:1003.3124v2The first measurements from proton-proton collisions recorded with the ATLAS detector at the LHC are presented. Data were collected in December 2009 using a minimum-bias trigger during collisions at a centre-of-mass energy of 900 GeV. The charged-particle multiplicity, its dependence on transverse momentum and pseudorapidity. and the relationship between mean transverse momentum and charged-particle multiplicity are measured for events with at least one charged particle in the kinematic range vertical bar eta vertical bar 500 MeV. The measurements are compared to Monte Carlo models of proton-proton collisions and to results from other experiments at the same centre-of-mass energy. The charged-particle multiplicity per event and unit of pseudorapidity eta = 0 is measured to be 1.333 +/- 0.003(stat.) +/- 0.040(syst.), which is 5-15% higher than the Monte Carlo models predict.We are greatly indebted to all CERN’s departments and to the LHC project for their immense efforts not only in building the LHC, but also for their direct contributions to the construction and installation of the ATLAS detector and its infrastructure. All our congratulations go to the LHC operation team for the superb performance during this initial data-taking period. We acknowledge equally warmly all our technical colleagues in the collaborating Institutions without whom the ATLAS detector could not have been built. Furthermore we are grateful to all the funding agencies which supported generously the construction and the commissioning of the ATLAS detector and also provided the computing infrastructure. The ATLAS detector design and construction has taken about fifteen years, and our thoughts are with all our colleagues who sadly could not see its final realisation. We acknowledge the support of ANPCyT, Argentina; Yerevan Physics Institute, Armenia; ARC and DEST, Australia; Bundesministerium für Wissenschaft und Forschung, Austria; National Academy of Sciences of Azerbaijan; State Committee on Science & Technologies of the Republic of Belarus; CNPq and FINEP, Brazil; NSERC, NRC, and CFI, Canada; CERN; CONICYT, Chile; NSFC, China; COLCIENCIAS, Colombia; Ministry of Education, Youth and Sports of the Czech Republic, Ministry of Industry and Trade of the Czech Republic, and Committee for Collaboration of the Czech Republic with CERN; Danish Natural Science Research Council and the Lundbeck Foundation; European Commission, through the ARTEMIS Research Training Network; IN2P3-CNRS and Dapnia-CEA, France; Georgian Academy of Sciences; BMBF, HGF, DFG and MPG, Germany; Ministry of Education and Religion, through the EPEAEK program PYTHAGORAS II and GSRT, Greece; ISF, MINERVA, GIF, DIP, and Benoziyo Center, Israel; INFN, Italy; MEXT, Japan; CNRST, Morocco; FOM and NWO, Netherlands; The Research Council of Norway; Ministry of Science and Higher Education, Poland; GRICES and FCT, Portugal; Ministry of Education and Research, Romania; Ministry of Education and Science of the Russian Federation and State Atomic Energy Corporation “Rosatom”; JINR; Ministry of Science, Serbia; Department of International Science and Technology Cooperation, Ministry of Education of the Slovak Republic; Slovenian Research Agency, Ministry of Higher Education, Science and Technology, Slovenia; Ministerio de Educación y Ciencia, Spain; The Swedish Research Council, The Knut and Alice Wallenberg Foundation, Sweden; State Secretariat for Education and Science, Swiss National Science Foundation, and Cantons of Bern and Geneva, Switzerland; National Science Council, Taiwan; TAEK, Turkey; The Science and Technology Facilities Council and The Leverhulme Trust, United Kingdom; DOE and NSF, United States of America.Peer reviewe

Search for resonances decaying into a weak vector boson and a Higgs boson in the fully hadronic final state produced in proton-proton collisions at s =13 TeV with the ATLAS detector

A search for heavy resonances decaying into a W or Z boson and a Higgs boson produced in proton-proton collisions at the Large Hadron Collider at s=13 TeV is presented. The analysis utilizes the dominant W→qq¯′ or Z→qq¯ and H→bb¯ decays with substructure techniques applied to large-radius jets. A sample corresponding to an integrated luminosity of 139 fb-1 collected with the ATLAS detector is analyzed and no significant excess of data is observed over the background prediction. The results are interpreted in the context of the heavy vector triplet model with spin-1 W′ and Z′ bosons. Upper limits on the cross section are set for resonances with mass between 1.5 and 5.0 TeV, ranging from 6.8 to 0.53 fb for W′→WH and from 8.7 to 0.53 fb for Z′→ZH at the 95% confidence level