479 research outputs found
Nonspecific Immunoglobulin Replacement in Lung Transplantation Recipients With Hypogammaglobulinemia
No full textInternational audienceBACKGROUND: After lung transplantation (LT), immunoglobulin (Ig) G plasma concentrations<6 g/L are common and correlate with an increased risk of chronic lung allograft dysfunction (CLAD) and a poorer survival.METHODS: We conducted an open substitution intervention with nonspecific intravenous Ig (IVIg), in all patients with IgG plasma less than 6 g/L post-LT in 54 of 84 consecutive recipients since 1998 who survived more than 3 months. Pre-LT and post-LT events were retrospectively analyzed
Search for heavy Higgs bosons with flavour-violating couplings in multi-lepton plus -jets final states in collisions at 13 TeV with the ATLAS detector
No full textA search for new heavy scalars with flavour-violating decays in final states
with multiple leptons and -tagged jets is presented. The results are
interpreted in terms of a general two-Higgs-doublet model involving an
additional scalar with couplings to the top-quark and the three up-type quarks
(, , and ). The targeted signals lead to final
states with either a same-sign top-quark pair, three top-quarks, or four
top-quarks. The search is based on a data sample of proton-proton collisions at
TeV recorded with the ATLAS detector during Run 2 of the Large
Hadron Collider, corresponding to an integrated luminosity of 139f b.
Events are categorised depending on the multiplicity of light charged leptons
(electrons or muons), total lepton charge, and a deep-neural-network-based
categorisation to enhance the purity of each of the signals. Masses of an
additional scalar boson between GeV with couplings
, , and are excluded at 95%
confidence level. Additional interpretations are provided in models of
-parity violating supersymmetry, motivated by the recent flavour and
anomalies.Comment: 66 pages in total, author list starting page 49, 17 figures, 9
tables, published by JHEP. All figures including auxiliary figures are
available at
http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HDBS-2020-03
Measurements of differential cross sections of Higgs boson production through gluon fusion in the final state at TeV with the ATLAS detector
No full textHiggs boson production via gluon-gluon fusion is measured in the decay channel. The dataset utilized corresponds to an
integrated luminosity of 139 fb collected by the ATLAS detector from
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.Comment: 59 pages in total, author list starting page 42, 22 figures, 6
tables, published in EPJC. All figures including auxiliary figures are
available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2018-49
ATLAS flavour-tagging algorithms for the LHC Run 2 collision dataset
No full textThe flavour-tagging algorithms developed by the ATLAS Collaboration and used
to analyse its dataset of TeV collisions from Run 2 of the
Large Hadron Collider are presented. These new tagging algorithms are based on
recurrent and deep neural networks, and their performance is evaluated in
simulated collision events. These developments yield considerable improvements
over previous jet-flavour identification strategies. At the 77% -jet
identification efficiency operating point, light-jet (charm-jet) rejection
factors of 170 (5) are achieved in a sample of simulated Standard Model
events; similarly, at a -jet identification efficiency of 30%, a
light-jet (-jet) rejection factor of 70 (9) is obtained.Comment: 52 pages in total, author list starting page 35, 19 figures, 2
tables, published in EPJC. All figures including auxiliary figures are
available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/FTAG-2019-07
Search for periodic signals in the dielectron and diphoton invariant mass spectra using 139 fb of collisions at 13 TeV with the ATLAS detector
No full textA search for physics beyond the Standard Model inducing periodic signals in
the dielectron and diphoton invariant mass spectra is presented using 139
fb of TeV collision data collected by the ATLAS
experiment at the LHC. Novel search techniques based on continuous wavelet
transforms are used to infer the frequency of periodic signals from the
invariant mass spectra and neural network classifiers are used to enhance the
sensitivity to periodic resonances. In the absence of a signal, exclusion
limits are placed at the 95\% confidence level in the two-dimensional parameter
space of the clockwork gravity model. Model-independent searches for deviations
from the background-only hypothesis are also performed.Comment: 47 pages in total, author list starting page 30, 10 figures, 2
tables, published as JHEP 10 (2023) 079. All figures including auxiliary
figures are available at
http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/EXOT-2019-4
Measurement of the Effective Lifetime with the ATLAS Detector
No full textThis paper reports the first ATLAS measurement of the
effective lifetime. The measurement is based on the data collected in
2015-2016, amounting to 26.3 fb of 13 TeV LHC proton-proton collisions.
The proper decay-time distribution of background-subtracted signal
candidates is fit with simulated signal templates parameterised as a function
of the effective lifetime, with statistical uncertainties extracted
through a Neyman construction. The resulting effective measurement of the
lifetime is and it is found to be consistent with the
Standard Model.Comment: 32 pages in total, author list starting page 14, 4 figures and 1
table. All figures/tables (including auxiliary ones), are available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/BPHY-2020-07
Search for pairs of muons with small displacements in collisions at TeV with the ATLAS detector
No full textA search new phenomena giving rise to pairs of opposite electrically charged
muons with impact parameters in the millimetre range is presented, using 139
fb of TeV collision data from the ATLAS detector at
the LHC. The search targets the gap in coverage between existing searches
targeting final states with leptons with large displacement and prompt leptons.
No significant excess over the background expectation is observed and exclusion
limits are set on the mass of long-lived scalar supersymmetric muon-partners
(smuons) with much lower lifetimes than previously targeted by displaced muon
searches. Smuon lifetimes down to 1 ps are excluded for a smuon mass of 100
GeV, and smuon masses up to 520 GeV are excluded for a proper lifetime of 10
ps, at 95% confidence level. Finally, model-independent limits are set on the
contribution from new phenomena to the signal-region yields.Comment: 32 pages in total, author list starting page 15, 4 figures, 2 tables,
published in Phys.Lett. B. All figures including auxiliary figures are
available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/SUSY-2020-09
Combination of searches for invisible decays of the Higgs boson using 139 fb of proton-proton collision data at TeV collected with the ATLAS experiment
No full textMany 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 of proton-proton collisions at a centre-of-mass energy of
TeV at the LHC. In combination with the results at
TeV and 8 TeV, 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.Comment: 35 pages in total, author list starting page 18, 4 figures, 1 table,
published to Physics Letters B (Phys. Lett. B 842 (2023) 137963). All figures
including auxiliary figures are available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2021-0
Search for Majorana neutrinos in same-sign scattering events from collisions at TeV
No full textA search for Majorana neutrinos in same-sign scattering events is
presented. The analysis uses TeV proton-proton collision data
with an integrated luminosity of 140 fb recorded during 2015-2018 by the
ATLAS detector at the Large Hadron Collider. The analysis targets final states
including exactly two same-sign muons and at least two hadronic jets well
separated in rapidity. The modelling of the main backgrounds, from Standard
Model same-sign scattering and production, is constrained with data
in dedicated signal-depleted control regions. The distribution of the
transverse momentum of the second-hardest muon is used to search for signals
originating from a heavy Majorana neutrino with a mass between 50 GeV and 20
TeV. No significant excess is observed over the background expectation. The
results are interpreted in a benchmark scenario of the Phenomenological Type-I
Seesaw model. In addition, the sensitivity to the Weinberg operator is
investigated. Upper limits at the 95% confidence level are placed on the
squared muon-neutrino-heavy-neutrino mass-mixing matrix element as a function of the heavy Majorana neutrino's mass , and on
the effective Majorana neutrino mass .Comment: 37 pages in total, author list starting page 19, 3 figures, 1 table.
All figures including auxiliary figures are available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/EXOT-2020-06
Measurement of the Higgs boson mass with decays in 140 fb of TeV collisions with the ATLAS detector
No full textThe mass of the Higgs boson is measured in the decay
channel, exploiting the high resolution of the invariant mass of photon pairs
reconstructed from the decays of Higgs bosons produced in proton-proton
collisions at a centre-of-mass energy TeV. The dataset was
collected between 2015 and 2018 by the ATLAS detector at the Large Hadron
Collider, and corresponds to an integrated luminosity of 140 fb. The
measured value of the Higgs boson mass is GeV and is based on an improved energy scale calibration
for photons, whose impact on the measurement is about four times smaller than
in the previous publication. A combination with the corresponding measurement
using 7 and 8 TeV collision ATLAS data results in a Higgs boson mass
measurement of
GeV. With an uncertainty of 1.1 per mille, this is currently the most precise
measurement of the mass of the Higgs boson from a single decay channel.Comment: 36 pages in total, author list starting page 19, 3 figures, 2 tables,
published in Phys. Lett. B. All figures and tables including auxiliary
figures and tables are available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2019-16
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