Showing papers by "Cesare Bini 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: 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 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 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
50 citations
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
40 citations
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 ...
38 citations
TL;DR: In this paper, a measurement of the fragmentation functions of jets into charged particles in $p$+Pb collisions and $pp$ collisions is presented, using 28 nb$^{-1}$ and 26 pb$€-1$ of $pp€ data, both at $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV, collected in 2013 and 2015 with the ATLAS detector at the LHC.
29 citations