Measurement and interpretation of same-sign W boson pair production in association with two jets in pp collisions at s = 13 TeV with the ATLAS detector

This paper presents the measurement of fducial and diferential cross sections for both the inclusive and electroweak production of a same-sign W-boson pair in association with two jets (W±W±jj) using 139 fb−1 of proton-proton collision data recorded at a centre-of-mass energy of √s = 13 TeV by the ATLAS detector at the Large Hadron Collider. The analysis is performed by selecting two same-charge leptons, electron or muon, and at least two jets with large invariant mass and a large rapidity diference. The measured fducial cross sections for electroweak and inclusive W±W±jj production are 2.92 ± 0.22 (stat.) ± 0.19 (syst.)fb and 3.38±0.22 (stat.)±0.19 (syst.)fb, respectively, in agreement with Standard Model predictions. The measurements are used to constrain anomalous quartic gauge couplings by extracting 95% confdence level intervals on dimension-8 operators. A search for doubly charged Higgs bosons H±± that are produced in vector-boson fusion processes and decay into a same-sign W boson pair is performed. The largest deviation from the Standard Model occurs for an H±± mass near 450 GeV, with a global signifcance of 2.5 standard deviations

Combination of searches for heavy spin-1 resonances using 139 fb−1 of proton-proton collision data at s = 13 TeV with the ATLAS detector

A combination of searches for new heavy spin-1 resonances decaying into different pairings of W, Z, or Higgs bosons, as well as directly into leptons or quarks, is presented. The data sample used corresponds to 139 fb−1 of proton-proton collisions at = 13 TeV collected during 2015–2018 with the ATLAS detector at the CERN Large Hadron Collider. Analyses selecting quark pairs (qq, bb, , and tb) or third-generation leptons (τν and ττ) are included in this kind of combination for the first time. A simplified model predicting a spin-1 heavy vector-boson triplet is used. Cross-section limits are set at the 95% confidence level and are compared with predictions for the benchmark model. These limits are also expressed in terms of constraints on couplings of the heavy vector-boson triplet to quarks, leptons, and the Higgs boson. The complementarity of the various analyses increases the sensitivity to new physics, and the resulting constraints are stronger than those from any individual analysis considered. The data exclude a heavy vector-boson triplet with mass below 5.8 TeV in a weakly coupled scenario, below 4.4 TeV in a strongly coupled scenario, and up to 1.5 TeV in the case of production via vector-boson fusion

Search for dark photons in rare Z boson decays with the ATLAS detector

A search for events with a dark photon produced in association with a dark Higgs boson via rare decays of the standard model Z boson is presented, using 139     fb − 1 of √ s = 13     TeV proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider. The dark boson decays into a pair of dark photons, and at least two of the three dark photons must each decay into a pair of electrons or muons, resulting in at least two same-flavor opposite-charge lepton pairs in the final state. The data are found to be consistent with the background prediction, and upper limits are set on the dark photon’s coupling to the dark Higgs boson times the kinetic mixing between the standard model photon and the dark photon, α D ϵ 2 , in the dark photon mass range of [5, 40] GeV except for the Υ mass window [8.8, 11.1] GeV. This search explores new parameter space not previously excluded by other experiments

Combined measurement of the Higgs boson mass from the H → γγ and H → ZZ∗ → 4ℓ decay channels with the ATLAS detector using √s = 7, 8, and 13 TeV pp collision data

A measurement of the mass of the Higgs boson combining the H → Z Z ∗ → 4 ℓ and H → γ γ decay channels is presented. The result is based on 140     fb − 1 of proton-proton collision data collected by the ATLAS detector during LHC run 2 at a center-of-mass energy of 13 TeV combined with the run 1 ATLAS mass measurement, performed at center-of-mass energies of 7 and 8 TeV, yielding a Higgs boson mass of 125.11 ± 0.09 ( stat ) ± 0.06 ( syst ) = 125.11 ± 0.11     GeV . This corresponds to a 0.09% precision achieved on this fundamental parameter of the Standard Model of particle physics

Color-center waveguides in low-energy electron-bombarded lithium fluoride

We employ a differential version of m-line spectroscopy through grating coupling in order to measure the refractive index of low-energy electron irradiated lithium fluoride crystal channel waveguides for broadband emission. Using photoresist films and a holographic setup for grating fabrication, we perform an accurate characterization of bidimensional structures and a direct quantitative comparison between treated and blank materials

Impurity and stress distribution in diamond films investigated by laser excited Raman and luminescence spectroscopy.

Impuritiy and stress distribution in diamond films have been studied by microRaman and microphotoluminescence. Raman and PL lateral profiles reveal the existence of a large anysotropic stress at the grain boundary resulting in frequency splitting and linewidth variations of the TO phonon. The detection of an additional peak at 1326 cm(-1) related to exagonal diamond phases and the high intensity reached by the 1.68 eV PL band at the coalescence region between two grains give evidence of preferential incorporation of defects at the grain boundary regions. Similarly, Raman and PL depth profiles indicate that the non-diamond intergrain tissue, abundant close to the substrate, induces compressive stress and represents a preferential site for Si diffusion

Diamond photoluminescence spectra: dependence on excitation energy and microstructure

Photoluminescence data are presented for diamond films grown by different techniques (hot-filament CVD, microwave PECVD, DC arc-jet) and excited in the range 450-650nm by different laser sources. In large-grain textured samples, sharp vibronic structures, related to nitrogen and silicon impurity centers, are clearly observed, whereas in small-grain, randomly oriented films spectra are dominated by broad luminescence bands, whose maxima move with excitation energy. In the former case a careful deconvolution of emission spectra allows us to obtain vibronic parameters of the centers and their fine structure details, while excitation spectra give the energy location of higher electronic excited states. On the other hand, the line-shape and the excitation-dependent shift of broad luminescence bands are related to a continuous distribution of gap states, able to trap photogenerated electron-hole pairs. (C) 1998 Elsevier Science S.A

Emission and excitation spectra of silicon-related luminescent centers in CVD-grown diamond films

Luminescence properties of silicon-related centers in CVD-grown diamond films and their spatial distribution along the growth direction have been investigated. It is found that the lineshape and peak position of the emission band depend both on excitation energy and light focalization depth, suggesting the coexistence of two optical centers related to isolated vacancies and to silicon-vacancy complexes. A simple model of the electronic structure of this defect is proposed. (C) 1997 Elsevier Science S.A

Structural and optical properties of low energy electrons irradiated KCl:LiF multilayer films

The optical behaviour of point defects created by low energy electron beams is studied in multilayer KCI:LiF films, grown by thermal evaporation onto amorphous substrates at constant temperatures ranging from 30 to 350 degrees C. The surface morphology of the samples was observed by the atomic force microscopy (AFM) technique, Large concentration of F and F-aggregate centres has been produced by 3-7 keV electron irradiation both in KCI and LiF layers which constitute the film. By pumping our films with appropriate Ar+ laser lines, we measured, for the first time, the luminescence in the near infrared region due to F-2 and F-3 centres in KCl and the typical emission of F-2 and F-3(+) centres in LiF in the visible region

Visible and infrared photoluminescence of low-energy electron irradiated LiF:KCl thin films

In this work we report the visible and infrared emissions of the color centers created in bilayer LiF:KCl thin films, obtained by pumping them with appropriate Ar+ and Ti:Sapphire laser lines, The large concentration of color centers induced by low-energy electron irradiation in a thin dielectric layer of controlled depth allows to investigate the spectroscopic properties of point defects which cannot be found in mixed crystals