The effects of related experiments

The effects of the experiment itself upon the obtained results and, especially, the influence of a large number of experiments are extensively discussed in the literature. We show that the important factor that stands at the basis of these effects is that the involved experiments are related and not independent and detached from each other. This relationship takes, as shown here, different forms for different situations and is found in entirely different physical regimes such as the quantum and classical ones.Comment: 27 pages, 6 figures, 1 table. One figure removed. Some former text has been rewritten in compact and clearer way. Also the title change

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV

The Effects of Glacial Cover on Riverine Silicon Isotope Compositions in Chilean Patagonia

Proglacial rivers have been shown to have distinctive silicon (Si) isotope compositions, providing new insights into the mechanisms controlling Si cycling in the subglacial environment and suggesting terrestrial Si isotope exports may have varied between glacial and interglacial periods. However, Si isotope data are currently limited to a small number of glacial systems in the northern hemisphere, and it is unclear how compositions might vary across a spectrum of glacial influence. Using Chilean Patagonia as a unique natural laboratory, we present Si isotope compositions of 0.45 µm filtered (fSi), 0.02 µm filtered (DSi) and reactive amorphous (ASi) fractions from 40 river catchments with variable glacial cover and explore the key controls on Si cycling. The 0.45 µm filtered glacier-fed river samples displayed isotopically light compositions and a positive linear correlation with upstream glacial cover. This relationship was controlled by the inclusion of an isotopically light colloidal-nanoparticulate (0.02 -- 0.45 µm) silicate phase that was only present in glacier-fed rivers and dominated Si budgets in these catchments. This phase was predominately composed of feldspars and its lability in seawater is uncertain, representing a significant unknown in resolving glacial Si isotope exports from this region. When the colloidal-nanoparticulates were removed from solution by ultra-filtration, the resultant DSi isotope compositions of glacier-fed catchments were not isotopically distinct from some non-glacial rivers and exhibited no clear relationship with glacial cover. The colloidal-nanoparticulate concentration of other weathering-sensitive elements (Li, Mg, Ba, Sr) also showed a linear relationship with glacial cover, suggesting that their isotopic compositions could be affected in a similar manner. These findings highlight the benefit of size-fractionated sampling and the need for more research to understand the lability of colloidal-nanoparticulate species, especially in glacier-fed rivers. Finally, we explore the controls on river ASi isotope compositions and show how including these reactive particulate phases is critical to quantifying terrestrial Si isotope budgets, both in Patagonia and other global regions

Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

The influence of glacial cover on riverine silicon and iron exports in Chilean Patagonia

Glaciated environments have been highlighted as important sources of bioavailable nutrients, with inputs of glacial meltwater potentially influencing productivity in downstream ecosystems. However, it is currently unclear how riverine nutrient concentrations vary across a spectrum of glacial cover, making it challenging to accurately predict how terrestrial fluxes will change with continued glacial retreat. Using 40 rivers in Chilean Patagonia as a unique natural laboratory, we investigate how glacial cover affects riverine Si and Fe concentrations, and infer how exports of these bioessential nutrients may change in the future. Dissolved Si (as silicic acid) and soluble Fe (0.45 mu m) phases of both Si and Fe, which are not typically accounted for in terrestrial nutrient budgets but can dominate riverine exports. Dissolved Si and soluble Fe yield estimates showed no trend with glacial cover, suggesting no significant change in total exports with continued glacial retreat. However, yields of colloidal-nanoparticulate and reactive sediment-bound Si and Fe were an order of magnitude greater in highly glaciated catchments and showed significant positive correlations with glacial cover. As such, regional-scale exports of these phases are likely to decrease as glacial cover disappears across Chilean Patagonia, with potential implications for downstream ecosystems

A Lagrangian scheme for the solution of nonlinear diffusion equations using moving simplex meshes

A Lagrangian numerical scheme for solving nonlinear degenerate Fokker{Planck equations in space dimensions d>2 is presented. It applies to a large class of nonlinear diffusion equations, whose dynamics are driven by internal energies and given external potentials, e.g. the porous medium equation and the fast diffusion equation. The key ingredient in our approach is the gradient ow structure of the dynamics. For discretization of the Lagrangian map, we use a finite subspace of linear maps in space and a variational form of the implicit Euler method in time. Thanks to that time discretisation, the fully discrete solution inherits energy estimates from the original gradient ow, and these lead to weak compactness of the trajectories in the continuous limit. Consistency is analyzed in the planar situation, d = 2. A variety of numerical experiments for the porous medium equation indicates that the scheme is well-adapted to track the growth of the solution's support

Ricci curvature of finite Markov chains via convexity of the entropy

We study a new notion of Ricci curvature that applies to Markov chains on discrete spaces. This notion relies on geodesic convexity of the entropy and is analogous to the one introduced by Lott, Sturm, and Villani for geodesic measure spaces. In order to apply to the discrete setting, the role of the Wasserstein metric is taken over by a different metric, having the property that continuous time Markov chains are gradient flows of the entropy. Using this notion of Ricci curvature we prove discrete analogues of fundamental results by Bakry--Emery and Otto--Villani. Furthermore we show that Ricci curvature bounds are preserved under tensorisation. As a special case we obtain the sharp Ricci curvature lower bound for the discrete hypercube.Comment: 39 pages, to appear in Arch. Ration. Mech. Ana

Seasonal changes in dissolved organic matter composition in a Patagonian fjord affected by glacier melt inputs

Biogeochemical processes in fjords are likely affected by changes in surrounding glacier cover but very little is known about how meltwater directly influences dissolved organic matter (DOM) in fjords. Moreover, the data available are restricted to a handful of northern hemisphere sites. Here we analyze seasonal and spatial variation in dissolved organic carbon (DOC) concentration and DOM composition (spectrofluorescence, ultrahigh resolution mass spectrometry) in Baker-Martinez Fjord, Chilean Patagonia (48°S), to infer the impacts of rapid regional deglaciation on fjord DOM. We show that surface layer DOC concentrations do not vary significantly between seasons, but DOM composition is sensitive to differences in riverine inputs. In summer, higher protein-like fluorescence reflects increased glacial meltwater inputs, whilst molecular level data show weaker influence from marine DOM due to more intense stratification. We postulate that the shifting seasonal balance of riverine and marine waters affects the supply of biolabile peptides and organic nitrogen cycling in the surface layer. Trends in DOM composition with increasing salinity are consistent with patterns in estuaries (i.e. preferential removal of aromatic compounds and increasing relative contribution of unsaturated and heteroatom-rich DOM from marine sources). Preliminary estimates also suggest that at least 10 of the annual organic carbon stock in this fjord is supplied by the four largest, glacially fed rivers and that these inputs are dominated by dissolved (84) over particulate organic carbon. Riverine DOC may therefore be an important carbon subsidy to bacterial communities in the inner fjord. The overall findings highlight the biogeochemical sensitivity of a Patagonian fjord to changes in glacier melt input, which likely has relevance for other glaciated fjords in a warming climate

Search for W\u27→tb decays in the hadronic final state using ppcollisions at √s=13TeVwith the ATLAS detector

A search for W\u27-boson production in the W\u27→t¯b→q¯q\u27b¯b decay channel is presented using 36.1fb−1of 13TeV proton–proton collision data collected by the ATLAS detector at the Large Hadron Collider in 2015 and 2016. The search is interpreted in terms of both a left-handed and a right-handed chiral W\u27 boson within the mass range 1–5 TeV. Identification of the hadronically decaying top quark is performed using jet substructure tagging techniques based on a shower deconstruction algorithm. No significant deviation from the Standard Model prediction is observed and the results are expressed as upper limits on the W\u27→t¯bproduction cross-section times branching ratio as a function of the W\u27-boson mass. These limits exclude W\u27 bosons with right-handed couplings with masses below 3.0TeV and W\u27 bosons with left-handed couplings with masses below 2.9TeV, at the 95% confidence level