Calibration of the CMS hadron calorimeters using proton-proton collision data at root s=13 TeV

Methods are presented for calibrating the hadron calorimeter system of theCMSetector at the LHC. The hadron calorimeters of the CMS experiment are sampling calorimeters of brass and scintillator, and are in the form of one central detector and two endcaps. These calorimeters cover pseudorapidities vertical bar eta vertical bar ee data. The energy scale of the outer calorimeters has been determined with test beam data and is confirmed through data with high transverse momentum jets. In this paper, we present the details of the calibration methods and accuracy.Peer reviewe

Search for top squark pair production in a final state with two tau leptons in proton-proton collisions at root s=13 TeV

A search for pair production of the supersymmetric partner of the top quark, the top squark, in proton-proton collision events at s = 13 TeV is presented in a final state containing hadronically decaying tau leptons and large missing transverse momentum. This final state is highly sensitive to high-tan beta or higgsino-like scenarios in which decays of electroweak gauginos to tau leptons are dominant. The search uses a data set corresponding to an integrated luminosity of 77.2 fb(-1), which was recorded with the CMS detector during 2016 and 2017. No significant excess is observed with respect to the background prediction. Exclusion limits at 95% confidence level are presented in the top squark and lightest neutralino mass plane within the framework of simplified models, in which top squark masses up to 1100 GeV are excluded for a nearly massless neutralino.Peer reviewe

Measurement of the t(t)over-barb(b)over-bar production cross section in the all-jet final state in pp collisions at root s=13 TeV

A measurement of the production cross section of top quark pairs in association with two b jets (t (t) over barb (b) over bar) is presented using data collected in proton-proton collisions at root s=13 TeV by the CMS detector at the LHC corresponding to an integrated luminosity of 35.9 fb(-1). The cross section is measured in the all-jet decay channel of the top quark pair by selecting events containing at least eight jets, of which at least two are identified as originating from the hadronization of b quarks. A combination of multivariate analysis techniques is used to reduce the large background from multijet events not containing a top quark pair, and to help discriminate between jets originating from top quark decays and other additional jets. The cross section is determined for the total phase space to be 5.5 +/- 0.3 (stat)(-1.3)(+)(1.6) (syst)pb and also measured for two fiducial t (t) over barb (b) over bar, definitions. The measured cross sections are found to be larger than theoretical predictions by a factor of 1.5-2.4, corresponding to 1-2 standard deviations. (C) 2020 The Author. Published by Elsevier B.V.Peer reviewe

Search for supersymmetry in proton-proton collisions at 13 TeV in final states with jets and missing transverse momentum

Results are reported from a search for supersymmetric particles in the final state with multiple jets and large missing transverse momentum. The search uses a sample of proton-proton collisions at root s = 13 TeV collected with the CMS detector in 2016-2018, corresponding to an integrated luminosity of 137 fb(-1), representing essentially the full LHC Run 2 data sample. The analysis is performed in a four-dimensional search region defined in terms of the number of jets, the number of tagged bottom quark jets, the scalar sum of jet transverse momenta, and the magnitude of the vector sum of jet transverse momenta. No significant excess in the event yield is observed relative to the expected background contributions from standard model processes. Limits on the pair production of gluinos and squarks are obtained in the framework of simplified models for supersymmetric particle production and decay processes. Assuming the lightest supersymmetric particle to be a neutralino, lower limits on the gluino mass as large as 2000 to 2310 GeV are obtained at 95% confidence level, while lower limits on the squark mass as large as 1190 to 1630 GeV are obtained, depending on the production scenario.Peer reviewe

Search for electroweak production of a vector-like T quark using fully hadronic final states

A search is performed for electroweak production of a vector-like top quark partner T of charge 2/3 in association with a top or bottom quark, using proton-proton collision data at s = 13 TeV collected by the CMS experiment at the LHC in 2016. The data sample corresponds to an integrated luminosity of 35.9 fb−1. The search targets T quarks over a wide range of masses and fractional widths, decaying to a top quark and either a Higgs boson or a Z boson in fully hadronic final states. The search is performed using two experimentally distinct signatures that depend on whether or not each quark from the decays of the top quark, Higgs boson, or Z boson produces an individual resolved jet. Jet substructure, b tagging, and kinematic variables are used to identify the top quark and boson jets, and also to suppress the standard model backgrounds. The data are found to be consistent with the expected backgrounds. Upper limits at 95% confidence level are set on the cross sections for T quark-mediated production of tHQq, tZQq, and their sum, where Q is the associated top or bottom heavy quark and q is another associated quark. The limits are given for each search signature for various T quark widths up to 30% of the T quark mass, and are between 2 pb and 20 fb for T quark masses in the range 0.6–2.6 TeV. These results are significantly more sensitive than prior searches for electroweak single production of T → tH and represent the first constraints on T → tZ using hadronic decays of the Z boson with this production mode. [Figure not available: see fulltext.

Des déformations d'un pneumatique à un indicateur à l'échelle de la parcelle

National audienceLa circulation des engins agricoles sur les parcelles peut entrainer une diminution de la porosité du sol plus ou moins sévère et la formation d'ornières en surface. Des dispositifs de caractérisation sont indispensables pour répondre aux besoins d'identification et de délimitation des zones compactées, mais aussi aux besoins de traçabilité des contraintes appliquées au sol afin de suivre l'évolution de la structure du sol sous le passage des roues tout au long des cycles culturaux. De nombreux modèles de compactage ont été développés. Ils requièrent des paramètres d'entrée décrivant les caractéristiques de l'engin, celles des pneumatiques et celles du sol. La principale limite de ces modèles est la non prise en compte des variations spatiales de certains de ces paramètres, notamment la charge et le couple à la roue en dynamique. Nous avons développé un dispositif, appelé pneu-capteur car basé sur un pneumatique, qui fournit les variations spatiales des paramètres d'intérêt grâce à des modèles empiriques permettant de les estimer à partir des mesures de déformations des pneumatiques qui équipent le véhicule réalisant l'intervention culturale. Une fois estimés, ces paramètres servent à calculer un indicateur de compaction à l'échelle de la parcelle, permettant ainsi de réaliser le suivi objectif des dégradations, ou des améliorations, de la qualité physique du sol

Dispositif de prélèvement et de conditionnement automatiques d'échantillons référencés au cours d'une récolte

L'invention concerne un dispositif automatique de prélèvement, de conditionnement et de référencement d'échantillons au cours d'une récolte, destiné à être embarqué sur une machine de récolte du type comportant un dispositif transporteur du produit récolté. L'invention consiste en ce qu'il comprend des moyens de prélèvement de portions de récolte calibrées depuis l'un des éléments du dispositif transporteur, des moyens de conditionnement de chaque portion prélevée dans un contenant de manière à former un chapelet d'échantillons sensiblement identiques et des moyens de référencement de chaque échantillon formé. Application aux analyses de récolte

Effets sur la dénitrification et la production de gaz à effets de serre de la restauration de l’écoulement d’un ru dans une tourbière.

International audienc

Les zones humides comme aménagement tampon pour la rétention des contaminants : exemples d'une ancienne cressonnière, d'une tourbière et d'un bassin de stockage d'eau pour l'irrigation

PIREN-Seine. Phase V – Rapport de synthèse 2007-201

Les zones humides comme aménagement tampon pour la rétention des contaminants : exemples d'une ancienne cressonnière, d'une tourbière et d'un bassin de stockage d'eau pour l'irrigation

PIREN-Seine. Phase V – Rapport de synthèse 2007-201