Showing papers by "Andreas Korn published in 2018"
TL;DR: In this paper, a search for new phenomena in final states with an energetic jet and large missing transverse momentum is reported, and the results are translated into exclusion limits in models with pair-produced weakly interacting dark-matter candidates, large extra spatial dimensions, and supersymmetric particles in several compressed scenarios.
Abstract: Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses proton-proton collision data corresponding to an integrated luminosity of 36.1 fb−1 at a centre-of-mass energy of 13 TeV collected in 2015 and 2016 with the ATLAS detector at the Large Hadron Collider. Events are required to have at least one jet with a transverse momentum above 250 GeV and no leptons (e or μ). Several signal regions are considered with increasing requirements on the missing transverse momentum above 250 GeV. Good agreement is observed between the number of events in data and Standard Model predictions. The results are translated into exclusion limits in models with pair-produced weakly interacting dark-matter candidates, large extra spatial dimensions, and supersymmetric particles in several compressed scenarios.
358 citations
TL;DR: In this article, the observed significance is 5.8 standard deviations, compared to an expectation of 4.9 standard deviations and the observed (expected) significance is 6.3 (5.1) standard deviations.
306 citations
TL;DR: In this paper, the properties of the Higgs boson were measured in the two-photon final state using 36.1 fb-1 of proton? proton collision data recorded at ffiffi √s = 13 TeV by the ATLAS experiment at the Large Hadron Collider.
Abstract: Properties of the Higgs boson are measured in the two-photon final state using 36.1 fb-1 of proton? proton collision data recorded at ffiffi √s = 13 TeV by the ATLAS experiment at the Large Hadron Collider. Cross-section measurements for the production of a Higgs boson through gluon-gluon fusion, vectorboson fusion, and in association with a vector boson or a top-quark pair are reported. The signal strength, defined as the ratio of the observed to the expected signal yield, is measured for each of these production processes as well as inclusively. The global signal strength measurement of 0.99 ± 0.14 improves on the precision of the ATLAS measurement at √s = 7 and 8 TeV by a factor of two. Measurements of gluon-gluon fusion and vector-boson fusion productions yield signal strengths compatible with the Standard Model prediction. Measurements of simplified template cross sections, designed to quantify the different Higgs boson production processes in specific regions of phase space, are reported. The cross section for the production of the Higgs boson decaying to two isolated photons in a fiducial region closely matching the experimental selection of the photons is measured to be 55 ± 10 fb, which is in good agreement with the Standard Model prediction of 64 ± 2 fb. Furthermore, cross sections in fiducial regions enriched in Higgs boson production in vector-boson fusion or in association with large missing transverse momentum, leptons or top-quark pairs are reported. Differential and double-differential measurements are performed for several variables related to the diphoton kinematics as well as the kinematics and multiplicity of the jets produced in association with a Higgs boson. These differential cross sections are sensitive to higher order QCD corrections and properties of the Higgs boson, such as its spin and CP quantum numbers. No significant deviations from a wide array of Standard Model predictions are observed. Finally, the strength and tensor structure of the Higgs boson interactions are investigated using an effective Lagrangian, which introduces additional CP-even and CP-odd interactions. No significant new physics contributions are observed.
251 citations
TL;DR: A search for the decay of the Standard Model Higgs boson into a bb¯ pair when produced in association with a W or Z boson is performed with the ATLAS detector as mentioned in this paper.
221 citations
TL;DR: A search for the electroweak production of charginos, neutralinos and sleptons decaying into final states involving two or three electrons or muons is presented and stringent limits at 95% confidence level are placed on the masses of relevant supersymmetric particles.
Abstract: A search for the electroweak production of charginos, neutralinos and sleptons decaying into final states involving two or three electrons or muons is presented. The analysis is based on 36.1 fb$^{-1}$ of $\sqrt{s}=13$ TeV proton–proton collisions recorded by the ATLAS detector at the Large Hadron Collider. Several scenarios based on simplified models are considered. These include the associated production of the next-to-lightest neutralino and the lightest chargino, followed by their decays into final states with leptons and the lightest neutralino via either sleptons or Standard Model gauge bosons, direct production of chargino pairs, which in turn decay into leptons and the lightest neutralino via intermediate sleptons, and slepton pair production, where each slepton decays directly into the lightest neutralino and a lepton. No significant deviations from the Standard Model expectation are observed and stringent limits at 95% confidence level are placed on the masses of relevant supersymmetric particles in each of these scenarios. For a massless lightest neutralino, masses up to 580 GeV are excluded for the associated production of the next-to-lightest neutralino and the lightest chargino, assuming gauge-boson mediated decays, whereas for slepton-pair production masses up to 500 GeV are excluded assuming three generations of mass-degenerate sleptons.
181 citations
TL;DR: In this paper, the authors presented a search for direct electroweak gaugino or gluino pair production with a chargino nearly mass-degenerate with a stable neutralino.
Abstract: This paper presents a search for direct electroweak gaugino or gluino pair production with a chargino nearly mass-degenerate with a stable neutralino. It is based on an integrated luminosity of 36.1 fb$^{−1}$ of pp collisions at $ \sqrt{s}=13 $ TeV collected by the ATLAS experiment at the LHC. The final state of interest is a disappearing track accompanied by at least one jet with high transverse momentum from initial-state radiation or by four jets from the gluino decay chain. The use of short track segments reconstructed from the innermost tracking layers significantly improves the sensitivity to short chargino lifetimes. The results are found to be consistent with Standard Model predictions. Exclusion limits are set at 95% confidence level on the mass of charginos and gluinos for different chargino lifetimes. For a pure wino with a lifetime of about 0.2 ns, chargino masses up to 460 GeV are excluded. For the strong production channel, gluino masses up to 1.65 TeV are excluded assuming a chargino mass of 460 GeV and lifetime of 0.2 ns.
147 citations
TL;DR: In this article, a search for the standard model Higgs boson produced in association with a top-quark pair, t(t)overbarH, is presented using 36.1 fb(-1) of pp collision data at root s = 13 TeV collecte...
Abstract: A search for the standard model Higgs boson produced in association with a top-quark pair, t(t)overbarH, is presented. The analysis uses 36.1 fb(-1) of pp collision data at root s = 13 TeV collecte ...
108 citations
TL;DR: In this paper, an angular analysis of the decay B-d(0) -> K*mu(+)mu(-) is presented, based on proton-proton collision data recorded by the ATLAS experiment at the LHC.
Abstract: An angular analysis of the decay B-d(0) -> K*mu(+)mu(-) is presented, based on proton-proton collision data recorded by the ATLAS experiment at the LHC. The study is using 20.3 fb(-1) of integra ...
105 citations
TL;DR: A search for new heavy particles that decay into top-quark pairs is performed using data collected from proton–proton collisions at a centre-of-mass energy of 13 $$\text {TeV}$$TeV by the ATLAS detector at the Large Hadron Collider.
Abstract: A search for new heavy particles that decay into top-quark pairs is performed using data collected from proton-proton collisions at a centre-of-mass energy of 13 TeV by the ATLAS detector at the La ...
101 citations
TL;DR: In this article, a search for electroweak production of supersymmetric particles using recursive jigsaw reconstruction was performed in two-and three-lepton final states using a technique that assigns reconstructed objects to the most probable hemispheres of the decay trees.
Abstract: A search for electroweak production of supersymmetric particles is performed in two-lepton and three-lepton final states using recursive jigsaw reconstruction, a technique that assigns reconstructed objects to the most probable hemispheres of the decay trees, allowing one to construct tailored kinematic variables to separate the signal and background. The search uses data collected in 2015 and 2016 by the ATLAS experiment in s=13 TeV proton-proton collisions at the CERN Large Hadron Collider corresponding to an integrated luminosity of 36.1 fb-1. Chargino-neutralino pair production, with decays via W/Z bosons, is studied in final states involving leptons and jets and missing transverse momentum for scenarios with large and intermediate mass splittings between the parent particle and lightest supersymmetric particle, as well as for the scenario where this mass splitting is close to the mass of the Z boson. The latter case is challenging since the vector bosons are produced with kinematic properties that are similar to those in Standard Model processes. Results are found to be compatible with the Standard Model expectations in the signal regions targeting large and intermediate mass splittings, and chargino-neutralino masses up to 600 GeV are excluded at 95% confidence level for a massless lightest supersymmetric particle. Excesses of data above the expected background are found in the signal regions targeting low mass splittings, and the largest local excess amounts to 3.0 standard deviations. © 2018 CERN, for the ATLAS Collaboration. Published by the American Physical Society.
97 citations
TL;DR: In this article, the coupling properties of the Higgs boson were studied in the four-lepton (e, μ) decay channel using 36.1 fb−1 collision data from the LHC at a centre-of-mass energy of 13 TeV collected by the ATLAS detector.
Abstract: The coupling properties of the Higgs boson are studied in the four-lepton (e, μ) decay channel using 36.1 fb−1 of pp collision data from the LHC at a centre-of-mass energy of 13 TeV collected by the ATLAS detector. Cross sections are measured for the main production modes in several exclusive regions of the Higgs boson production phase space and are interpreted in terms of coupling modifiers. The inclusive cross section times branching ratio for H → ZZ∗ decay and for a Higgs boson absolute rapidity below 2.5 is measured to be 1. 73 − 0.23 + 0.24 (stat.) − 0.08 + 0.10 (exp.) ± 0.04(th.) pb compared to the Standard Model prediction of 1.34±0.09 pb. In addition, the tensor structure of the Higgs boson couplings is studied using an effective Lagrangian approach for the description of interactions beyond the Standard Model. Constraints are placed on the non-Standard-Model CP-even and CP-odd couplings to Z bosons and on the CP-odd coupling to gluons.
TL;DR: In this article, a search for pair production of up-type vector-like quarks with a significant branching ratio into a top quark and either a Standard Model Higgs boson or a Z boson is presented.
Abstract: A search for pair production of up-type vector-like quarks (T) with a significant branching ratio into a top quark and either a Standard Model Higgs boson or a Z boson is presented. The same analys ...
TL;DR: In this article, the results of a search for the direct pair production of top quarks, the supersymmetric partner of the top quark, in final states with one isolated electron or muon, several energetic jets, and missing transverse momentum are reported.
Abstract: The results of a search for the direct pair production of top squarks, the supersymmetric partner of the top quark, in final states with one isolated electron or muon, several energetic jets, and missing transverse momentum are reported. The analysis also targets spin-0 mediator models, where the mediator decays into a pair of dark-matter particles and is produced in association with a pair of top quarks. The search uses data from proton-proton collisions delivered by the Large Hadron Collider in 2015 and 2016 at a centre-of-mass energy of $ \sqrt{s}=13 $ TeV and recorded by the ATLAS detector, corresponding to an integrated luminosity of 36 fb$^{−1}$. A wide range of signal scenarios with different mass-splittings between the top squark, the lightest neutralino and possible intermediate supersymmetric particles are considered, including cases where the W bosons or the top quarks produced in the decay chain are off-shell. No significant excess over the Standard Model prediction is observed. The null results are used to set exclusion limits at 95% confidence level in several supersymmetry benchmark models. For pair-produced top-squarks decaying into top quarks, top-squark masses up to 940 GeV are excluded. Stringent exclusion limits are also derived for all other considered top-squark decay scenarios. For the spin-0 mediator models, upper limits are set on the visible cross-section.
TL;DR: In this article, the efficiency of detecting b-hadrons was measured using a high purity sample of dileptonic top quark-antiquark pairs selected from the 36.1 fb$^{−1}$ of data collected by the ATLAS detector in 2015 and 2016 from proton-proton collisions produced by the Large Hadron Collider at a centre-of-mass energy of 13 $ TeV.
Abstract: The efficiency to identify jets containing b-hadrons (b-jets) is measured using a high purity sample of dileptonic top quark-antiquark pairs ( $ t\overline{t} $ ) selected from the 36.1 fb$^{−1}$ of data collected by the ATLAS detector in 2015 and 2016 from proton-proton collisions produced by the Large Hadron Collider at a centre-of-mass energy $ \sqrt{s}=13 $ TeV. Two methods are used to extract the efficiency from $ t\overline{t} $ events, a combinatorial likelihood approach and a tag-and-probe method. A boosted decision tree, not using b-tagging information, is used to select events in which two b-jets are present, which reduces the dominant uncertainty in the modelling of the flavour of the jets. The efficiency is extracted for jets in a transverse momentum range from 20 to 300 GeV, with data-to-simulation scale factors calculated by comparing the efficiency measured using collision data to that predicted by the simulation. The two methods give compatible results, and achieve a similar level of precision, measuring data-to-simulation scale factors close to unity with uncertainties ranging from 2% to 12% depending on the jet transverse momentum.
TL;DR: In this paper, a search for charged Higgs bosons heavier than the top quark and decaying via H$ √ tb → tb is presented, where multivariate techniques are used to discriminate between signal and background events.
Abstract: A search for charged Higgs bosons heavier than the top quark and decaying via H$^{±}$ → tb is presented. The data analysed corresponds to 36.1 fb$^{−1}$ of pp collisions at $ \sqrt{s}=13 $ TeV and was recorded with the ATLAS detector at the LHC in 2015 and 2016. The production of a charged Higgs boson in association with a top quark and a bottom quark, pp → tbH$^{±}$, is explored in the mass range from m$_{H}$± = 200 to 2000 GeV using multi-jet final states with one or two electrons or muons. Events are categorised according to the multiplicity of jets and how likely these are to have originated from hadronisation of a bottom quark. Multivariate techniques are used to discriminate between signal and background events. No significant excess above the background-only hypothesis is observed and exclusion limits are derived for the production cross-section times branching ratio of a charged Higgs boson as a function of its mass, which range from 2.9 pb at m$_{H}$± = 200 GeV to 0.070 pb at m$_{H}$± = 2000 GeV. The results are interpreted in two benchmark scenarios of the Minimal Supersymmetric Standard Model.
TL;DR: The production of excited charmonium and bottomonium states is found to be suppressed relative to that of the ground states in central p+Pb collisions and quarkonium differential cross sections are measured.
Abstract: The modification of the production of J/psi, psi(2S), and gamma (nS) (n = 1, 2, 3) in p+Pb collisions with respect to their production in pp collisions has been studied. The p+Pb and pp datasets us ...
TL;DR: This Letter describes a new search for dijet resonances where this limitation is overcome by recording only the event information calculated by the jet trigger algorithms, thereby allowing much higher event rates with reduced storage needs.
Abstract: Searches for dijet resonances with sub-TeV masses using the ATLAS detector at the Large Hadron Collider can be statistically limited by the bandwidth available to inclusive single-jet triggers, who ...
TL;DR: In this article, a search for supersymmetry involving the pair production of gluinos decaying via third-generation squarks into the lightest neutralino ((chi) over tilde (0)(1)) is reported.
Abstract: A search for supersymmetry involving the pair production of gluinos decaying via third-generation squarks into the lightest neutralino ((chi) over tilde (0)(1)) is reported. It uses LHC proton-prot ...
TL;DR: In this article, a search for new resonances decaying into a WW or WZ boson pair was conducted, where one W boson decays leptonically and the other W or Z bosons decays hadronically.
Abstract: A search is conducted for new resonances decaying into a WW or WZ boson pair, where one W boson decays leptonically and the other W or Z boson decays hadronically. It is based on proton-proton coll ...
INAF1, University of Pisa2, Keele University3, Spanish National Research Council4, University of Florence5, University of Barcelona6, Leiden University7, Vilnius University8, University of Cambridge9, Lund University10, Uppsala University11, University of Catania12, Polish Academy of Sciences13, University of Valparaíso14, University of Padua15, Diego Portales University16, Andrés Bello National University17, European Southern Observatory18, University of Porto19
TL;DR: In this article, a homogeneous analysis of eight open clusters using the Gaia-DR1 TGAS catalogue for bright members and information from the Gaia -ESO Survey for fainter stars was performed.
Abstract: Context. Determination and calibration of the ages of stars, which heavily rely on stellar evolutionary models, are very challenging, while representing a crucial aspect in many astrophysical areas.Aims. We describe the methodologies that, taking advantage of Gaia -DR1 and the Gaia -ESO Survey data, enable the comparison of observed open star cluster sequences with stellar evolutionary models. The final, long-term goal is the exploitation of open clusters as age calibrators.Methods. We perform a homogeneous analysis of eight open clusters using the Gaia -DR1 TGAS catalogue for bright members and information from the Gaia -ESO Survey for fainter stars. Cluster membership probabilities for the Gaia -ESO Survey targets are derived based on several spectroscopic tracers. The Gaia -ESO Survey also provides the cluster chemical composition. We obtain cluster parallaxes using two methods. The first one relies on the astrometric selection of a sample of bona fide members, while the other one fits the parallax distribution of a larger sample of TGAS sources. Ages and reddening values are recovered through a Bayesian analysis using the 2MASS magnitudes and three sets of standard models. Lithium depletion boundary (LDB) ages are also determined using literature observations and the same models employed for the Bayesian analysis.Results. For all but one cluster, parallaxes derived by us agree with those presented in Gaia Collaboration (2017, AA we provide evidence supporting our own determination. Inferred cluster ages are robust against models and are generally consistent with literature values.Conclusions. The systematic parallax errors inherent in the Gaia DR1 data presently limit the precision of our results. Nevertheless, we have been able to place these eight clusters onto the same age scale for the first time, with good agreement between isochronal and LDB ages where there is overlap. Our approach appears promising and demonstrates the potential of combining Gaia and ground-based spectroscopic datasets.
TL;DR: Despite prompt and non-prompt J/\psi and J/ψ arising from different mechanisms, the dependence of their nuclear modification factors on centrality is found to be quite similar.
Abstract: A measurement of J/ψ and ψ(2S) production is presented. It is based on a data sample from Pb+Pb collisions at sNN−−−√=5.02 TeV and pp collisions at s√=5.02 TeV recorded by the ATLAS detector at the LHC in 2015, corresponding to an integrated luminosity of 0.42 nb−1 and 25 pb−1 in Pb+Pb and pp, respectively. The measurements of per-event yields, nuclear modification factors, and non-prompt fractions are performed in the dimuon decay channel for 9
TL;DR: A direct search for the standard model Higgs boson decaying to a pair of charm quarks is presented and the H→cc[over ¯] signature is identified using charm-tagging algorithms.
Abstract: A direct search for the standard model Higgs boson decaying to a pair of charm quarks is presented Associated production of the Higgs and Z bosons, in the decay mode ZH→l^{+}l^{-}cc[over ¯] is studied A data set with an integrated luminosity of 361 fb^{-1} of pp collisions at sqrt[s]=13TeV recorded by the ATLAS experiment at the LHC is used The H→cc[over ¯] signature is identified using charm-tagging algorithms The observed (expected) upper limit on σ(pp→ZH)×B(H→cc[over ¯]) is 27 (39_{-11}^{+21}) pb at the 95% confidence level for a Higgs boson mass of 125 GeV, while the standard model value is 26 fb
TL;DR: In this paper, a search for pair production of the supersymmetric partners of the Higgs boson (higgsinos H˜) in gauge-mediated scenarios is reported.
Abstract: A search for pair production of the supersymmetric partners of the Higgs boson (higgsinos H˜) in gauge-mediated scenarios is reported Each higgsino is assumed to decay to a Higgs boson and a gravitino Two complementary analyses, targeting high- and low-mass signals, are performed to maximize sensitivity The two analyses utilize LHC pp collision data at a center-of-mass energy s=13 TeV, the former with an integrated luminosity of 361 fb-1 and the latter with 243 fb-1, collected with the ATLAS detector in 2015 and 2016 The search is performed in events containing missing transverse momentum and several energetic jets, at least three of which must be identified as b-quark jets No significant excess is found above the predicted background Limits on the cross section are set as a function of the mass of the H˜ in simplified models assuming production via mass-degenerate higgsinos decaying to a Higgs boson and a gravitino Higgsinos with masses between 130 and 230 GeV and between 290 and 880 GeV are excluded at the 95% confidence level Interpretations of the limits in terms of the branching ratio of the higgsino to a Z boson or a Higgs boson are also presented, and a 45% branching ratio to a Higgs boson is excluded for mH˜≈400 GeV
TL;DR: In this article, a search is conducted for a beyond-the-standard-model boson using events where a Higgs boson with mass 125 GeV decays to four leptons (l = e or μ).
Abstract: A search is conducted for a beyond-the-Standard-Model boson using events where a Higgs boson with mass 125 GeV decays to four leptons (l = e or μ). This decay is presumed to occur via an intermediate state which contains one or two on-shell, promptly decaying bosons: H → ZX/XX → 4l, where X is a new vector boson Z$_{d}$ or pseudoscalar a with mass between 1 and 60 GeV. The search uses pp collision data collected with the ATLAS detector at the LHC with an integrated luminosity of 36.1 fb$^{−1}$ at a centre-of-mass energy $ \sqrt{s}=13 $ TeV. No significant excess of events above Standard Model background predictions is observed, therefore, upper limits at 95% confidence level are set on modelindependent fiducial cross-sections, and on the Higgs boson decay branching ratios to vector and pseudoscalar bosons in two benchmark models.
TL;DR: In this paper, a measurement of jet fragmentation functions in 0.49 nb−1 of Pb+Pb collisions at √sNN=5.02 TeV collected in 2015 with the ATLAS detector at the LHC is presented.
Abstract: This paper presents a measurement of jet fragmentation functions in 0.49 nb−1 of Pb+Pb collisions and 25 pb−1 of pp collisions at √sNN=5.02 TeV collected in 2015 with the ATLAS detector at the LHC. These measurements provide insight into the jet quenching process in the quark-gluon plasma created in the aftermath of ultrarelativistic collisions between two nuclei. The modifications to the jet fragmentation functions are quantified by dividing the measurements in Pb+Pb collisions by baseline measurements in pp collisions. This ratio is studied as a function of the transverse momentum of the jet, the jet rapidity, and the centrality of the collision. In both collision systems, the jet fragmentation functions are measured for jets with transverse momentum between 126 and 398 GeV and with an absolute value of jet rapidity less than 2.1. An enhancement of particles carrying a small fraction of the jet momentum is observed, which increases with centrality and with increasing jet transverse momentum. Yields of particles carrying a very large fraction of the jet momentum are also observed to be enhanced. Between these two enhancements of the fragmentation functions a suppression of particles carrying an intermediate fraction of the jet momentum is observed in Pb+Pb collisions. A small dependence of the modifications on jet rapidity is observed.
TL;DR: In this paper, a search for the narrow structure X(5568) reported by the D0 Collaboration in the decay sequence X→B_{s}−π−±, B_{s−π −1}→J/ψϕ, is presented based on a data sample recorded with the ATLAS detector at the LHC.
Abstract: A search for the narrow structure, X(5568), reported by the D0 Collaboration in the decay sequence X→B_{s}^{0}π^{±}, B_{s}^{0}→J/ψϕ, is presented The analysis is based on a data sample recorded with the ATLAS detector at the LHC corresponding to 49 fb^{-1} of pp collisions at 7 TeV and 195 fb^{-1} at 8 TeV No significant signal was found Upper limits on the number of signal events, with properties corresponding to those reported by D0, and on the X production rate relative to B_{s}^{0} mesons, ρ_{X}, were determined at 95% confidence level The results are N(X)<382 and ρ_{X}<0015 for B_{s}^{0} mesons with transverse momenta above 10 GeV, and N(X)<356 and ρ_{X}<0016 for transverse momenta above 15 GeV Limits are also set for potential B_{s}^{0}π^{±} resonances in the mass range 5550 to 5700 MeV
TL;DR: In this paper, a search for flavour-changing neutral current processes in top-quark decays is presented, with one top quark decaying through the t → qZ (q = u, c) flavourchanging neutral-current channel, and the other through the dominant Standard Model mode t → bW.
Abstract: A search for flavour-changing neutral-current processes in top-quark decays is presented. Data collected with the ATLAS detector from proton-proton collisions at the Large Hadron Collider at a centre-of-mass energy of $ \sqrt{s}=13 $ TeV, corresponding to an integrated luminosity of 36.1 fb$^{−1}$, are analysed. The search is performed using top-quark pair events, with one top quark decaying through the t → qZ (q = u, c) flavour-changing neutral-current channel, and the other through the dominant Standard Model mode t → bW. Only Z boson decays into charged leptons and leptonic W boson decays are considered as signal. Consequently, the final-state topology is characterized by the presence of three isolated charged leptons (electrons or muons), at least two jets, one of the jets originating from a b-quark, and missing transverse momentum from the undetected neutrino. The data are consistent with Standard Model background contributions, and at 95% confidence level the search sets observed (expected) upper limits of 1.7 × 10$^{−4}$ (2.4 × 10$^{−4}$) on the t → uZ branching ratio and 2.4 × 10$^{−4}$ (3.2 × 10$^{−4}$) on the t → cZ branching ratio, constituting the most stringent limits to date.
TL;DR: In this paper, a search for the direct pair production of the stop, the supersymmetric partner of the top quark, was presented for the R-parity-violating coupling to a final state with two leptons.
Abstract: A search is presented for the direct pair production of the stop, the supersymmetric partner of the top quark, that decays through an R-parity-violating coupling to a final state with two leptons a ...
TL;DR: In this article, a search for the pair production of heavy vector-like B quarks was presented, primarily targeting B quark decays into a W boson and a top quark.
Abstract: A search is presented for the pair production of heavy vector-like B quarks, primarily targeting B quark decays into a W boson and a top quark. The search is based on 36.1 fb(-1) of pp collisions a ...
TL;DR: In this article, the exclusive decays of the Higgs and Z bosons to a ϕ or ρ meson and a photon are performed with a pp collision data sample corresponding to an integrated luminosity of up to 35.6 fb$^{−1}$ collected at $ \sqrt{s}=13 $ TeV with the ATLAS detector at the CERN Large Hadron Collider.
Abstract: A search for the exclusive decays of the Higgs and Z bosons to a ϕ or ρ meson and a photon is performed with a pp collision data sample corresponding to an integrated luminosity of up to 35.6 fb$^{−1}$ collected at $ \sqrt{s}=13 $ TeV with the ATLAS detector at the CERN Large Hadron Collider. These decays have been suggested as a probe of the Higgs boson couplings to light quarks. No significant excess of events is observed above the background, as expected from the Standard Model. Upper limits at 95% confidence level were obtained on the branching fractions of the Higgs boson decays to ϕγ and ργ of 4.8 × 10$^{−4}$ and 8.8 × 10$^{−4}$, respectively. The corresponding 95% confidence level upper limits for the Z boson decays are 0.9 × 10$^{−6}$ and 25 × 10$^{−6}$ for ϕγ and ργ, respectively.