Search for heavy Majorana or Dirac neutrinos and right-handed W gauge bosons in final states with charged leptons and jets in pp collisions at √s = 13 TeV with the ATLAS detector

A search for heavy right-handed Majorana or Dirac neutrinos NR and heavy right-handed gauge bosons WR is performed in events with energetic electrons or muons, with the same or opposite electric charge, and energetic jets. The search is carried out separately for topologies of clearly separated final-state products (“resolved” channel) and topologies with boosted final states with hadronic and/or leptonic products partially overlapping and reconstructed as a large-radius jet (“boosted” channel). The events are selected from pp collision data at the LHC with an integrated luminosity of 139 fb−1 collected by the ATLAS detector at √s = 13 TeV. No significant deviations from the Standard Model predictions are observed. The results are interpreted within the theoretical framework of a left-right symmetric model, and lower limits are set on masses in the heavy righthanded WR boson and NR plane. The excluded region extends to about m(WR) = 6.4 TeV for both Majorana and Dirac NR neutrinos at m(NR) < 1 TeV. NR with masses of less than 3.5 (3.6) TeV are excluded in the electron (muon) channel at m(WR) = 4.8 TeV for the Majorana neutrinos, and limits of m(NR) up to 3.6 TeV for m(WR) = 5.2 (5.0) TeV in the electron (muon) channel are set for the Dirac neutrinos. These constitute the most stringent exclusion limits to date for the model considered

Software performance of the ATLAS track reconstruction for LHC run 3

Charged particle reconstruction in the presence of many simultaneous proton–proton (pp) collisions in the LHC is a challenging task for the ATLAS experiment’s reconstruction software due to the combinatorial complexity. This paper describes the major changes made to adapt the software to reconstruct high-activity collisions with an average of 50 or more simultaneous pp interactions per bunch crossing (pileup) promptly using the available computing resources. The performance of the key components of the track reconstruction chain and its dependence on pile-up are evaluated, and the improvement achieved compared to the previous software version is quantified. For events with an average of 60 pp collisions per bunch crossing, the updated track reconstruction is twice as fast as the previous version, without significant reduction in reconstruction efficiency and while reducing the rate of combinatorial fake tracks by more than a factor two

Observation of four-top-quark production in the multilepton final state with the ATLAS detector

This paper presents the observation of four-top-quark (tt¯tt¯) production in proton-proton collisions at the LHC. The analysis is performed using an integrated luminosity of 140 fb−1 at a centre-of-mass energy of 13 TeV collected using the ATLAS detector. Events containing two leptons with the same electric charge or at least three leptons (electrons or muons) are selected. Event kinematics are used to separate signal from background through a multivariate discriminant, and dedicated control regions are used to constrain the dominant backgrounds. The observed (expected) significance of the measured tt¯tt¯ signal with respect to the standard model (SM) background-only hypothesis is 6.1 (4.3) standard deviations. The tt¯tt¯ production cross section is measured to be 22.5+6.6−5.5 fb, consistent with the SM prediction of 12.0±2.4 fb within 1.8 standard deviations. Data are also used to set limits on the three-top-quark production cross section, being an irreducible background not measured previously, and to constrain the top-Higgs Yukawa coupling and effective field theory operator coefficients that affect tt¯tt¯ production

Klokkenluiders

ARIKELEN: 1. M.A.P. Bovens - Naar een Algemene Klokkenluiderswet 2. C. Raat - Een toevluchtsoord voor klokkenluiders: Brengt het Huis het ideaal van transparantie dichterbij? 3. J. Beckers, H.G. van de Bunt en K. van Wingerde - Het is transparantie wat de klok slaat: Publeaks als geduchte concurrent voor het Huis voor klokkenluiders? 4. H.G. de Jong en L.S. Mol - Het Adviespunt Klokkenluiders in de praktijk 5. G. de Graaf en K. Lasthuizen - Een luisteren oor: het interne meldsysteem integriteit binnen de Nederlandse overheid 6. K. Loyens - Over motieven voor het melden van misstanden; een kwalitatief onderzoek binnen het Belgische federale politiekorps 7. P. Stephenson en M. Levi - Principes van klokkenluiden: de benadering van de Raad van Europa 8. A.J. Brown - De bescherming van klokkenluiders: recente lessen uit Australië 9. Boekrecensie: Een bevlogen portret van Bradley Manning - B. de Graaf over 'The passion of Bradley Manning; the story behind the WikiLeaks whistleblowers' van Chase Madar. 10. Internetsites. SAMENVATTING: Dit themanummer beoogt een bijdrage te leveren aan de voortgaande discussie over de rol van klokkenluiders in de samenleving en de wijze waarop hun bescherming zou moeten worden geboden

Plot size and experimental unit relationship in exploratory experiments Relação do tamanho ótimo de parcela com o tamanho da unidade básica nos ensaios em brancos

Quality of field experiments data dependent upon adequate experimental design. This study investigated the relationship between the size of the basic unit for exploratory experiments and the optimum plot size, and the experiment precision with potato crop. Tuber yield of 24 rows, 144 mounds, were used to arrange experimental units of one, two, three, four, six, eight and 12 mounds. Tuber yield data of different mounds were used to arrange plot sizes with different numbers of basic units. The model CV(x)=A/X B was adjusted, in which CV(x) was the coefficient of variation among plots with different numbers of basic units. Optimum plot size was estimated with the modified maximum curvature method of the function CV(x)=A/X B, allowing completely random design. Experimental precision was estimated though the Hatheway method for different experimental arrangements. Based upon the modification of the maximum curvature method, for a fixed total experimental area, experimental unit size of potato initial experiments affects optimum plot size estimations with the same experimental precision and variable number of treatments.<br>A qualificação dos dados de experimentos de campo é obtida, em grande parte, pela escolha adequada do delineamento experimental. Este estudo foi realizado com o objetivo de investigar a relação do tamanho da unidade básica de ensaios em branco com o tamanho de parcela e com a precisão de experimentos com a cultura de batata. Os dados da produção de tubérculos de batata, obtidos de 24 linhas com 144 covas, foram usados para planejar unidades básicas (UB) de 1, 2, 3, 4, 6, 8 e 12 covas. Com os valores da produção das UB de diferentes tamanhos foram planejadas parcelas de diferentes números de UB. Foi ajustado o modelo CV(x)=A/X B, em que CV(x) é o coeficiente de variação entre as parcelas com X UB de tamanho. A estimativa do tamanho ótimo de parcela foi procedida pelo método da máxima curvatura modificada da função CV(x)=A/X B, considerando o delineamento inteiramente ao acaso, e a precisão foi estimada pelo método de Hatheway para diferentes configurações do delineamento experimental. Concluiu-se que o tamanho da unidade básica, usada nos ensaios em branco com batata, afeta a estimativa do tamanho ótimo de parcela pelo método da máxima curvatura modificada, sem alterar a precisão experimental, independente do número de tratamentos, mantendo fixa a área total do experimento