| 1. |
- Aad, G., et al.
(författare)
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Combination of searches for invisible decays of the Higgs boson using 139 fb−1 of proton-proton collision data at √s=13 TeV collected with the ATLAS experiment
- 2023
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 842
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Tidskriftsartikel (refereegranskat)abstract
- Many extensions of the Standard Model predict the production of dark matter particles at the LHC. Sufficiently light dark matter particles may be produced in decays of the Higgs boson that would appear invisible to the detector. This Letter presents a statistical combination of searches for H→invisible decays where multiple production modes of the Standard Model Higgs boson are considered. These searches are performed with the ATLAS detector using 139 fb−1 of proton–proton collisions at a centre–of–mass energy of at the LHC. In combination with the results at √s=7TeV and 8TeV, an upper limit on the H→invisible branching ratio of 0.107 (0.077) at the 95% confidence level is observed (expected). These results are also interpreted in the context of models where the 125 GeV Higgs boson acts as a portal to dark matter, and limits are set on the scattering cross-section of weakly interacting massive particles and nucleons.
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| 2. |
- Aad, G., et al.
(författare)
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Measurement of the CP properties of Higgs boson interactions with τ-leptons with the ATLAS detector
- 2023
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Ingår i: European Physical Journal C. - : Springer. - 1434-6044 .- 1434-6052. ; 83:7
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Tidskriftsartikel (refereegranskat)abstract
- A study of the charge conjugation and parity (CP) properties of the interaction between the Higgs boson and τ-leptons is presented. The study is based on a measurement of CP-sensitive angular observables defined by the visible decay products of τ-leptons produced in Higgs boson decays. The analysis uses 139 fb−1 of proton–proton collision data recorded at a centre-of-mass energy of √s=13 TeV with the ATLAS detector at the Large Hadron Collider. Contributions from CP-violating interactions between the Higgs boson and τ-leptons are described by a single mixing angle parameter φτ in the generalised Yukawa interaction. Without constraining the H→ττ signal strength to its expected value under the Standard Model hypothesis, the mixing angle φτ is measured to be 9°±16°, with an expected value of 0°±28° at the 68% confidence level. The pure CP-odd hypothesis is disfavoured at a level of 3.4 standard deviations. The results are compatible with the predictions for the Higgs boson in the Standard Model.
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| 3. |
- Aad, G., et al.
(författare)
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Measurement of the production of a W boson in association with a charmed hadron in pp collisions at √s=13 TeV with the ATLAS detector
- 2023
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Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 108:3
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Tidskriftsartikel (refereegranskat)abstract
- The production of a W boson in association with a single charm quark is studied using 140 fb−1 of √s=13 TeV proton-proton collision data collected with the ATLAS detector at the Large Hadron Collider. The charm quark is tagged by the presence of a charmed hadron reconstructed with a secondary-vertex fit. The W boson is reconstructed from the decay to either an electron or a muon and the missing transverse momentum present in the event. The charmed mesons reconstructed are D+→K−π+π+ and D*+→D0π+→(K−π+)π+ and the charge conjugate decays in the fiducial regions where pT(e,μ)>30 GeV, |η(e,μ)|<2.5, pT(D(*))>8 GeV, and |η(D(*))|<2.2. The integrated and normalized differential cross sections as a function of the pseudorapidity of the lepton from the W boson decay, and of the transverse momentum of the charmed hadron, are extracted from the data using a profile likelihood fit. The measured total fiducial cross sections are Results are compared with the predictions of next-to-leading-order quantum chromodynamics calculations performed using state-of-the-art parton distribution functions. Additionally, the ratio of charm to anticharm production cross sections is studied to probe the quark asymmetry. The ratio is found to be . The ratio and cross-section measurements are consistent with the predictions obtained with parton distribution function sets that have a symmetric sea, indicating that any asymmetry in the Bjorken-x region relevant for this measurement is small.
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| 4. |
- Aad, G., et al.
(författare)
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Measurements of differential cross sections of Higgs boson production through gluon fusion in the H → WW*→ eνμν final state at √s=13 TeV with the ATLAS detector
- 2023
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Ingår i: European Physical Journal C. - : Springer. - 1434-6044 .- 1434-6052. ; 83:9
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Tidskriftsartikel (refereegranskat)abstract
- Higgs boson production via gluon–gluon fusion is measured in the WW*→eνμν decay channel. The dataset utilized corresponds to an integrated luminosity of 139 fb−1 collected by the ATLAS detector from √s=13 TeV proton–proton collisions delivered by the Large Hadron Collider between 2015 and 2018. Differential cross sections are measured in a fiducial phase space restricted to the production of at most one additional jet. The results are consistent with Standard Model expectations, derived using different Monte Carlo generators.
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| 5. |
- Aad, G., et al.
(författare)
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Observation of four-top-quark production in the multilepton final state with the ATLAS detector
- 2023
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Ingår i: European Physical Journal C. - : Institute for Ionics. - 1434-6044 .- 1434-6052. ; 83:6
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the observation of four-top-quark () production in proton-proton collisions at the LHC. The analysis is performed using an integrated luminosity of 140 fb−1 at a centre-of-mass energy of 13 TeV collected using the ATLAS detector. Events containing two leptons with the same electric charge or at least three leptons (electrons or muons) are selected. Event kinematics are used to separate signal from background through a multivariate discriminant, and dedicated control regions are used to constrain the dominant backgrounds. The observed (expected) significance of the measured signal with respect to the standard model (SM) background-only hypothesis is 6.1 (4.3) standard deviations. The production cross section is measured to be fb, consistent with the SM prediction of 12.0±2.4 fb within 1.8 standard deviations. Data are also used to set limits on the three-top-quark production cross section, being an irreducible background not measured previously, and to constrain the top-Higgs Yukawa coupling and effective field theory operator coefficients that affect production.
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| 6. |
- Aad, G., et al.
(författare)
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Search for supersymmetry in final states with missing transverse momentum and three or more b-jets in 139 fb-1 of proton-proton collisions at √s=13 TeV with the ATLAS detector
- 2023
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Ingår i: European Physical Journal C. - : Springer. - 1434-6044 .- 1434-6052. ; 83:7
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Tidskriftsartikel (refereegranskat)abstract
- A search for supersymmetry involving the pair production of gluinos decaying via off-shell third-generation squarks into the lightest neutralino () is reported. It exploits LHC proton–proton collision data at a centre-of-mass energy √s=13 TeV with an integrated luminosity of 139 fb−1 collected with the ATLAS detector from 2015 to 2018. The search uses events containing large missing transverse momentum, up to one electron or muon, and several energetic jets, at least three of which must be identified as containing b-hadrons. Both a simple kinematic event selection and an event selection based upon a deep neural-network are used. No significant excess above the predicted background is found. In simplified models involving the pair production of gluinos that decay via off-shell top (bottom) squarks, gluino masses less than 2.44 TeV (2.35 TeV) are excluded at 95% CL for a massless . Limits are also set on the gluino mass in models with variable branching ratios for gluino decays to , and .
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| 7. |
- Aad, G., et al.
(författare)
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Search in diphoton and dielectron final states for displaced production of Higgs or Z bosons with the ATLAS detector in √s=13 TeV pp collisions
- 2023
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Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 108:1
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Tidskriftsartikel (refereegranskat)abstract
- A search is presented for displaced production of Higgs bosons or Z bosons, originating from the decay of a neutral long-lived particle (LLP) and reconstructed in the decay modes H→γγ and Z→ee. The analysis uses the full Run 2 dataset of proton-proton collisions delivered by the LHC at an energy of √s=13 TeV between 2015 and 2018 and recorded by the ATLAS detector, corresponding to an integrated luminosity of 139 fb−1. Exploiting the capabilities of the ATLAS liquid argon calorimeter to precisely measure the arrival times and trajectories of electromagnetic objects, the analysis searches for the signature of pairs of photons or electrons which arise from a common displaced vertex and which arrive after some delay at the calorimeter. The results are interpreted in a gauge-mediated supersymmetry breaking model with pair-produced Higgsinos that decay to LLPs, and each LLP subsequently decays into either a Higgs boson or a Z boson. The final state includes at least two particles that escape direct detection, giving rise to missing transverse momentum. No significant excess is observed above the background expectation. The results are used to set upper limits on the cross section for Higgsino pair production, up to a mass of 369 (704) GeV for decays with 100% branching ratio of to Higgs (Z) bosons for a lifetime of 2 ns. A model-independent limit is also set on the production of pairs of photons or electrons with a significant delay in arrival at the calorimeter.
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| 8. |
- Backman, Filip, 1991-, et al.
(författare)
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New techniques for jet calibration with the ATLAS detector
- 2023
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Ingår i: European Physical Journal C. - : Springer Nature. - 1434-6044 .- 1434-6052. ; 83:8
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Tidskriftsartikel (refereegranskat)abstract
- A determination of the jet energy scale is presented using proton-proton collision data with a centre-of-mass energy of root s = 13 TeV, corresponding to an integrated luminosity of 140 fb(-1) collected using the ATLAS detector at the LHC. Jets are reconstructed using the ATLAS particle-flow method that combines charged-particle tracks and topo-clusters formed from energy deposits in the calorimeter cells. The anti-kt jet algorithm with radius parameter R = 0.4 is used to define the jet. Novel jet energy scale calibration strategies developed for the LHC Run 2 are reported that lay the foundation for the jet calibration in Run 3. Jets are calibrated with a series of simulation-based corrections, including state-of-the-art techniques in jet calibration such as machine learning methods and novel in situ calibrations to achieve better performance than the baseline calibration derived using up to 81 fb(-1) of Run 2 data. The performance of these new techniques is then examined in the in situ measurements by exploiting the transverse momentum balance between a jet and a reference object. The b-quark jet energy scale using particle flow jets is measured for the first time with around 1% precision using gamma+jet events.
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| 9. |
- Backman, Max, 1987-
(författare)
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Spatial immune analyses in clinical cancer tissue
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cancer is a leading cause of premature death and lung cancer is the deadliest cancer type, with non-small cell lung cancer (NSCLC) representing 85% of lung cancer cases. Despite promising development in cancer treatment in recent decades, overall prognosis is poor. The aim of this thesis was to explore novel techniques in protein visualization in clinical cancer tissue to better our understanding of cancer immunity and to discover new biomarkers for improved cancer diagnostics.In Paper I traditional immunohistochemistry (IHC) was compared to the in-situ proximity ligation assay (isPLA). Both techniques were applied to stain 12 proteins in 39 cell lines and 37 tissue types. Two different antibodies were used in the IHC assay and in the isPLA, where binding by both antibodies is required to generate detection signals. The comparison of staining patterns showed that the isPLA presents a valuable alternative to traditional IHC.In Paper II cancer tissue from 357 NSCLC patients was immunophenotyped through IHC annotations of 11 different immune markers. A distinct group of cases with a signature of NK cells and/or plasma cells had favorable prognosis despite significantly lower T-cell activation signatures. This study provides a detailed description of the immune landscape in NSCLC, extending previous concepts, and highlights plasma and NK-cells as potential biomarkers for further validation.In Paper III a multiplex-multispectral pipeline was established to explore three immune marker panels in a NSCLC cohort, spatially quantifying 13 immune cell types. The immune composition of NSCLC was analyzed for the prognostic relevance of immune cell coordination. Cell densities and distances were found to contribute independently to prognosis, indicating that spatial information on local immune cell infiltration is crucial for understanding tumor immunity.In Paper IV an extensive characterization of the immune cell landscape of colon cancer identified a prognostic signature based on the ratio of CD8+ lymphocytes to CD68+CD163+ macrophages. This signature was superior to the state-of-the-art ‘Immunoscore’, and was also associated with longer survival when analyzed in other common cancer types. This presents a promising immunological biomarker that warrants further validation as a prognostic and predictive signature in common cancers.In summary, this thesis presents an in-depth study of immune cell infiltration in several cancer types to better understand cancer immunity. Through novel techniques and spatial metrics, we describe immunophenotypes that might contribute to cancer classification and prognostication. The identified immune phenomena may also present alternative treatment targets to overcome resistance to immunotherapy.
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| 10. |
- Backman, Max, 1987-, et al.
(författare)
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Spatial immunophenotyping of the tumor microenvironment in non-small cell lung cancer
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: Immune cells in the tumor microenvironment are associated with prognosis and response to therapy. We aimed to comprehensively characterize the spatial immune phenotypes in the mutational and clinicopathological background of non-small cell lung cancer (NSCLC).Methods: We established a multiplexed fluorescence multispectral imaging pipeline to spatially quantify 13 immune cell subsets in 359 NSCLC cases: CD4 effector cells (CD4 Eff), CD4 regulatory cells (CD4 Treg), CD8 effector cells (CD8 Eff), CD8 regulatory cells (CD8 Treg), B-cells, NK-cells, NKT-cells, M1 macrophages (M1), CD163+ myeloid cells (CD163), M2 macrophages (M2), immature dendritic cells (iDCs), mature dendritic cells (mDCs), and plasmacytoid dendritic cells (pDCs). Results: CD4 Eff cells, CD8 Eff cells, and M1 macrophages were the most abundant immune cells invading the tumor cell compartment and indicated a patient group with a favorable prognosis in the cluster analysis. Likewise, single densities of lymphocytic subsets (CD4 Eff, CD4 Treg, CD8 Treg, and B-cells), as well as pDCs, were independently associated with longer survival. However, when these immune cells were located close to CD8 Treg cells, the favorable impact was attenuated. In the multivariate Cox regression model including cell densities and distances, the densities of M1 and CD163 cells and distances between cells (CD8 Treg–B-cells, CD8 Eff–cancer cells, and B-cells–CD4 Treg) demonstrated positive prognostic impact, while short M2–M1 distances were prognostically unfavorable.Conclusion: We present a unique spatial profile of the in situ immune cell landscape in NSCLC as a publicly available data set. Cell densities and cell distances contribute independently to prognostic information on clinical outcomes, suggesting that spatial information is also crucial for diagnostic use.
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