Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV

Search for direct stau production in events with two hadronic tau-leptons in root s=13 TeV pp collisions with the ATLAS detector

A search for the direct production of the supersymmetric partners ofτ-leptons (staus) in final stateswith two hadronically decayingτ-leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of139fb−1, recorded with the ATLAS detector at the LargeHadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected StandardModel background is observed. Limits are derived in scenarios of direct production of stau pairs with eachstau decaying into the stable lightest neutralino and oneτ-lepton in simplified models where the two staumass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidencelevel for a massless lightest neutralino

Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

New results from TopFitter

We present updated results for a global fit of dimension-six operators in the top quark sector of the Standard Model Effective Field Theory using experimental data from the Tevatron and the LHC at 7, 8 and 13 TeV center-of-mass energy. We include all contributions from dimension-six operators up to and including ?-4 in the effective field theory expansion. Furthermore we take the top quark decay into account and include in the fit experimental measurements which provide results for observables that depend on the kinematics of the top (anti)quark decay products. This opens up the possibility to study additional operators such as four-fermion operators which couple top quarks directly to leptons. A new strategy for sampling the parameter space of Wilson coefficients and treatment of systematic uncertainties is employed. In this contribution we restrict ourselves to present results in terms of bounds on individual operators

Reorganisation of Wnt-response pathways in colorectal tumorigenesis

In most colorectal tumours, APC mutation stabilises β-catenin and mimics elements of Wnt growth factor signalling, but the high frequency of epigenetic loss of Wnt antagonists indicates an additional role for ligand-mediated Wnt signalling. Here, we have investigated the expression of key components of β-catenin-independent Wnt response pathways to determine whether their profiles change during the transition from normal mucosa to colorectal adenomas. Transcription of the Wnt/planar cell polarity pathway determinant NKD1 (naked cuticle homologue 1) was induced in adenomas by a median 135-fold and in cancers by 7.4-fold. While some Frizzleds (FZDs) were downregulated in adenomas, the Wnt/Ca2+ receptors FZD3 and FZD6 were induced by a median factor of 6.5 and 4.6, respectively. Naked cuticle homologue 1, FZD3 and FZD6 expression were coordinated in pre-malignant disease, but this relationship was lost in invasive cancers, where FZD induction was seen less frequently. Naked cuticle homologue 1 expression was associated with nuclear localisation of phospho-c-Jun in adenomas. In cultured cells, NKD1 transcription was induced by lithium chloride but FZD3 expression required Wnt growth factor treatment. These data show that Wnt responses are consistently directed towards both β-catenin-independent routes in early colorectal tumorigenesis and elements of this are retained in more advanced cancers. These β-catenin-independent Wnt signalling pathways may provide novel targets for chemoprevention of early colorectal tumours

Pharmacogenetics Meets Metabolomics: Discovery of Tryptophan as a New Endogenous OCT2 Substrate Related to Metformin Disposition

Genetic polymorphisms of the organic cation transporter 2 (OCT2), encoded by SLC22A2, have been investigated in association with metformin disposition. A functional decrease in transport function has been shown to be associated with the OCT2 variants. Using metabolomics, our study aims at a comprehensive monitoring of primary metabolite changes in order to understand biochemical alteration associated with OCT2 polymorphisms and discovery of potential endogenous metabolites related to the genetic variation of OCT2. Using GC-TOF MS based metabolite profiling, clear clustering of samples was observed in Partial Least Square Discriminant Analysis, showing that metabolic profiles were linked to the genetic variants of OCT2. Tryptophan and uridine presented the most significant alteration in SLC22A2-808TT homozygous and the SLC22A2-808G>T heterozygous variants relative to the reference. Particularly tryptophan showed gene-dose effects of transporter activity according to OCT2 genotypes and the greatest linear association with the pharmacokinetic parameters (Clrenal, Clsec, Cl/F/kg, and Vd/F/kg) of metformin. An inhibition assay demonstrated the inhibitory effect of tryptophan on the uptake of 1-methyl-4-phenyl pyrinidium in a concentration dependent manner and subsequent uptake experiment revealed differential tryptophan-uptake rate in the oocytes expressing OCT2 reference and variant (808G>T). Our results collectively indicate tryptophan can serve as one of the endogenous substrate for the OCT2 as well as a biomarker candidate indicating the variability of the transport activity of OCT2

Fiducial and differential cross-section measurements of electroweak Wγjj production in pp collisions at s=13 TeV with the ATLAS detector

The observation of the electroweak production of a W boson and a photon in association with two jets, using pp collision data at the Large Hadron Collider at a centre of mass energy of s=13 TeV, is reported. The data were recorded by the ATLAS experiment from 2015 to 2018 and correspond to an integrated luminosity of 140 fb-1. This process is sensitive to the quartic gauge boson couplings via the vector boson scattering mechanism and provides a stringent test of the electroweak sector of the Standard Model. Events are selected if they contain one electron or muon, missing transverse momentum, at least one photon, and two jets. Multivariate techniques are used to distinguish the electroweak Wγjj process from irreducible background processes. The observed significance of the electroweak Wγjj process is well above six standard deviations, compared to an expected significance of 6.3 standard deviations. Fiducial and differential cross sections are measured in a fiducial phase space close to the detector acceptance, which are in reasonable agreement with leading order Standard Model predictions from MadGraph5+Pythia8 and Sherpa. The results are used to constrain new physics effects in the context of an effective field theory

Observation of quantum entanglement with top quarks at the ATLAS detector

Entanglement is a key feature of quantum mechanics1–3, with applications in fields such as metrology, cryptography, quantum information and quantum computation4–8. It has been observed in a wide variety of systems and length scales, ranging from the microscopic9–13 to the macroscopic14–16. However, entanglement remains largely unexplored at the highest accessible energy scales. Here we report the highest-energy observation of entanglement, in top–antitop quark events produced at the Large Hadron Collider, using a proton–proton collision dataset with a centre-of-mass energy of √s = 13 TeV and an integrated luminosity of 140 inverse femtobarns (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, at which 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 the 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 = −0.537 ± 0.002 (stat.) ± 0.019 (syst.) for 340GeV<380GeV. The observed result is more than five standard deviations from a scenario without entanglement and hence constitutes the first observation of entanglement in a pair of quarks and the highest-energy observation of entanglement so far

Search for light neutral particles decaying promptly into collimated pairs of electrons or muons in pp collisions at s = 13 TeV with the ATLAS detector

A search for a dark photon, a new light neutral particle, which decays promptly into collimated pairs of electrons or muons is presented. The search targets dark photons resulting from the exotic decay of the Standard Model Higgs boson, assuming its production via the dominant gluon-gluon fusion mode. The analysis is based on 140fb-1 of data collected with the ATLAS detector at the Large Hadron Collider from proton-proton collisions at a center-of-mass energy of 13 TeV. Events with collimated pairs of electrons or muons are analysed and background contributions are estimated using data-driven techniques. No significant excess in the data above the Standard Model background is observed. Upper limits are set at 95% confidence level on the branching ratio of the Higgs boson decay into dark photons between 0.001% and 5%, depending on the assumed dark photon mass and signal model

Performance of electron and photon triggers in ATLAS during LHC Run 2

Electron and photon triggers covering transverseenergies from 5 GeV to several TeV are essential for theATLAS experiment to record signals for a wide variety ofphysics: from Standard Model processes to searches for newphenomena in both proton–proton and heavy-ion collisions.To cope with a fourfold increase of peak LHC luminosityfrom 2015 to 2018 (Run 2), to 2.1×1034cm−2s−1, anda similar increase in the number of interactions per beam-crossing to about 60, trigger algorithms and selections wereoptimised to control the rates while retaining a high effi-ciency for physics analyses. For proton–proton collisions, thesingle-electron trigger efficiency relative to a single-electronoffline selection is at least 75% for an offline electron of31 GeV, and rises to 96% at 60 GeV; the trigger efficiency ofa 25 GeV leg of the primary diphoton trigger relative to a tightoffline photon selection is more than 96% for an offline pho-ton of 30 GeV. For heavy-ion collisions, the primary electronand photon trigger efficiencies relative to the correspondingstandard offline selections are at least 84% and 95%, respec-tively, at 5 GeV above the corresponding trigger threshold