Search for pair-produced scalar and vector leptoquarks decaying into third-generation quarks and first- or second-generation leptons in pp collisions with the ATLAS detector

A search for pair-produced scalar and vector leptoquarks decaying into quarks and leptons of different generations is presented. It uses the full LHC Run 2 (2015–2018) data set of 139 fb−1 collected with the ATLAS detector in proton–proton collisions at a centre-of-mass energy of √ s = 13 TeV. Scalar leptoquarks with charge −(1/3)e as well as scalar and vector leptoquarks with charge +(2/3)e are considered. All possible decays of the pair-produced leptoquarks into quarks of the third generation (t, b) and charged or neutral leptons of the first or second generation (e, µ, ν) with exactly one electron or muon in the final state are investigated. No significant deviations from the Standard Model expectation are observed. Upper limits on the production cross-section are provided for eight models as a function of the leptoquark mass and the branching ratio of the leptoquark into the charged or neutral lepton. In addition, lower limits on the leptoquark masses are derived for all models across a range of branching ratios. Two of these models have the goal of providing an explanation for the recent B-anomalies. In both models, a vector leptoquark decays into charged and neutral leptons of the second generation with a similar branching fraction. Lower limits of 1980 GeV and 1710 GeV are set on the leptoquark mass for these two models

Evidence of pair production of longitudinally polarised vector bosons and study of CP properties in ZZ - 4ℓ events with the ATLAS detector at √s = 13 TeV

A study of the polarisation and CP properties in ZZ production is presented. The used data set corresponds to an integrated luminosity of 140 fb−1 of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector at the Large Hadron Collider. The ZZ candidate events are reconstructed using two same-favour opposite-charge electron or muon pairs. The production of two longitudinally polarised Z bosons is measured with a signifcance of 4.3 standard deviations, and its cross-section is measured in a fducial phase space to be 2.45 ± 0.60 fb, consistent with the next-to-leadingorder Standard Model prediction. The inclusive diferential cross-section as a function of a CP-sensitive angular observable is also measured. The results are used to constrain anomalous CP-odd neutral triple gauge couplings

Measurements of the suppression and correlations of dijets in Xe+Xe collisions at √ sNN = 5.44 TeV

Measurements of the suppression and correlations of dijets is performed using 3 µb−1 of Xe+Xe data at √sNN = 5.44 TeV collected with the ATLAS detector at the CERN Large Hadron Collider. Dijets with jets reconstructed using the R = 0.4 anti-kt algorithm are measured differentially in jet pT over the range of 32 to 398 GeV and the centrality of the collisions. Significant dijet momentum imbalance is found in the most central Xe+Xe collisions, which decreases in more peripheral collisions. Results from the measurement of per-pair normalized and absolutely normalized dijet pT balance are compared with previous Pb+Pb measurements at √sNN = 5.02 TeV. The differences between the dijet suppression in Xe+Xe and Pb+Pb are further quantified by the ratio of pair nuclear-modification factors. The results are found to be consistent with those measured in Pb+Pb data when compared in classes of the same event activity and when taking into account the difference between the center-of-mass energies of the initial parton scattering process in Xe+Xe and Pb+Pb collisions. These results should provide input for a better understanding of the role of energy density, system size, path length, and fluctuations in the parton energy loss

Search for high-mass Wγ and Zγ resonances using hadronic W/Z boson decays from 139 fb−1 of pp collisions at s√ = 13 TeV with the ATLAS detector

A search for high-mass charged and neutral bosons decaying to Wγ and Zγ final states is presented in this paper. The analysis uses a data sample of s√ = 13 TeV proton-proton collisions with an integrated luminosity of 139 fb−1 collected by the ATLAS detector during LHC Run 2 operation. The sensitivity of the search is determined using models of the production and decay of spin-1 charged bosons and spin-0/2 neutral bosons. The range of resonance masses explored extends from 1.0 TeV to 6.8 TeV. At these high resonance masses, it is beneficial to target the hadronic decays of the W and Z bosons because of their large branching fractions. The decay products of the high-momentum W/Z bosons are strongly collimated and boosted-boson tagging techniques are employed to improve the sensitivity. No evidence of a signal above the Standard Model backgrounds is observed, and upper limits on the production cross-sections of these bosons times their branching fractions to Wγ and Zγ are derived for various boson production models

Search for direct production of electroweakinos in fnal states with one lepton, jets and missing transverse momentum in pp collisions at √s = 13 TeV with the ATLAS detector

Searches for electroweak production of wino-like chargino pairs, χ˜ + 1 χ˜ − 1 , and of wino-like chargino and next-to-lightest neutralino, χ˜ ± 1 χ˜ 0 2 , are presented. The models explored assume that the charginos decay into a W boson and the lightest neutralino, χ˜ ± 1 → W±χ˜ 0 1 . The next-to-lightest neutralinos are degenerate in mass with the chargino and decay to χ˜ 0 1 and either a Z or a Higgs boson, χ˜ 0 2 → Zχ˜ 0 1 or hχ˜ 0 1 . The searches exploit the presence of a single isolated lepton and missing transverse momentum from the W boson decay products and the lightest neutralinos, and the presence of jets from hadronically decaying Z or W bosons or from the Higgs boson decaying into a pair of b-quarks. The searches use 139 fb−1 of √ s = 13 TeV proton-proton collisions data collected by the ATLAS detector at the Large Hadron Collider between 2015 and 2018. No deviations from the Standard Model expectations are found, and 95% confdence level exclusion limits are set. Chargino masses ranging from 260 to 520 GeV are excluded for a massless χ˜ 0 1 in chargino pair production models. Degenerate chargino and next-to-lightest neutralino masses ranging from 260 to 420 GeV are excluded for a massless χ˜ 0 1 for χ˜ 0 2 → Zχ˜ 0 1 . For decays through an on-shell Higgs boson and for mass-splitting between χ˜ ± 1 /χ˜ 0 2 and χ˜ 0 1 as small as the Higgs boson mass, mass limits are improved by up to 40 GeV in the range of 200–260 GeV and 280–470 GeV compared to previous ATLAS constraints

Search for single production of vector-like T quarks decaying into Ht or Zt in pp collisions at s√ = 13 TeV with the ATLAS detector

This paper describes a search for the single production of an up-type vector-like quark (T) decaying as T → Ht or T → Zt. The search utilises a dataset of pp collisions at √ s = 13 TeV collected with the ATLAS detector during the 2015–2018 data-taking period of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb−1 . Data are analysed in final states containing a single lepton with multiple jets and b-jets. The presence of boosted heavy resonances in the event is exploited to discriminate the signal from the Standard Model background. No significant excess above the Standard Model expectation is observed, and 95% CL upper limits are set on the production cross section of T quarks in different decay channels. The results are interpreted in several benchmark scenarios to set limits on the mass and universal coupling strength (κ) of the vector-like quark. For singlet T quarks, κ values above 0.53 are excluded for all masses below 2.3 TeV. At a mass of 1.6 TeV, κ values as low as 0.35 are excluded. For T quarks in the doublet scenario, where the production cross section is much lower, κ values above 0.72 are excluded for all masses below 1.7 TeV, and this exclusion is extended to κ above 0.55 for low masses around 1.0 TeV

Differential cross-section measurements of the production of four charged leptons in association with two jets using the ATLAS detector

Diferential cross-sections are measured for the production of four charged leptons in association with two jets. These measurements are sensitive to fnal states in which the jets are produced via the strong interaction as well as to the purely-electroweak vector boson scattering process. The analysis is performed using proton-proton collision data collected by ATLAS at √ s = 13 TeV and with an integrated luminosity of 140 fb−1 . The data are corrected for the efects of detector inefciency and resolution and are compared to stateof-the-art Monte Carlo event generator predictions. The diferential cross-sections are used to search for anomalous weak-boson self-interactions that are induced by dimension-six and dimension-eight operators in Standard Model efective feld theory

Searches for exclusive Higgs and Z boson decays into a vector quarkonium state and a photon using 139 fb^{-1} of ATLAS \sqrt{s}=13 TeV proton–proton collision data

Searches for the exclusive decays of Higgs and Z bosons into a vector quarkonium state and a photon are performed in the \mu ^+\mu ^-\,\gamma final state with a proton–proton collision data sample corresponding to an integrated luminosity of 139 fb^{-1} collected at \sqrt{s}=13 TeV with the ATLAS detector at the CERN Large Hadron Collider. The observed data are compatible with the expected backgrounds. The 95% confidence-level upper limits on the branching fractions of the Higgs boson decays into J/\psi \,\gamma, \psi (2S)\,\gamma, and \Upsilon (1S,2S,3S)\,\gamma are found to be 2.0\times 10^{-4}, 10.5\times 10^{-4}, and (2.5,4.2,3.4)\times 10^{-4}, respectively, assuming Standard Model production of the Higgs boson. The corresponding 95% CL upper limits on the branching fractions of the Z boson decays are 1.2\times 10^{-6}, 2.4\times 10^{-6}, and (1.1,1.3,2.4)\times 10^{-6}. An observed 95% CL interval of (-133,175) is obtained for the \kappa _c/\kappa _\gamma ratio of Higgs boson coupling modifiers, and a 95% CL interval of (-37,40) is obtained for \kappa _b/\kappa _\gamma

Theory and practical based approach to chronic total occlusions

Coronary chronic total occlusions (CTOs) represent the most technically challenging lesion subset that interventional cardiologists face. CTOs are identified in up to one third of patients referred for coronary angiography and remain seriously undertreated with percutaneous techniques. The complexity of these procedures and the suboptimal success rates over a long period of time, along with the perception that CTOs are lesions with limited scope for recanalization, account for the underutilization of CTO Percutaneous Coronary Intervention (PCI). During the last years, dedicated groups of experts in Japan, Europe and United States fostered the development and standardization of modern CTO recanalization techniques, achieving success rates far beyond 90 %, while coping with lesions of increasing complexity. Numerous studies support the rationale of CTO revascularization following documentation of viability and ischemia in the territory distal to the CTO. Successful CTO PCI provide better tolerance in case of future acute coronary syndromes and can significantly improve angina and left ventricular function. Randomized trials are on the way to further explore the prognostic benefit of CTO revascularization. The following review reports on the theory and the most recent advances in the field of CTO recanalization, in an attempt to promote a more balanced approach in patients with chronically occluded coronary arteries

Cutaneous metastasis to the face from colon adenocarcinoma. Case report

BACKGROUND: Facial skin metastases from colorectal cancer are extremely rare and appear several years after resection of the primary tumour. They are an important finding, often being the first sign of metastasis from a previously treated colon cancer. CASE PRESENTATION: We describe a case of a 69 year old patient with cutaneous metastasis to the chin from a previously treated adenocarcinoma of the colon. The patient presented with dyspnoea, pleuritic pain and loss of weight. A chest x-ray revealed a right upper lobe mass of the lung which on subsequent surgical exploration proved to be metastatic from colorectal adenocarcinoma resected three years ago. During the postoperative course, a nodule was noted on the chin and excision biopsy revealed it was also a metastasis from the initial colorectal cancer. Palliative chemoradiotherapy was administered and the patient survived 8 months. CONCLUSION: High index of suspicion is necessary for the early detection of facial cutaneous metastases from colorectal cancer. The aim is to start treatment as soon as possible before widespread visceral metastases occur. Cutaneous metastases from colorectal cancer carry a better prognosis in comparison to those of other epithelial tumours