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Observation of Single-Top-Quark Production in Association with a Photon Using the ATLAS Detector. PHYSICAL REVIEW LETTERS 2023; 131:181901. [PMID: 37977601 DOI: 10.1103/physrevlett.131.181901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 08/03/2023] [Accepted: 08/09/2023] [Indexed: 11/19/2023]
Abstract
This Letter reports the observation of single top quarks produced together with a photon, which directly probes the electroweak coupling of the top quark. The analysis uses 139 fb^{-1} of 13 TeV proton-proton collision data collected with the ATLAS detector at the Large Hadron Collider. Requiring a photon with transverse momentum larger than 20 GeV and within the detector acceptance, the fiducial cross section is measured to be 688±23(stat) _{-71}^{+75}(syst) fb, to be compared with the standard model prediction of 515_{-42}^{+36} fb at next-to-leading order in QCD.
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2
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Tests of Light-Lepton Universality in Angular Asymmetries of B^{0}→D^{*-}ℓν Decays. PHYSICAL REVIEW LETTERS 2023; 131:181801. [PMID: 37977641 DOI: 10.1103/physrevlett.131.181801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 09/29/2023] [Indexed: 11/19/2023]
Abstract
We present the first comprehensive tests of the universality of the light leptons in the angular distributions of semileptonic B^{0}-meson decays to charged spin-1 charmed mesons. We measure five angular-asymmetry observables as functions of the decay recoil that are sensitive to lepton-universality-violating contributions. We use events where one neutral B is fully reconstructed in ϒ(4S)→BB[over ¯] decays in data corresponding to 189 fb^{-1} integrated luminosity from electron-positron collisions collected with the Belle II detector. We find no significant deviation from the standard model expectations.
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3
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Author Correction: A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery. Nature 2023; 623:E5. [PMID: 37853131 PMCID: PMC10620074 DOI: 10.1038/s41586-023-06248-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2023]
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4
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Precise Measurement of the D_{s}^{+} Lifetime at Belle II. PHYSICAL REVIEW LETTERS 2023; 131:171803. [PMID: 37955504 DOI: 10.1103/physrevlett.131.171803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 09/14/2023] [Indexed: 11/14/2023]
Abstract
We measure the lifetime of the D_{s}^{+} meson using a data sample of 207 fb^{-1} collected by the Belle II experiment running at the SuperKEKB asymmetric-energy e^{+}e^{-} collider. The lifetime is determined by fitting the decay-time distribution of a sample of 116×10^{3} D_{s}^{+}→ϕπ^{+} decays. Our result is τ_{D_{s}^{+}}=(499.5±1.7±0.9) fs, where the first uncertainty is statistical and the second is systematic. This result is significantly more precise than previous measurements.
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5
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Observation of the γγ→ττ Process in Pb+Pb Collisions and Constraints on the τ-Lepton Anomalous Magnetic Moment with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2023; 131:151802. [PMID: 37897746 DOI: 10.1103/physrevlett.131.151802] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 07/07/2022] [Indexed: 10/30/2023]
Abstract
This Letter reports the observation of τ-lepton-pair production in ultraperipheral lead-lead collisions Pb+Pb→Pb(γγ→ττ)Pb and constraints on the τ-lepton anomalous magnetic moment a_{τ}. The dataset corresponds to an integrated luminosity of 1.44 nb^{-1} of LHC Pb+Pb collisions at sqrt[s_{NN}]=5.02 TeV recorded by the ATLAS experiment in 2018. Selected events contain one muon from a τ-lepton decay, an electron or charged-particle track(s) from the other τ-lepton decay, little additional central-detector activity, and no forward neutrons. The γγ→ττ process is observed in Pb+Pb collisions with a significance exceeding 5 standard deviations and a signal strength of μ_{ττ}=1.03_{-0.05}^{+0.06} assuming the standard model value for a_{τ}. To measure a_{τ}, a template fit to the muon transverse-momentum distribution from τ-lepton candidates is performed, using a dimuon (γγ→μμ) control sample to constrain systematic uncertainties. The observed 95% confidence-level interval for a_{τ} is -0.057
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6
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Search for a τ^{+}τ^{-} Resonance in e^{+}e^{-}→μ^{+}μ^{-}τ^{+}τ^{-} Events with the Belle II Experiment. PHYSICAL REVIEW LETTERS 2023; 131:121802. [PMID: 37802942 DOI: 10.1103/physrevlett.131.121802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 08/08/2023] [Indexed: 10/08/2023]
Abstract
We report the first search for a nonstandard-model resonance decaying into τ pairs in e^{+}e^{-}→μ^{+}μ^{-}τ^{+}τ^{-} events in the 3.6-10 GeV/c^{2} mass range. We use a 62.8 fb^{-1} sample of e^{+}e^{-} collisions collected at a center-of-mass energy of 10.58 GeV by the Belle II experiment at the SuperKEKB collider. The analysis probes three different models predicting a spin-1 particle coupling only to the heavier lepton families, a Higgs-like spin-0 particle that couples preferentially to charged leptons (leptophilic scalar), and an axionlike particle, respectively. We observe no evidence for a signal and set exclusion limits at 90% confidence level on the product of cross section and branching fraction into τ pairs, ranging from 0.7 to 24 fb, and on the couplings of these processes. We obtain world-leading constraints on the couplings for the leptophilic scalar model for masses above 6.5 GeV/c^{2} and for the axionlike particle model over the entire mass range.
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7
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Measurement of CP Violation in B^{0}→K_{S}^{0}π^{0} Decays at Belle II. PHYSICAL REVIEW LETTERS 2023; 131:111803. [PMID: 37774261 DOI: 10.1103/physrevlett.131.111803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 07/26/2023] [Indexed: 10/01/2023]
Abstract
We report a measurement of the CP-violating parameters C and S in B^{0}→K_{S}^{0}π^{0} decays at Belle II using a sample of 387×10^{6} BB[over ¯] events recorded in e^{+}e^{-} collisions at a center-of-mass energy corresponding to the ϒ(4S) resonance. These parameters are determined by fitting the proper decay-time distribution of a sample of 415 signal events. We obtain C=-0.04_{-0.15}^{+0.14}±0.05 and S=0.75_{-0.23}^{+0.20}±0.04, where the first uncertainties are statistical and the second are systematic.
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8
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Strong Constraints on Jet Quenching in Centrality-Dependent p+Pb Collisions at 5.02 TeV from ATLAS. PHYSICAL REVIEW LETTERS 2023; 131:072301. [PMID: 37656838 DOI: 10.1103/physrevlett.131.072301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 10/04/2022] [Accepted: 11/17/2022] [Indexed: 09/03/2023]
Abstract
Jet quenching is the process of color-charged partons losing energy via interactions with quark-gluon plasma droplets created in heavy-ion collisions. The collective expansion of such droplets is well described by viscous hydrodynamics. Similar evidence of collectivity is consistently observed in smaller collision systems, including pp and p+Pb collisions. In contrast, while jet quenching is observed in Pb+Pb collisions, no evidence has been found in these small systems to date, raising fundamental questions about the nature of the system created in these collisions. The ATLAS experiment at the Large Hadron Collider has measured the yield of charged hadrons correlated with reconstructed jets in 0.36 nb^{-1} of p+Pb and 3.6 pb^{-1} of pp collisions at 5.02 TeV. The yields of charged hadrons with p_{T}^{ch}>0.5 GeV near and opposite in azimuth to jets with p_{T}^{jet}>30 or 60 GeV, and the ratios of these yields between p+Pb and pp collisions, I_{pPb}, are reported. The collision centrality of p+Pb events is categorized by the energy deposited by forward neutrons from the struck nucleus. The I_{pPb} values are consistent with unity within a few percent for hadrons with p_{T}^{ch}>4 GeV at all centralities. These data provide new, strong constraints that preclude almost any parton energy loss in central p+Pb collisions.
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9
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Search for Heavy Neutral Leptons in Decays of W Bosons Using a Dilepton Displaced Vertex in sqrt[s]=13 TeV pp Collisions with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2023; 131:061803. [PMID: 37625051 DOI: 10.1103/physrevlett.131.061803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 08/08/2022] [Indexed: 08/27/2023]
Abstract
A search for a long-lived, heavy neutral lepton (N) in 139 fb^{-1} of sqrt[s]=13 TeV pp collision data collected by the ATLAS detector at the Large Hadron Collider is reported. The N is produced via W→Nμ or W→Ne and decays into two charged leptons and a neutrino, forming a displaced vertex. The N mass is used to discriminate between signal and background. No signal is observed, and limits are set on the squared mixing parameters of the N with the left-handed neutrino states for the N mass range 3 GeV
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10
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Test of Light-Lepton Universality in the Rates of Inclusive Semileptonic B-Meson Decays at Belle II. PHYSICAL REVIEW LETTERS 2023; 131:051804. [PMID: 37595249 DOI: 10.1103/physrevlett.131.051804] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 05/03/2023] [Accepted: 05/11/2023] [Indexed: 08/20/2023]
Abstract
We present the first measurement of the ratio of branching fractions of inclusive semileptonic B-meson decays, R(X_{e/μ})=B(B→Xeν)/B(B→Xμν), a precision test of electron-muon universality, using data corresponding to 189 fb^{-1} from electron-positron collisions collected with the Belle II detector. In events where the partner B meson is fully reconstructed, we use fits to the lepton momentum spectra above 1.3 GeV/c to obtain R(X_{e/μ})=1.007±0.009(stat)±0.019(syst), which is the most precise lepton-universality test of its kind and agrees with the standard-model expectation.
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11
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First Measurement of the Michel Parameter ξ^{'} in the τ^{-}→μ^{-}ν[over ¯]_{μ}ν_{τ} Decay at Belle. PHYSICAL REVIEW LETTERS 2023; 131:021801. [PMID: 37505960 DOI: 10.1103/physrevlett.131.021801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 06/06/2023] [Indexed: 07/30/2023]
Abstract
We report the first measurement of the Michel parameter ξ^{'} in the τ^{-}→μ^{-}ν[over ¯]_{μ}ν_{τ} decay with a new method proposed just recently. The measurement is based on the reconstruction of the τ^{-}→μ^{-}ν[over ¯]_{μ}ν_{τ} events with subsequent muon decay in flight in the Belle central drift chamber. The analyzed data sample of 988 fb^{-1} collected by the Belle detector corresponds to approximately 912×10^{6} τ^{+}τ^{-} pairs. We measure ξ^{'}=0.22±0.94(stat)±0.42(syst), which is in agreement with the standard model prediction of ξ^{'}=1. Statistical uncertainty dominates in this study, being a limiting factor, while systematic uncertainty is well under control. Our analysis proved the practicability of this promising method and its prospects for further precise measurement in future experiments.
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12
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High-cholesterol diet in combination with hydroxypropyl-beta-cyclodextrin induces NASH-like disorders in the liver of rats. Physiol Res 2023; 72:371-382. [PMID: 37449749 PMCID: PMC10668992 DOI: 10.33549/physiolres.934981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 02/22/2023] [Indexed: 08/26/2023] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is a general term for fatty liver disease not caused by viruses or alcohol. Fibrotic hepatitis, cirrhosis, and hepatocellular carcinoma can develop. The recent increase in NAFLD incidence worldwide has stimulated drug development efforts. However, there is still no approved treatment. This may be due in part to the fact that non-alcoholic steatohepatitis (NASH) pathogenesis is very complex, and its mechanisms are not well understood. Studies with animals are very important for understanding the pathogenesis. Due to the close association between the establishment of human NASH pathology and metabolic syndrome, several animal models have been reported, especially in the context of overnutrition. In this study, we investigated the induction of NASH-like pathology by enhancing cholesterol absorption through treatment with hydroxypropyl-beta-cyclodextrin (CDX). Female Sprague-Dawley rats were fed a normal diet with normal water (control group); a high-fat (60 kcal%), cholesterol (1.25 %), and cholic acid (0.5 %) diet with normal water (HFCC group); or HFCC diet with 2 % CDX water (HFCC+CDX group) for 16 weeks. Compared to the control group, the HFCC and HFCC+CDX groups showed increased blood levels of total cholesterol, aspartate aminotransferase, and alanine aminotransferase. At autopsy, parameters related to hepatic lipid synthesis, oxidative stress, inflammation, and fibrosis were elevated, suggesting the development of NAFLD/NASH. Elevated levels of endoplasmic reticulum stress-related genes were evident in the HFCC+CDX group. In the novel rat model, excessive cholesterol intake and accelerated absorption contributed to NAFLD/NASH pathogenesis.
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13
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Search for the Lepton Flavor Violating Decays B^{+}→K^{+}τ^{±}ℓ^{∓} (ℓ=e, μ) at Belle. PHYSICAL REVIEW LETTERS 2023; 130:261802. [PMID: 37450824 DOI: 10.1103/physrevlett.130.261802] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 05/04/2023] [Indexed: 07/18/2023]
Abstract
We present a search for the lepton flavor violating decays B^{+}→K^{+}τ^{±}ℓ^{∓}, with ℓ=(e,μ), using the full data sample of 772×10^{6} BB[over ¯] pairs recorded by the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. We use events in which one B meson is fully reconstructed in a hadronic decay mode. We find no evidence for B^{±}→K^{±}τℓ decays and set upper limits on their branching fractions at the 90% confidence level in the (1-3)×10^{-5} range. The obtained limits are the world's best results.
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Search for an Invisible Z^{'} in a Final State with Two Muons and Missing Energy at Belle II. PHYSICAL REVIEW LETTERS 2023; 130:231801. [PMID: 37354391 DOI: 10.1103/physrevlett.130.231801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 04/19/2023] [Indexed: 06/26/2023]
Abstract
The L_{μ}-L_{τ} extension of the standard model predicts the existence of a lepton-flavor-universality-violating Z^{'} boson that couples only to the heavier lepton families. We search for such a Z^{'} through its invisible decay in the process e^{+}e^{-}→μ^{+}μ^{-}Z^{'}. We use a sample of electron-positron collisions at a center-of-mass energy of 10.58 GeV collected by the Belle II experiment in 2019-2020, corresponding to an integrated luminosity of 79.7 fb^{-1}. We find no excess over the expected standard-model background. We set 90%-confidence-level upper limits on the cross section for this process as well as on the coupling of the model, which ranges from 3×10^{-3} at low Z^{'} masses to 1 at Z^{'} masses of 8 GeV/c^{2}.
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First Measurement of the B^{+}→π^{+}π^{0}π^{0} Branching Fraction and CP Asymmetry. PHYSICAL REVIEW LETTERS 2023; 130:181804. [PMID: 37204904 DOI: 10.1103/physrevlett.130.181804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 03/27/2023] [Indexed: 05/21/2023]
Abstract
We study B^{+}→π^{+}π^{0}π^{0} using 711 fb^{-1} of data collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. We measure an inclusive branching fraction of (19.0±1.5±1.4)×10^{-6} and an inclusive CP asymmetry of (9.2±6.8±0.7)%, where the first uncertainties are statistical and the second are systematic, and a B^{+}→ρ(770)^{+}π^{0} branching fraction of (11.2±1.1±0.9_{-1.6}^{+0.8})×10^{-6}, where the third uncertainty is due to possible interference with B^{+}→ρ(1450)^{+}π^{0}. We present the first observation of a structure around 1 GeV/c^{2} in the π^{0}π^{0} mass spectrum, with a significance of 6.4σ, and measure a branching fraction to be (6.9±0.9±0.6)×10^{-6}. We also report a measurement of local CP asymmetry in this structure.
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16
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Search for Lepton-Flavor-Violating τ Decays to a Lepton and an Invisible Boson at Belle II. PHYSICAL REVIEW LETTERS 2023; 130:181803. [PMID: 37204890 DOI: 10.1103/physrevlett.130.181803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 02/23/2023] [Indexed: 05/21/2023]
Abstract
We search for lepton-flavor-violating τ^{-}→e^{-}α and τ^{-}→μ^{-}α decays, where α is an invisible spin-0 boson. The search uses electron-positron collisions at 10.58 GeV center-of-mass energy with an integrated luminosity of 62.8 fb^{-1}, produced by the SuperKEKB collider and collected with the Belle II detector. We search for an excess in the lepton-energy spectrum of the known τ^{-}→e^{-}ν[over ¯]_{e}ν_{τ} and τ^{-}→μ^{-}ν[over ¯]_{μ}ν_{τ} decays. We report 95% confidence-level upper limits on the branching-fraction ratio B(τ^{-}→e^{-}α)/B(τ^{-}→e^{-}ν[over ¯]_{e}ν_{τ}) in the range (1.1-9.7)×10^{-3} and on B(τ^{-}→μ^{-}α)/B(τ^{-}→μ^{-}ν[over ¯]_{μ}ν_{τ}) in the range (0.7-12.2)×10^{-3} for α masses between 0 and 1.6 GeV/c^{2}. These results provide the most stringent bounds on invisible boson production from τ decays.
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Unilateral nephrectomized SHR/NDmcr-cp rat shows a progressive decline of glomerular filtration with tubular interstitial lesions. Physiol Res 2023; 72:209-220. [PMID: 37159855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023] Open
Abstract
In patients with diabetic kidney disease (DKD), the estimated glomerular filtration rate (eGFR) or creatinine clearance rate (Ccr) is always used as an index of decline in renal function. However, there are few animal models of DKD that could be used to evaluate renal function based on GFR or Ccr. For this reason, it is desirable to develop animal models to assess renal function, which could also be used for the evaluation of novel therapeutic agents for DKD. Therefore, we aimed to develop such animal model of DKD by using spontaneously hypertensive rat (SHR)/NDmcr-cp (cp/cp) rats with the characteristics of obese type 2 diabetes and metabolic syndrome. As a result, we have found that unilateral nephrectomy (UNx) caused a chronic Ccr decline, development of glomerular sclerosis, tubular lesions, and tubulointerstitial fibrosis, accompanied by renal anemia. Moreover, losartan-mixed diet suppressed the Ccr decline in UNx-performed SHR/NDmcr-cp rats (UNx-SHR/cp rats), with improvement in renal anemia and histopathological changes. These results suggest that UNx-SHR/cp rats could be used as a DKD model for evaluating the efficacy of therapeutic agents based on suppression of renal function decline.
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18
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First Observation of Λπ^{+} and Λπ^{-} Signals near the K[over ¯]N(I=1) Mass Threshold in Λ_{c}^{+}→Λπ^{+}π^{+}π^{-} Decay. PHYSICAL REVIEW LETTERS 2023; 130:151903. [PMID: 37115880 DOI: 10.1103/physrevlett.130.151903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 03/15/2023] [Indexed: 06/19/2023]
Abstract
Using the data sample of 980 fb^{-1} collected with the Belle detector operating at the KEKB asymmetric-energy e^{+}e^{-} collider, we present the results of an investigation of the Λπ^{+} and Λπ^{-} invariant mass distributions looking for substructure in the decay Λ_{c}^{+}→Λπ^{+}π^{+}π^{-}. We find a significant signal in each mass distribution. When interpreted as resonances, we find for the Λπ^{+} (Λπ^{-}) combination a mass of 1434.3±0.6(stat)±0.9(syst) MeV/c^{2} [1438.5±0.9(stat)±2.5(syst) MeV/c^{2}], an intrinsic width of 11.5±2.8(stat)±5.3(syst) MeV/c^{2} [33.0±7.5(stat)±23.6(syst) MeV/c^{2}] with a significance of 7.5σ (6.2σ). As these two signals are very close to the K[over ¯]N threshold, we also investigate the possibility of a K[over ¯]N cusp, and find that we cannot discriminate between these two interpretations due to the limited size of the data sample.
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Observation of e^{+}e^{-}→ωχ_{bJ}(1P) and Search for X_{b}→ωϒ(1S) at sqrt[s] near 10.75 GeV. PHYSICAL REVIEW LETTERS 2023; 130:091902. [PMID: 36930912 DOI: 10.1103/physrevlett.130.091902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 01/25/2023] [Indexed: 06/18/2023]
Abstract
We study the processes e^{+}e^{-}→ωχ_{bJ}(1P) (J=0, 1, or 2) using samples at center-of-mass energies sqrt[s]=10.701, 10.745, and 10.805 GeV, corresponding to 1.6, 9.8, and 4.7 fb^{-1} of integrated luminosity, respectively. These data were collected with the Belle II detector during special operations of the SuperKEKB collider above the ϒ(4S) resonance. We report the first observation of ωχ_{bJ}(1P) signals at sqrt[s]=10.745 GeV. By combining Belle II data with Belle results at sqrt[s]=10.867 GeV, we find energy dependencies of the Born cross sections for e^{+}e^{-}→ωχ_{b1,b2}(1P) to be consistent with the shape of the ϒ(10753) state. These data indicate that the internal structures of the ϒ(10753) and ϒ(10860) states may differ. Including data at sqrt[s]=10.653 GeV, we also search for the bottomonium equivalent of the X(3872) state decaying into ωϒ(1S). No significant signal is observed for masses between 10.45 and 10.65 GeV/c^{2}.
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Measurement of the Λ_{c}^{+} Lifetime. PHYSICAL REVIEW LETTERS 2023; 130:071802. [PMID: 36867815 DOI: 10.1103/physrevlett.130.071802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 07/25/2022] [Indexed: 06/18/2023]
Abstract
An absolute measurement of the Λ_{c}^{+} lifetime is reported using Λ_{c}^{+}→pK^{-}π^{+} decays in events reconstructed from data collected by the Belle II experiment at the SuperKEKB asymmetric-energy electron-positron collider. The total integrated luminosity of the data sample, which was collected at center-of-mass energies at or near the ϒ(4S) resonance, is 207.2 fb^{-1}. The result, τ(Λ_{c}^{+})=203.20±0.89±0.77 fs, where the first uncertainty is statistical and the second systematic, is the most precise measurement to date and is consistent with previous determinations.
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Search for a Dark Photon and an Invisible Dark Higgs Boson in μ^{+}μ^{-} and Missing Energy Final States with the Belle II Experiment. PHYSICAL REVIEW LETTERS 2023; 130:071804. [PMID: 36867830 DOI: 10.1103/physrevlett.130.071804] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Accepted: 11/29/2022] [Indexed: 06/18/2023]
Abstract
The dark photon A^{'} and the dark Higgs boson h^{'} are hypothetical particles predicted in many dark sector models. We search for the simultaneous production of A^{'} and h^{'} in the dark Higgsstrahlung process e^{+}e^{-}→A^{'}h^{'} with A^{'}→μ^{+}μ^{-} and h^{'} invisible in electron-positron collisions at a center-of-mass energy of 10.58 GeV in data collected by the Belle II experiment in 2019. With an integrated luminosity of 8.34 fb^{-1}, we observe no evidence for signal. We obtain exclusion limits at 90% Bayesian credibility in the range of 1.7-5.0 fb on the cross section and in the range of 1.7×10^{-8}-200×10^{-8} on the effective coupling ϵ^{2}×α_{D} for the A^{'} mass in the range of 4.0 GeV/c^{2}<M_{A^{'}}<9.7 GeV/c^{2} and for the h^{'} mass M_{h^{'}}<M_{A^{'}}, where ϵ is the mixing strength between the standard model and the dark photon and α_{D} is the coupling of the dark photon to the dark Higgs boson. Our limits are the first in this mass range.
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Observation of WWW Production in pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2022; 129:061803. [PMID: 36018638 DOI: 10.1103/physrevlett.129.061803] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 06/23/2022] [Indexed: 06/15/2023]
Abstract
This Letter reports the observation of WWW production and a measurement of its cross section using 139 fb^{-1} of proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. Events with two same-sign leptons (electrons or muons) and at least two jets, as well as events with three charged leptons, are selected. A multivariate technique is then used to discriminate between signal and background events. Events from WWW production are observed with a significance of 8.0 standard deviations, where the expectation is 5.4 standard deviations. The inclusive WWW production cross section is measured to be 820±100 (stat)±80 (syst) fb, approximately 2.6 standard deviations from the predicted cross section of 511±18 fb calculated at next-to-leading-order QCD and leading-order electroweak accuracy.
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A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery. Nature 2022; 607:52-59. [PMID: 35788192 PMCID: PMC9259483 DOI: 10.1038/s41586-022-04893-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 05/23/2022] [Indexed: 11/16/2022]
Abstract
The standard model of particle physics1-4 describes the known fundamental particles and forces that make up our Universe, with the exception of gravity. One of the central features of the standard model is a field that permeates all of space and interacts with fundamental particles5-9. The quantum excitation of this field, known as the Higgs field, manifests itself as the Higgs boson, the only fundamental particle with no spin. In 2012, a particle with properties consistent with the Higgs boson of the standard model was observed by the ATLAS and CMS experiments at the Large Hadron Collider at CERN10,11. Since then, more than 30 times as many Higgs bosons have been recorded by the ATLAS experiment, enabling much more precise measurements and new tests of the theory. Here, on the basis of this larger dataset, we combine an unprecedented number of production and decay processes of the Higgs boson to scrutinize its interactions with elementary particles. Interactions with gluons, photons, and W and Z bosons-the carriers of the strong, electromagnetic and weak forces-are studied in detail. Interactions with three third-generation matter particles (bottom (b) and top (t) quarks, and tau leptons (τ)) are well measured and indications of interactions with a second-generation particle (muons, μ) are emerging. These tests reveal that the Higgs boson discovered ten years ago is remarkably consistent with the predictions of the theory and provide stringent constraints on many models of new phenomena beyond the standard model.
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Measurement of Two-Particle Correlations of Hadrons in e^{+}e^{-} Collisions at Belle. PHYSICAL REVIEW LETTERS 2022; 128:142005. [PMID: 35476485 DOI: 10.1103/physrevlett.128.142005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 03/14/2022] [Indexed: 06/14/2023]
Abstract
The measurement of two-particle angular correlation functions in high-multiplicity e^{+}e^{-} collisions at sqrt[s]=10.52 GeV is reported. In this study, the 89.5 fb^{-1} of hadronic e^{+}e^{-} annihilation data collected by the Belle detector at KEKB are used. Two-particle angular correlation functions are measured in the full relative azimuthal angle (Δϕ) and three units of pseudorapidity (Δη), defined by either the electron beam axis or the event-shape thrust axis, and are studied as a function of charged-particle multiplicity. The measurement in the thrust axis analysis, with mostly outgoing quark pairs determining the reference axis, is sensitive to the region of additional soft gluon emissions. No significant anisotropic collective behavior is observed with either coordinate analyses. Near-side jet correlations appear to be absent in the thrust axis analysis. The measurements are compared to predictions from various event generators and are expected to provide new constraints to the phenomenological models in the low-energy regime.
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Search for a Light Higgs Boson in Single-Photon Decays of ϒ(1S) Using ϒ(2S)→π^{+}π^{-}ϒ(1S) Tagging Method. PHYSICAL REVIEW LETTERS 2022; 128:081804. [PMID: 35275679 DOI: 10.1103/physrevlett.128.081804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 01/26/2022] [Indexed: 06/14/2023]
Abstract
We search for a light Higgs boson (A^{0}) decaying into a τ^{+}τ^{-} or μ^{+}μ^{-} pair in the radiative decays of ϒ(1S). The production of ϒ(1S) mesons is tagged by ϒ(2S)→π^{+}π^{-}ϒ(1S) transitions, using 158×10^{6} ϒ(2S) events accumulated with the Belle detector at the KEKB asymmetric energy electron-positron collider. No significant A^{0} signals in the mass range from the τ^{+}τ^{-} or μ^{+}μ^{-} threshold to 9.2 GeV/c^{2} are observed. We set the upper limits at 90% credibility level (C.L.) on the product branching fractions for ϒ(1S)→γA^{0} and A^{0}→τ^{+}τ^{-} varying from 3.8×10^{-6} to 1.5×10^{-4}. Our results represent an approximately twofold improvement on the current world best upper limits for the ϒ(1S)→γA^{0}(→τ^{+}τ^{-}) production. For A^{0}→μ^{+}μ^{-}, the upper limits on the product branching fractions for ϒ(1S)→γA^{0} and A^{0}→μ^{+}μ^{-} are at the same level as the world average limits, and vary from 3.1×10^{-7} to 1.6×10^{-5}. The upper limits at 90% credibility level on the Yukawa coupling f_{ϒ(1S)} and mixing angle sinθ_{A^{0}} are also given.
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Search for Lepton-Flavor Violation in Z-Boson Decays with τ Leptons with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2021; 127:271801. [PMID: 35061407 DOI: 10.1103/physrevlett.127.271801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 10/05/2021] [Indexed: 06/14/2023]
Abstract
A search for lepton-flavor-violating Z→eτ and Z→μτ decays with pp collision data recorded by the ATLAS detector at the LHC is presented. This analysis uses 139 fb^{-1} of Run 2 pp collisions at sqrt[s]=13 TeV and is combined with the results of a similar ATLAS search in the final state in which the τ lepton decays hadronically, using the same data set as well as Run 1 data. The addition of leptonically decaying τ leptons significantly improves the sensitivity reach for Z→ℓτ decays. The Z→ℓτ branching fractions are constrained in this analysis to B(Z→eτ)<7.0×10^{-6} and B(Z→μτ)<7.2×10^{-6} at 95% confidence level. The combination with the previously published analyses sets the strongest constraints to date: B(Z→eτ)<5.0×10^{-6} and B(Z→μτ)<6.5×10^{-6} at 95% confidence level.
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Precise Measurement of the D^{0} and D^{+} Lifetimes at Belle II. PHYSICAL REVIEW LETTERS 2021; 127:211801. [PMID: 34860075 DOI: 10.1103/physrevlett.127.211801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/20/2021] [Indexed: 06/13/2023]
Abstract
We report a measurement of the D^{0} and D^{+} lifetimes using D^{0}→K^{-}π^{+} and D^{+}→K^{-}π^{+}π^{+} decays reconstructed in e^{+}e^{-}→cc[over ¯] data recorded by the Belle II experiment at the SuperKEKB asymmetric-energy e^{+}e^{-} collider. The data, collected at center-of-mass energies at or near the ϒ(4S) resonance, correspond to an integrated luminosity of 72 fb^{-1}. The results, τ(D^{0})=410.5±1.1(stat)±0.8(syst) fs and τ(D^{+})=1030.4±4.7(stat)±3.1(syst) fs, are the most precise to date and are consistent with previous determinations.
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Search for B^{+}→K^{+}νν[over ¯] Decays Using an Inclusive Tagging Method at Belle II. PHYSICAL REVIEW LETTERS 2021; 127:181802. [PMID: 34767404 DOI: 10.1103/physrevlett.127.181802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 07/23/2021] [Accepted: 09/10/2021] [Indexed: 06/13/2023]
Abstract
A search for the flavor-changing neutral-current decay B^{+}→K^{+}νν[over ¯] is performed at the Belle II experiment at the SuperKEKB asymmetric energy electron-positron collider. The data sample corresponds to an integrated luminosity of 63 fb^{-1} collected at the ϒ(4S) resonance and a sample of 9 fb^{-1} collected at an energy 60 MeV below the resonance. Because the measurable decay signature involves only a single charged kaon, a novel measurement approach is used that exploits not only the properties of the B^{+}→K^{+}νν[over ¯] decay, but also the inclusive properties of the other B meson in the ϒ(4S)→BB[over ¯] event, to suppress the background from other B meson decays and light-quark pair production. This inclusive tagging approach offers a higher signal efficiency compared to previous searches. No significant signal is observed. An upper limit on the branching fraction of B^{+}→K^{+}νν[over ¯] of 4.1×10^{-5} is set at the 90% confidence level.
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Search for New Phenomena in Final States with Two Leptons and One or No b-Tagged Jets at sqrt[s]=13 TeV Using the ATLAS Detector. PHYSICAL REVIEW LETTERS 2021; 127:141801. [PMID: 34652194 DOI: 10.1103/physrevlett.127.141801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 07/30/2021] [Indexed: 06/13/2023]
Abstract
A search for new phenomena is presented in final states with two leptons and one or no b-tagged jets. The event selection requires the two leptons to have opposite charge, the same flavor (electrons or muons), and a large invariant mass. The analysis is based on the full run-2 proton-proton collision dataset recorded at a center-of-mass energy of sqrt[s]=13 TeV by the ATLAS experiment at the LHC, corresponding to an integrated luminosity of 139 fb^{-1}. No significant deviation from the expected background is observed in the data. Inspired by the B-meson decay anomalies, a four-fermion contact interaction between two quarks (b, s) and two leptons (ee or μμ) is used as a benchmark signal model, which is characterized by the energy scale and coupling, Λ and g_{*}, respectively. Contact interactions with Λ/g_{*} lower than 2.0 (2.4) TeV are excluded for electrons (muons) at the 95% confidence level, still far below the value that is favored by the B-meson decay anomalies. Model-independent limits are set as a function of the minimum dilepton invariant mass, which allow the results to be reinterpreted in various signal scenarios.
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Measurements of the Branching Fractions of the Semileptonic Decays Ξ_{c}^{0}→Ξ^{-}ℓ^{+}ν_{ℓ} and the Asymmetry Parameter of Ξ_{c}^{0}→Ξ^{-}π^{+}. PHYSICAL REVIEW LETTERS 2021; 127:121803. [PMID: 34597085 DOI: 10.1103/physrevlett.127.121803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 07/06/2021] [Accepted: 08/18/2021] [Indexed: 06/13/2023]
Abstract
Using data samples of 89.5 and 711 fb^{-1} recorded at energies of sqrt[s]=10.52 and 10.58 GeV, respectively, with the Belle detector at the KEKB e^{+}e^{-} collider, we report measurements of branching fractions of semileptonic decays Ξ_{c}^{0}→Ξ^{-}ℓ^{+}ν_{ℓ} (ℓ=e or μ) and the CP-asymmetry parameter of Ξ_{c}^{0}→Ξ^{-}π^{+} decay. The branching fractions are measured to be B(Ξ_{c}^{0}→Ξ^{-}e^{+}ν_{e})=(1.31±0.04±0.07±0.38)% and B(Ξ_{c}^{0}→Ξ^{-}μ^{+}ν_{μ})=(1.27±0.06±0.10±0.37)%, and the decay parameter α_{Ξπ} is measured to be 0.63±0.03±0.01 with much improved precision compared with the current world average. The corresponding ratio B(Ξ_{c}^{0}→Ξ^{-}e^{+}ν_{e})/B(Ξ_{c}^{0}→Ξ^{-}μ^{+}ν_{μ}) is 1.03±0.05±0.07, which is consistent with the expectation of lepton flavor universality. The first measured asymmetry parameter A_{CP}=(α_{Ξ^{-}π^{+}}+α_{Ξ[over ¯]^{+}π^{-}})/(α_{Ξ^{-}π^{+}}-α_{Ξ[over ¯]^{+}π^{-}})=0.024±0.052±0.014 is found to be consistent with zero. The first and the second uncertainties above are statistical and systematic, respectively, while the third ones arise due to the uncertainty of the Ξ_{c}^{0}→Ξ^{-}π^{+} branching fraction.
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Search for Displaced Leptons in sqrt[s]=13 TeV pp Collisions with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2021; 127:051802. [PMID: 34397238 DOI: 10.1103/physrevlett.127.051802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 03/03/2021] [Accepted: 06/11/2021] [Indexed: 06/13/2023]
Abstract
A search for charged leptons with large impact parameters using 139 fb^{-1} of sqrt[s]=13 TeV pp collision data from the ATLAS detector at the LHC is presented, addressing a long-standing gap in coverage of possible new physics signatures. Results are consistent with the background prediction. This search provides unique sensitivity to long-lived scalar supersymmetric lepton partners (sleptons). For lifetimes of 0.1 ns, selectron, smuon, and stau masses up to 720, 680, and 340 GeV, respectively, are excluded at 95% confidence level, drastically improving on the previous best limits from LEP.
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Longitudinal Flow Decorrelations in Xe+Xe Collisions at sqrt[s_{NN}]=5.44 TeV with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2021; 126:122301. [PMID: 33834811 DOI: 10.1103/physrevlett.126.122301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 06/16/2020] [Accepted: 02/12/2021] [Indexed: 06/12/2023]
Abstract
The first measurement of longitudinal decorrelations of harmonic flow amplitudes v_{n} for n=2-4 in Xe+Xe collisions at sqrt[s_{NN}]=5.44 TeV is obtained using 3 μb^{-1} of data with the ATLAS detector at the LHC. The decorrelation signal for v_{3} and v_{4} is found to be nearly independent of collision centrality and transverse momentum (p_{T}) requirements on final-state particles, but for v_{2} a strong centrality and p_{T} dependence is seen. When compared with the results from Pb+Pb collisions at sqrt[s_{NN}]=5.02 TeV, the longitudinal decorrelation signal in midcentral Xe+Xe collisions is found to be larger for v_{2}, but smaller for v_{3}. Current hydrodynamic models reproduce the ratios of the v_{n} measured in Xe+Xe collisions to those in Pb+Pb collisions but fail to describe the magnitudes and trends of the ratios of longitudinal flow decorrelations between Xe+Xe and Pb+Pb. The results on the system-size dependence provide new insights and an important lever arm to separate effects of the longitudinal structure of the initial state from other early and late time effects in heavy-ion collisions.
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Search for Dark Matter Produced in Association with a Dark Higgs Boson Decaying into W^{±}W^{∓} or ZZ in Fully Hadronic Final States from sqrt[s]=13 TeV pp Collisions Recorded with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2021; 126:121802. [PMID: 33834820 DOI: 10.1103/physrevlett.126.121802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 01/19/2021] [Indexed: 06/12/2023]
Abstract
Several extensions of the Standard Model predict the production of dark matter particles at the LHC. An uncharted signature of dark matter particles produced in association with VV=W^{±}W^{∓} or ZZ pairs from a decay of a dark Higgs boson s is searched for using 139 fb^{-1} of pp collisions recorded by the ATLAS detector at a center-of-mass energy of 13 TeV. The s→V(qq[over ¯])V(qq[over ¯]) decays are reconstructed with a novel technique aimed at resolving the dense topology from boosted VV pairs using jets in the calorimeter and tracking information. Dark Higgs scenarios with m_{s}>160 GeV are excluded.
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Medium-Induced Modification of Z-Tagged Charged Particle Yields in Pb+Pb Collisions at 5.02 TeV with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2021; 126:072301. [PMID: 33666476 DOI: 10.1103/physrevlett.126.072301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 11/03/2020] [Accepted: 01/08/2021] [Indexed: 06/12/2023]
Abstract
The yield of charged particles opposite to a Z boson with large transverse momentum (p_{T}) is measured in 260 pb^{-1} of pp and 1.7 nb^{-1} of Pb+Pb collision data at 5.02 TeV per nucleon pair recorded with the ATLAS detector at the Large Hadron Collider. The Z boson tag is used to select hard-scattered partons with specific kinematics, and to observe how their showers are modified as they propagate through the quark-gluon plasma created in Pb+Pb collisions. Compared with pp collisions, charged-particle yields in Pb+Pb collisions show significant modifications as a function of charged-particle p_{T} in a way that depends on event centrality and Z boson p_{T}. The data are compared with a variety of theoretical calculations and provide new information about the medium-induced energy loss of partons in a p_{T} regime difficult to measure through other channels.
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Observation and Measurement of Forward Proton Scattering in Association with Lepton Pairs Produced via the Photon Fusion Mechanism at ATLAS. PHYSICAL REVIEW LETTERS 2020; 125:261801. [PMID: 33449771 DOI: 10.1103/physrevlett.125.261801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 10/30/2020] [Accepted: 11/23/2020] [Indexed: 06/12/2023]
Abstract
The observation of forward proton scattering in association with lepton pairs (e^{+}e^{-}+p or μ^{+}μ^{-}+p) produced via photon fusion is presented. The scattered proton is detected by the ATLAS Forward Proton spectrometer, while the leptons are reconstructed by the central ATLAS detector. Proton-proton collision data recorded in 2017 at a center-of-mass energy of sqrt[s]=13 TeV are analyzed, corresponding to an integrated luminosity of 14.6 fb^{-1}. A total of 57 (123) candidates in the ee+p (μμ+p) final state are selected, allowing the background-only hypothesis to be rejected with a significance exceeding 5 standard deviations in each channel. Proton-tagging techniques are introduced for cross-section measurements in the fiducial detector acceptance, corresponding to σ_{ee+p}=11.0±2.6(stat)±1.2(syst)±0.3(lumi) and σ_{μμ+p}=7.2±1.6(stat)±0.9(syst)±0.2(lumi) fb in the dielectron and dimuon channel, respectively.
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Search for Heavy Resonances Decaying into a Photon and a Hadronically Decaying Higgs Boson in pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2020; 125:251802. [PMID: 33416363 DOI: 10.1103/physrevlett.125.251802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 11/05/2020] [Indexed: 06/12/2023]
Abstract
This Letter presents a search for the production of new heavy resonances decaying into a Higgs boson and a photon using proton-proton collision data at sqrt[s]=13 TeV collected by the ATLAS detector at the LHC. The data correspond to an integrated luminosity of 139 fb^{-1}. The analysis is performed by reconstructing hadronically decaying Higgs boson (H→bb[over ¯]) candidates as single large-radius jets. A novel algorithm using information about the jet constituents in the center-of-mass frame of the jet is implemented to identify the two b quarks in the single jet. No significant excess of events is observed above the expected background. Upper limits are set on the production cross-section times branching fraction for narrow spin-1 resonances decaying into a Higgs boson and a photon in the resonance mass range from 0.7 to 4 TeV, cross-section times branching fractions are excluded between 11.6 fb and 0.11 fb at a 95% confidence level.
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Gastrointestinal: Plastic stent-induced polyp-like lesion in the bile duct. J Gastroenterol Hepatol 2020; 35:2031. [PMID: 32498133 DOI: 10.1111/jgh.15092] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 05/07/2020] [Indexed: 12/09/2022]
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Search for Higgs Boson Decays into a Z Boson and a Light Hadronically Decaying Resonance Using 13 TeV pp Collision Data from the ATLAS Detector. PHYSICAL REVIEW LETTERS 2020; 125:221802. [PMID: 33315463 DOI: 10.1103/physrevlett.125.221802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 10/09/2020] [Indexed: 06/12/2023]
Abstract
A search for Higgs boson decays into a Z boson and a light resonance in two-lepton plus jet events is performed, using a pp collision dataset with an integrated luminosity of 139 fb^{-1} collected at sqrt[s]=13 TeV by the ATLAS experiment at the CERN LHC. The resonance considered is a light boson with a mass below 4 GeV from a possible extended scalar sector or a charmonium state. Multivariate discriminants are used for the event selection and for evaluating the mass of the light resonance. No excess of events above the expected background is found. Observed (expected) 95% confidence-level upper limits are set on the Higgs boson production cross section times branching fraction to a Z boson and the signal resonance, with values in the range 17-340 pb (16_{-5}^{+6}-320_{-90}^{+130} pb) for the different light spin-0 boson mass and branching fraction hypotheses, and with values of 110 and 100 pb (100_{-30}^{+40} and 100_{-30}^{+40} pb) for the η_{c} and J/ψ hypotheses, respectively.
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Association between insulin resistance and left ventricular diastolic dysfunction in non-diabetic general population. Eur Heart J 2020. [DOI: 10.1093/ehjci/ehaa946.3057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Background
Insulin resistance due to visceral fat accumulation plays a central role in the development of diabetic mellitus and subsequent cardiovascular disease. Abdominal obesity and diabetic mellitus are associated with the progression of left ventricular diastolic dysfunction which is the major structural abnormality in patients with heart failure. However, whether insulin resistance influences left ventricular diastolic dysfunction in non-diabetic subjects is unclear.
Purpose
In this study, we aimed to clarify the association between insulin resistance and left ventricular diastolic dysfunction in non-diabetic general population.
Methods
We examined 2,572 non-diabetic subjects with preserved left ventricular systolic function (ejection fraction ≥50%) and without a past history of diabetic mellitus, heart failure, coronary artery disease, atrial fibrillation, stroke, moderate to severe valvular disease, who underwent medical check-ups at the University of Tokyo Hospital from January 2009 to December 2018. Diabetes mellitus was defined as fasting glucose level ≥126 mg/dL or a subject's use of oral antidiabetic medications or insulin. We calculated the Homeostasis Model Assessment-Insulin Resistance (HOMA-IR) score [HOMA-IR = fasting glucose (mg/dL) × insulin (μU/mL) / 405], and defined insulin resistance as HOMA-IR ≥2.5. Left ventricular diastolic function was assessed by echocardiography, using tissue doppler analysis (E/E' ratio in septal and lateral). Visceral adiposity was assessed as visceral fat volume measured by computed tomography scanner.
Results
Mean age was 53.3±9.8 years, and 1,746 subjects (67.9%) were male. Overall, HOMA-IR was 1.1 on average, and HOMA-IR ≥2.5 was observed in 5.0% of study population. BMI and the prevalence of obesity were higher in subjects with HOMA-IR ≥2.5 than in those without. There was no significant difference in left ventricular ejection fraction between HOMA-IR ≥2.5 and ≤2.5. E/E' ratio in septal and lateral were higher in subjects with HOMA-IR ≥2.5 than in those without. Multivariable logistic regression analysis demonstrated that obesity and waist circumference, visceral fat volume were independently associated with HOMA-IR ≥2.5, however, age, hypertension, hypercholesterolemia were not. Further, multiple regression analysis including insulin resistance, age, male gender, obesity, hypertension, hypercholesterolemia, cigarette smoking and visceral fat volume, showed that insulin resistance was an independent determinant of increasing E/E' in both septal and lateral, whereas visceral fat volume was not (Figure 1).
Conclusion
The results of the present study suggest that insulin resistance due to visceral fat accumulation might be associated with the development of left ventricular diastolic dysfunction in non-diabetic general population without overt cardiovascular disease.
Figure 1
Funding Acknowledgement
Type of funding source: None
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Dijet Resonance Search with Weak Supervision Using sqrt[s]=13 TeV pp Collisions in the ATLAS Detector. PHYSICAL REVIEW LETTERS 2020; 125:131801. [PMID: 33034503 DOI: 10.1103/physrevlett.125.131801] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 07/12/2020] [Accepted: 08/04/2020] [Indexed: 05/11/2023]
Abstract
This Letter describes a search for narrowly resonant new physics using a machine-learning anomaly detection procedure that does not rely on signal simulations for developing the analysis selection. Weakly supervised learning is used to train classifiers directly on data to enhance potential signals. The targeted topology is dijet events and the features used for machine learning are the masses of the two jets. The resulting analysis is essentially a three-dimensional search A→BC, for m_{A}∼O(TeV), m_{B},m_{C}∼O(100 GeV) and B, C are reconstructed as large-radius jets, without paying a penalty associated with a large trials factor in the scan of the masses of the two jets. The full run 2 sqrt[s]=13 TeV pp collision dataset of 139 fb^{-1} recorded by the ATLAS detector at the Large Hadron Collider is used for the search. There is no significant evidence of a localized excess in the dijet invariant mass spectrum between 1.8 and 8.2 TeV. Cross-section limits for narrow-width A, B, and C particles vary with m_{A}, m_{B}, and m_{C}. For example, when m_{A}=3 TeV and m_{B}≳200 GeV, a production cross section between 1 and 5 fb is excluded at 95% confidence level, depending on m_{C}. For certain masses, these limits are up to 10 times more sensitive than those obtained by the inclusive dijet search. These results are complementary to the dedicated searches for the case that B and C are standard model bosons.
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Search for heavy neutral Higgs bosons produced in association with
b
-quarks and decaying into
b
-quarks at
s=13 TeV
with the ATLAS detector. Int J Clin Exp Med 2020. [DOI: 10.1103/physrevd.102.032004] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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CP Properties of Higgs Boson Interactions with Top Quarks in the tt[over ¯]H and tH Processes Using H→γγ with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2020; 125:061802. [PMID: 32845699 DOI: 10.1103/physrevlett.125.061802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 06/15/2020] [Indexed: 06/11/2023]
Abstract
A study of the charge conjugation and parity (CP) properties of the interaction between the Higgs boson and top quarks is presented. Higgs bosons are identified via the diphoton decay channel (H→γγ), and their production in association with a top quark pair (tt[over ¯]H) or single top quark (tH) is studied. The analysis uses 139 fb^{-1} of proton-proton collision data recorded at a center-of-mass energy of sqrt[s]=13 TeV with the ATLAS detector at the Large Hadron Collider. Assuming a CP-even coupling, the tt[over ¯]H process is observed with a significance of 5.2 standard deviations. The measured cross section times H→γγ branching ratio is 1.64_{-0.36}^{+0.38}(stat)_{-0.14}^{+0.17}(sys) fb, and the measured rate for tt[over ¯]H is 1.43_{-0.31}^{+0.33}(stat)_{-0.15}^{+0.21}(sys) times the Standard Model expectation. The tH production process is not observed and an upper limit on its rate of 12 times the Standard Model expectation is set. A CP-mixing angle greater (less) than 43 (-43)° is excluded at 95% confidence level.
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Search for Heavy Higgs Bosons Decaying into Two Tau Leptons with the ATLAS Detector Using pp Collisions at sqrt[s]=13 TeV. PHYSICAL REVIEW LETTERS 2020; 125:051801. [PMID: 32794886 DOI: 10.1103/physrevlett.125.051801] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 06/26/2020] [Indexed: 06/11/2023]
Abstract
A search for heavy neutral Higgs bosons is performed using the LHC Run 2 data, corresponding to an integrated luminosity of 139 fb^{-1} of proton-proton collisions at sqrt[s]=13 TeV recorded with the ATLAS detector. The search for heavy resonances is performed over the mass range 0.2-2.5 TeV for the τ^{+}τ^{-} decay with at least one τ-lepton decaying into final states with hadrons. The data are in good agreement with the background prediction of the standard model. In the M_{h}^{125} scenario of the minimal supersymmetric standard model, values of tanβ>8 and tanβ>21 are excluded at the 95% confidence level for neutral Higgs boson masses of 1.0 and 1.5 TeV, respectively, where tanβ is the ratio of the vacuum expectation values of the two Higgs doublets.
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Measurement of the Lund Jet Plane Using Charged Particles in 13 TeV Proton-Proton Collisions with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2020; 124:222002. [PMID: 32567910 DOI: 10.1103/physrevlett.124.222002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 05/06/2020] [Accepted: 05/13/2020] [Indexed: 06/11/2023]
Abstract
The prevalence of hadronic jets at the LHC requires that a deep understanding of jet formation and structure is achieved in order to reach the highest levels of experimental and theoretical precision. There have been many measurements of jet substructure at the LHC and previous colliders, but the targeted observables mix physical effects from various origins. Based on a recent proposal to factorize physical effects, this Letter presents a double-differential cross-section measurement of the Lund jet plane using 139 fb^{-1} of sqrt[s]=13 TeV proton-proton collision data collected with the ATLAS detector using jets with transverse momentum above 675 GeV. The measurement uses charged particles to achieve a fine angular resolution and is corrected for acceptance and detector effects. Several parton shower Monte Carlo models are compared with the data. No single model is found to be in agreement with the measured data across the entire plane.
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Measurement of Azimuthal Anisotropy of Muons from Charm and Bottom Hadrons in pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2020; 124:082301. [PMID: 32167369 DOI: 10.1103/physrevlett.124.082301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 11/29/2019] [Accepted: 01/22/2020] [Indexed: 06/10/2023]
Abstract
The elliptic flow of muons from the decay of charm and bottom hadrons is measured in pp collisions at sqrt[s]=13 TeV using a data sample with an integrated luminosity of 150 pb^{-1} recorded by the ATLAS detector at the LHC. The muons from heavy-flavor decay are separated from light-hadron decay muons using momentum imbalance between the tracking and muon spectrometers. The heavy-flavor decay muons are further separated into those from charm decay and those from bottom decay using the distance-of-closest-approach to the collision vertex. The measurement is performed for muons in the transverse momentum range 4-7 GeV and pseudorapidity range |η|<2.4. A significant nonzero elliptic anisotropy coefficient v_{2} is observed for muons from charm decays, while the v_{2} value for muons from bottom decays is consistent with zero within uncertainties.
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Search for Magnetic Monopoles and Stable High-Electric-Charge Objects in 13 Tev Proton-Proton Collisions with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2020; 124:031802. [PMID: 32031842 DOI: 10.1103/physrevlett.124.031802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 11/26/2019] [Indexed: 06/10/2023]
Abstract
A search for magnetic monopoles and high-electric-charge objects is presented using 34.4 fb^{-1} of 13 TeV pp collision data collected by the ATLAS detector at the LHC during 2015 and 2016. The considered signature is based upon high ionization in the transition radiation tracker of the inner detector associated with a pencil-shape energy deposit in the electromagnetic calorimeter. The data were collected by a dedicated trigger based on the tracker high-threshold hit capability. The results are interpreted in models of Drell-Yan pair production of stable particles with two spin hypotheses (0 and 1/2) and masses ranging from 200 to 4000 GeV. The search improves by approximately a factor of 5 the constraints on the direct production of magnetic monopoles carrying one or two Dirac magnetic charges and stable objects with electric charge in the range 20≤|z|≤60 and extends the charge range to 60<|z|≤100.
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Combined measurements of Higgs boson production and decay using up to
80 fb−1
of proton-proton collision data at
s=13 TeV
collected with the ATLAS experiment. Int J Clin Exp Med 2020. [DOI: 10.1103/physrevd.101.012002] [Citation(s) in RCA: 178] [Impact Index Per Article: 44.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Observation of Electroweak Production of a Same-Sign W Boson Pair in Association with Two Jets in pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2019; 123:161801. [PMID: 31702349 DOI: 10.1103/physrevlett.123.161801] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Indexed: 06/10/2023]
Abstract
This Letter presents the observation and measurement of electroweak production of a same-sign W boson pair in association with two jets using 36.1 fb^{-1} of proton-proton collision data recorded at a center-of-mass energy of sqrt[s]=13 TeV by the ATLAS detector at the Large Hadron Collider. The analysis is performed in the detector fiducial phase-space region, defined by the presence of two same-sign leptons, electron or muon, and at least two jets with a large invariant mass and rapidity difference. A total of 122 candidate events are observed for a background expectation of 69±7 events, corresponding to an observed signal significance of 6.5 standard deviations. The measured fiducial signal cross section is σ^{fid}=2.89_{-0.48}^{+0.51}(stat)_{-0.28}^{+0.29}(syst) fb.
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P827EXPLORE-J: Lipid management and 2-year long-term clinical outcome in Japanese patients with acute coronary syndrome. Eur Heart J 2019. [DOI: 10.1093/eurheartj/ehz747.0426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Background
The cardiovascular event rate in Japan is much lower than that in Western countries. However, the incidence of atherosclerotic CV disease and its burden are expected to increase in the Japanese society with rapid aging, westernization of lifestyles and metabolic derangement. An increase in patients with CAD has been remarkable in spite of various preventive measures. The positive linear correlation of LDL-C level with CAD incidence along with LDL-C lowering and CAD event reduction is established by large-scale studies in Western countries, but data in Japan are limited. EXPLORE-J, observational study, was conducted to gain insights into the relationship between LDL-C management and CV events in the Japanese ACS patients.
Purpose
The primary objective was to evaluate the status of post-ACS lipid management and CV events in Japan.
Method
ACS patients aged ≥20 years were enrolled and followed up for 2 years. The primary endpoint was the incidence proportion of major adverse cardiovascular events (MACE), including CV death (death associated with MI/stroke and other CV deaths), non-fatal ACS/stroke requiring hospitalization during the observation period. Other endpoints were medications and metabolic parameters. Additional stratified analyses of MACE incidence proportions by median LDL-C reduction category (above/below absolute or % reduction) from the first measurement after ACS to V1 (Day 1 + 14 days) was also conducted.
Result
Of the 2016 registered patients, 1944 were analyzed. The mean age and BMI were 66.0 years and 24.2 kg/m2, respectively. At 2-year follow up, the cumulative incidence proportion of MACE was 6.8%. The cumulative incidence proportions of CV death, non-fatal ACS and stroke were 0.7%, 4.5% and 1.7%, respectively. Statin, intensive statin, and ezetimibe were prescribed, respectively, to 93.6%, 8.2%, and 3.9% at V1, and 92.3%, 10.5%, and 11.6% at V5 (Day 730±30 days).
The mean LDL-C levels were 121.2, 99.4, 80.9, and 79.8 mg/dL at the first measurement after ACS, V1, V2 (Day 30±7 days) and V5, respectively. The proportions of patients who achieved LDL-C <70 and <100 mg/dL at V1 and V5 were 14.4% to 34.6% and 56.5% to 82.8%, respectively. The incidence rate of MACE was lower among patients with larger than median absolute reduction in LDL-C level than among those with smaller reduction (median −17.0 mg/dL; 5.5% vs 8.3%, p=0.0435). The same trend was observed in patients with higher LDL-C reduction rate (median −15.36%; 6.3% vs 7.6%, p=0.4302).
Kaplan-Meier estimates of MACE incidence
Conclusion
The results show the status of medical management and CV event rates in post-ACS Japanese patients. It also shows that half of the ACS patients did not achieve the recommended LDL-C levels of <70 mg/dL per guidelines, indicating the need to intensify lipid lowering therapy. To further characterize and quantify the patient population and the benefit of lipid management, we plan to conduct additional analyses with risk stratification of the population.
Acknowledgement/Funding
This study was sponsored by Sanofi and Regeneron Pharmaceuticals, Inc.
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