For the HL-LHC, ATLAS 1 will install a new all-silicon tracking system. The strip part will be comprised of five barrel layers and seven end cap disks on each side. The detectors will be connected to ...highly integrated, low mass front-end electronic hybrids with custom-made ASICs in 130nm CMOS technology. The hybrids will be flexible four layer copper polyimide constructions. They will be designed and populated at the universities involved, while the flexible PCBs will be produced in industry. This paper describes the evolution of hybrid designs for the barrel and end cap, discusses their electrical performance, and presents results from prototype modules made with the hybrids.
A
bstract
A search for new phenomena in events with two same-charge leptons or three leptons and jets identified as originating from
b
-quarks in a data sample of 36.1 fb
−1
of
pp
collisions at
s
=
...13
TeV recorded by the ATLAS detector at the Large Hadron Collider is reported. No significant excess is found and limits are set on vector-like quark, four-top-quark, and same-sign top-quark pair production. The observed (expected) 95% CL mass limits for a vector-like
T
- and
B
-quark singlet are
m
T
> 0.98 (0.99) TeV and
m
B
> 1.00 (1.01) TeV respectively. Limits on the production of the vector-like
T
5/3
-quark are also derived considering both pair and single production; in the former case the lower limit on the mass of the
T
5/3
-quark is (expected to be) 1.19 (1.21) TeV. The Standard Model four-top-quark production cross-section upper limit is (expected to be) 69 (29) fb. Constraints are also set on exotic four-top-quark production models. Finally, limits are set on same-sign top-quark pair production. The upper limit on
uu
→
tt
production is (expected to be) 89 (59) fb for a mediator mass of 1 TeV, and a dark-matter interpretation is also derived, excluding a mediator of 3 TeV with a dark-sector coupling of 1.0 and a coupling to ordinary matter above 0.31.
A
bstract
A search for charged Higgs bosons heavier than the top quark and decaying via
H
±
→
tb
is presented. The data analysed corresponds to 36.1 fb
−1
of
pp
collisions at
s
=
13
TeV and was ...recorded with the ATLAS detector at the LHC in 2015 and 2016. The production of a charged Higgs boson in association with a top quark and a bottom quark,
pp
→
tbH
±
, is explored in the mass range from
m
H
± = 200 to 2000 GeV using multi-jet final states with one or two electrons or muons. Events are categorised according to the multiplicity of jets and how likely these are to have originated from hadronisation of a bottom quark. Multivariate techniques are used to discriminate between signal and background events. No significant excess above the background-only hypothesis is observed and exclusion limits are derived for the production cross-section times branching ratio of a charged Higgs boson as a function of its mass, which range from 2.9 pb at
m
H
± = 200 GeV to 0.070 pb at
m
H
± = 2000 GeV. The results are interpreted in two benchmark scenarios of the Minimal Supersymmetric Standard Model.
A
bstract
This paper presents a search for direct electroweak gaugino or gluino pair production with a chargino nearly mass-degenerate with a stable neutralino. It is based on an integrated ...luminosity of 36.1 fb
−1
of
pp
collisions at
s
=
13
TeV collected by the ATLAS experiment at the LHC. The final state of interest is a disappearing track accompanied by at least one jet with high transverse momentum from initial-state radiation or by four jets from the gluino decay chain. The use of short track segments reconstructed from the innermost tracking layers significantly improves the sensitivity to short chargino lifetimes. The results are found to be consistent with Standard Model predictions. Exclusion limits are set at 95% confidence level on the mass of charginos and gluinos for different chargino lifetimes. For a pure wino with a lifetime of about 0.2 ns, chargino masses up to 460 GeV are excluded. For the strong production channel, gluino masses up to 1.65 TeV are excluded assuming a chargino mass of 460 GeV and lifetime of 0.2 ns.
The luminosity determination for the ATLAS detector at the LHC during Run 2 is presented, with
pp
collisions at a centre-of-mass energy
s
=
13
TeV. The absolute luminosity scale is determined using ...van der Meer beam separation scans during dedicated running periods in each year, and extrapolated to the physics data-taking regime using complementary measurements from several luminosity-sensitive detectors. The total uncertainties in the integrated luminosity for each individual year of data-taking range from 0.9% to 1.1%, and are partially correlated between years. After standard data-quality selections, the full Run 2
pp
data sample corresponds to an integrated luminosity of
140.1
±
1.2
fb
-
1
, i.e. an uncertainty of 0.83%. A dedicated sample of low-pileup data recorded in 2017–2018 for precision Standard Model physics measurements is analysed separately, and has an integrated luminosity of
338.1
±
3.1
pb
-
1
.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The inclusive top quark pair (
t
t
¯
) production cross-section
σ
t
t
¯
has been measured in proton–proton collisions at
s
=
13
TeV
, using 36.1 fb
-
1
of data collected in 2015–2016 by the ATLAS ...experiment at the LHC. Using events with an opposite-charge
e
μ
pair and
b
-tagged jets, the cross-section is measured to be:
σ
t
t
¯
=
826.4
±
3.6
(
stat
)
±
11.5
(
syst
)
±
15.7
(
lumi
)
±
1.9
(
beam
)
pb
,
where the uncertainties reflect the limited size of the data sample, experimental and theoretical systematic effects, the integrated luminosity, and the LHC beam energy, giving a total uncertainty of 2.4%. The result is consistent with theoretical QCD calculations at next-to-next-to-leading order. It is used to determine the top quark pole mass via the dependence of the predicted cross-section on
m
t
pole
, giving
m
t
pole
=
173
.
1
-
2.1
+
2.0
GeV
. It is also combined with measurements at
s
=
7
TeV
and
s
=
8
TeV
to derive ratios and double ratios of
t
t
¯
and
Z
cross-sections at different energies. The same event sample is used to measure absolute and normalised differential cross-sections as functions of single-lepton and dilepton kinematic variables, and the results are compared with predictions from various Monte Carlo event generators.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A search for new heavy particles that decay into top-quark pairs is performed using data collected from proton–proton collisions at a centre-of-mass energy of 13
TeV
by the ATLAS detector at the ...Large Hadron Collider. The integrated luminosity of the data sample is 36.1 fb
-
1
. Events consistent with top-quark pair production are selected by requiring a single isolated charged lepton, missing transverse momentum and jet activity compatible with a hadronic top-quark decay. Jets identified as likely to contain
b
-hadrons are required to reduce the background from other Standard Model processes. The invariant mass spectrum of the candidate top-quark pairs is examined for local excesses above the background expectation. No significant deviations from the Standard Model predictions are found. Exclusion limits are set on the production cross-section times branching ratio for hypothetical
Z
′
bosons, Kaluza–Kein gluons and Kaluza–Klein gravitons that decay into top-quark pairs.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
Background
Galectin-3 is a β-galactoside-binding lectin that has been described to be overexpressed in inflammation, atherosclerosis, and in myocardial fibrosis. In COVID-19, galectin-3 has ...been proposed as an important regulator of the inflammatory response and fibrosis processes. The role of galectin-3 as a platelet activator and thrombosis enhancer has been also recently described. However, the role of galectin-3 in the thrombotic risk in COVID-19 hasn't been studied extensively.
Methods
Patients with moderate to severe COVID-19 were included in the study. Hospitalized patients with acute respiratory diseases without COVID-19 were examined as controls. We compared the levels of galectin-3, soluble ST2, tissue factor and tissue factor activity (TFa) as well as several other markers of increased thrombogenicity in both groups. The correlations between galectin-3 and coagulation as well as inflammation markers were assessed. The SOFA score was used as a marker for the clinical outcome.
Results
93 patients were included into the study of which 56 were SARS-CoV-2 positive (COV+) and 37 were SARS-CoV-2 negative controls (COV−). Galectin-3 levels were higher in the COV+ group (median 7.10 ng/ml IQR 4.61–9.81 vs. 5.47 ng/ml 3.63–6.66 p=0.016) as well as the TFa (median 334.48 pM 115.19–632.58 vs. 134.02 pM 86.92–206.66) and the ST2 levels (median 5.49 ng/ml 2.40–9.28 vs. 2.19 ng/ml 0.66–3.91 p<0.001). We also observed a positive correlation between galectin-3 and IL-6 (r=0.559, p<0.001), ST2 (r=0.332, p=0.005), SOFA score (r=0.441, p=0.003), von Willebrand factor (r=0.401, p<0.001), plasminogen (r=0.361, p=0.001), antithrombin (r=0.453, p<0.001), and D-dimer (r=0.377, p=0.001).
Conclusion
In patients with acute respiratory diseases, especially with COVID-19, galectin-3 is a marker for increased hypercoagulability and worse clinical outcome. Galactin-3 might be a useful therapeutic target for patients with COVID-19.
Funding Acknowledgement
Type of funding sources: None.
Abstract
Background
Hemostasis is dysregulated in patients with moderate-to-severe coronavirus disease 2019 (COVID-19). However, patients with respiratory diseases other than COVID-19 can also show ...disturbed coagulation reactions during the acute inflammatory process. Parameters of coagulation and platelet function are here compared between patients with upper respiratory infections with and without COVID-19 and are related to the clinical outcome.
Methods
Hospitalized patients with acute respiratory symptoms and with severe acute respiratory syndrome coronavirus 2 (SARS-CoV2)-positive (COVpos) and SARS-CoV2-negative (COVneg) status were included. We assessed several parameters of coagulation and fibrinolysis as well as adenosine diphosphate (ADP)-, thrombin receptor activator peptide 6 (TRAP)-, and arachidonic acid (AA)-induced platelet reactivity by impedance aggregometry, as well as leukocyte subtype spectrum and platelet-leukocyte aggregates by flow cytometry and inflammatory cytokines by cytometric bead array. The SOFA score was assessed as marker of the clinical outcome.
Results
87 patients were included in the study of which 50 were COVpos and 37 were COVneg. Von Willebrand factor was significantly higher in COVID positive patients compared to the control group (4456,4 mU/ml 2701,4; 9067,0 vs. 2528,0 mU/ml 1301,2; 3693,8, p<0,001). COVID-positive patients exhibited also more tissue plasminogen activator in the circulating blood than COVID-negative patients with an respiratory infection (11,4 mU/ml 7,2; 24,6 vs. 7,3 mU/ml 4,9; 10,5, p=0,001). ADP, TRAP-, and AA-induced platelet reactivity was significantly higher in COVpos than in COVneg patients. The SOFA score was higher in COVpos than in COVneg patients and again higher in deceased COVpos patients than in surviving COVpos. The SOFA score correlated significantly with parameters of coagulation and platelet function. A larger percentage of classical and intermediate monocytes, and of CD4pos T cells (TH) aggregated with platelets in COVpos than in COVneg patients. Interleukin (IL)-1 receptor antagonist (RA) and IL-6 levels were higher in COVpos than in COVneg patients and again higher in deceased COVpos patients than in surviving COVpos. IL-1RA and IL-6 levels correlated with the SOFA score in COVpos but not in COVneg patients, indicating a COVID-19-specific mechanism.
Conclusion
In moderate-to-severe COVID-19, but not in other respiratory diseases, disease severity was associated with parameters of coagulation and platelet function. Dysregulated coagulation and platelet hyperreactivity were associated to a worse clinical outcome in patients with COVID-19, pointing to the importance of antithrombotic therapy for reducing disease severity.
Funding Acknowledgement
Type of funding sources: None.
PDF
