Measurements of aerosol microphysical and chemical properties in the central Arctic atmosphere during MOSAiC.

The Arctic environment is transforming rapidly due to climate change. Aerosols' abundance and physicochemical characteristics play a crucial, yet uncertain, role in these changes due to their influence on the surface energy budget through direct interaction with solar radiation and indirectly via cloud formation. Importantly, Arctic aerosol properties are also changing in response to climate change.

The Marginal Ice Zone as a dominant source region of atmospheric mercury during central Arctic summertime.

Atmospheric gaseous elemental mercury (GEM) concentrations in the Arctic exhibit a clear summertime maximum, while the origin of this peak is still a matter of debate in the community. Based on summertime observations during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition and a modeling approach, we further investigate the sources of atmospheric Hg in the central Arctic. Simulations with a generalized additive model (GAM) show that long-range transport of anthropogenic and terrestrial Hg from lower latitudes is a minor contribution (~2%), and more than 50% of the explained GEM variability is caused by oceanic evasion.

Profile observations of the Arctic atmospheric boundary layer with the BELUGA tethered balloon during MOSAiC.

During the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition, the Balloon-bornE moduLar Utility for profilinG the lower Atmosphere (BELUGA) was deployed from an ice floe drifting in the Fram Strait from 29 June to 27 July 2020. The BELUGA observations aimed to characterize the cloudy Arctic atmospheric boundary layer above the sea ice using a modular setup of five instrument packages. The in situ measurements included atmospheric thermodynamic and dynamic state parameters (air temperature, humidity, pressure, and three-dimensional wind), broadband solar and terrestrial irradiance, aerosol particle microphysical properties, and cloud particle images.

Continuous observations of the surface energy budget and meteorology over the Arctic sea ice during MOSAiC.

The Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) was a yearlong expedition supported by the icebreaker R/V Polarstern, following the Transpolar Drift from October 2019 to October 2020. The campaign documented an annual cycle of physical, biological, and chemical processes impacting the atmosphere-ice-ocean system. Of central importance were measurements of the thermodynamic and dynamic evolution of the sea ice.

Year-round trace gas measurements in the central Arctic during the MOSAiC expedition.

Despite the key role of the Arctic in the global Earth system, year-round in-situ atmospheric composition observations within the Arctic are sparse and mostly rely on measurements at ground-based coastal stations. Measurements of a suite of in-situ trace gases were performed in the central Arctic during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition. These observations give a comprehensive picture of year-round near-surface atmospheric abundances of key greenhouse and trace gases, i.

Data from the MOSAiC Arctic Ocean drift experiment.

The Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) is a multinational interdisciplinary endeavor of a large earth system sciences community.

A central arctic extreme aerosol event triggered by a warm air-mass intrusion.

Frequency and intensity of warm and moist air-mass intrusions into the Arctic have increased over the past decades and have been related to sea ice melt. During our year-long expedition in the remote central Arctic Ocean, a record-breaking increase in temperature, moisture and downwelling-longwave radiation was observed in mid-April 2020, during an air-mass intrusion carrying air pollutants from northern Eurasia. The two-day intrusion, caused drastic changes in the aerosol size distribution, chemical composition and particle hygroscopicity.

Annual cycle observations of aerosols capable of ice formation in central Arctic clouds.

The Arctic is warming faster than anywhere else on Earth, prompting glacial melt, permafrost thaw, and sea ice decline. These severe consequences induce feedbacks that contribute to amplified warming, affecting weather and climate globally. Aerosols and clouds play a critical role in regulating radiation reaching the Arctic surface.

Polar Ocean Observations: A Critical Gap in the Observing System and Its Effect on Environmental Predictions From Hours to a Season.

There is a growing need for operational oceanographic predictions in both the Arctic and Antarctic polar regions. In the former, this is driven by a declining ice cover accompanied by an increase in maritime traffic and exploitation of marine resources. Oceanographic predictions in the Antarctic are also important, both to support Antarctic operations and also to help elucidate processes governing sea ice and ice shelf stability.

Erratum to: Measurement of the boson polarisation in events from collisions at in the lepton + jets channel with ATLAS.

[This corrects the article DOI: 10.1140/epjc/s10052-017-4819-4.].

Measurement of the Soft-Drop Jet Mass in pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector.

Jet substructure observables have significantly extended the search program for physics beyond the standard model at the Large Hadron Collider. The state-of-the-art tools have been motivated by theoretical calculations, but there has never been a direct comparison between data and calculations of jet substructure observables that are accurate beyond leading-logarithm approximation. Such observables are significant not only for probing the collinear regime of QCD that is largely unexplored at a hadron collider, but also for improving the understanding of jet substructure properties that are used in many studies at the Large Hadron Collider.

Search for a Structure in the B_{s}^{0}π^{±} Invariant Mass Spectrum with the ATLAS Experiment.

A search for the narrow structure, X(5568), reported by the D0 Collaboration in the decay sequence X→B_{s}^{0}π^{±}, B_{s}^{0}→J/ψϕ, is presented. The analysis is based on a data sample recorded with the ATLAS detector at the LHC corresponding to 4.9  fb^{-1} of pp collisions at 7 TeV and 19.

Myelodysplasia and Mast Cell Leukemia with t(9;22).

Introduction: Mast cell leukemia (MCL) is a rare variant of systemic mastocytosis. Most cases of mast cell leukemia do not have cytogenics performed. Furthermore, there is no consistent chromosomal abnormality identified in MCL.

Direct top-quark decay width measurement in the lepton+jets channel at with the ATLAS experiment.

This paper presents a direct measurement of the decay width of the top quark using events in the lepton+jets final state. The data sample was collected by the ATLAS detector at the LHC in proton-proton collisions at a centre-of-mass energy of 8 TeV and corresponds to an integrated luminosity of 20.2 fb .

Search for new phenomena in high-mass final states with a photon and a jet from collisions at = 13 TeV with the ATLAS detector.

A search is performed for new phenomena in events having a photon with high transverse momentum and a jet collected in of proton-proton collisions at a centre-of-mass energy of = 13 TeV recorded with the ATLAS detector at the Large Hadron Collider. The invariant mass distribution of the leading photon and jet is examined to look for the resonant production of new particles or the presence of new high-mass states beyond the Standard Model. No significant deviation from the background-only hypothesis is observed and cross-section limits for generic Gaussian-shaped resonances are extracted.

Search for heavy resonances decaying into in the final state in collisions at with the ATLAS detector.

A search for neutral heavy resonances is performed in the decay channel using collision data corresponding to an integrated luminosity of , collected at a centre-of-mass energy of 13 by the ATLAS detector at the Large Hadron Collider. No evidence of such heavy resonances is found. In the search for production via the quark-antiquark annihilation or gluon-gluon fusion process, upper limits on as a function of the resonance mass are obtained in the mass range between 200 and up to 5 for various benchmark models: a Higgs-like scalar in different width scenarios, a two-Higgs-doublet model, a heavy vector triplet model, and a warped extra dimensions model.

Search for doubly charged Higgs boson production in multi-lepton final states with the ATLAS detector using proton-proton collisions at .

A search for doubly charged Higgs bosons with pairs of prompt, isolated, highly energetic leptons with the same electric charge is presented. The search uses a proton-proton collision data sample at a centre-of-mass energy of 13 TeV corresponding to 36.1 of integrated luminosity recorded in 2015 and 2016 by the ATLAS detector at the LHC.

Measurement of the -boson mass in pp collisions at with the ATLAS detector.

A measurement of the mass of the boson is presented based on proton-proton collision data recorded in 2011 at a centre-of-mass energy of 7 TeV with the ATLAS detector at the LHC, and corresponding to of integrated luminosity. The selected data sample consists of candidates in the channel and candidates in the channel. The -boson mass is obtained from template fits to the reconstructed distributions of the charged lepton transverse momentum and of the boson transverse mass in the electron and muon decay channels, yielding where the first uncertainty is statistical, the second corresponds to the experimental systematic uncertainty, and the third to the physics-modelling systematic uncertainty.

Search for dark matter produced in association with bottom or top quarks in TeV collisions with the ATLAS detector.

A search for weakly interacting massive dark-matter particles produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and missing transverse momentum are considered. The analysis uses of proton-proton collision data recorded by the ATLAS experiment at  TeV in 2015 and 2016.

Measurement of polarisation in decays in proton-proton collisions at TeV with the ATLAS detector.

This paper presents a measurement of the polarisation of leptons produced in decays which is performed with a dataset of proton-proton collisions at TeV, corresponding to an integrated luminosity of 20.2 fb recorded with the ATLAS detector at the LHC in 2012. The decays are reconstructed from a hadronically decaying lepton with a single charged particle in the final state, accompanied by a lepton that decays leptonically.

Measurement of longitudinal flow decorrelations in Pb+Pb collisions at and 5.02 TeV with the ATLAS detector.

Measurements of longitudinal flow correlations are presented for charged particles in the pseudorapidity range using 7 and 470 of Pb+Pb collisions at and 5.02 TeV, respectively, recorded by the ATLAS detector at the LHC. It is found that the correlation between the harmonic flow coefficients measured in two separated intervals does not factorise into the product of single-particle coefficients, and this breaking of factorisation, or flow decorrelation, increases linearly with the separation between the intervals.

Measurement of quarkonium production in proton-lead and proton-proton collisions at with the ATLAS detector.

The modification of the production of , , and ( ) in +Pb collisions with respect to their production in collisions has been studied. The +Pb and datasets used in this paper correspond to integrated luminosities of and respectively, collected in 2013 and 2015 by the ATLAS detector at the LHC, both at a centre-of-mass energy per nucleon pair of 5.02 TeV.

Search for the direct production of charginos and neutralinos in final states with tau leptons in collisions with the ATLAS detector.

A search for the direct production of charginos and neutralinos in final states with at least two hadronically decaying tau leptons is presented. The analysis uses a dataset of collisions corresponding to an integrated luminosity of 36.1 fb , recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 13 TeV.