The Many Uses of Matā on Rapa Nui

Obsidian tools with a stem or tang attached to a blade and known as matā have been recovered from a broad range of archaeological contexts on Rapa Nui. Their highly variable morphology suggests that this class of artifact had multiple, but too few analyses of their use-wear have been conducted to be confident about the relationships between form and use. A sample of 22 matā from sealed archaeological deposits in a cave on the southern coast of Rapa Nui and ranging in age from ca. A.D. 1300–1800 were analyzed using high power magnification. The patterns of use-wear scarring, striations, polishes, and residues demonstrate that the tools were all hafted and were used in a broad range of activities including fish processing and the manufacture and/or decoration of wooden, bone, and shell artifacts. The results demonstrate the importance of additional comprehensive usewear and residue studies for understanding the multiple roles of matā within ancient Rapa Nui society

Mid-Holocene Social Interaction in Melanesia: New Evidence from Hammer-Dressed Obsidian Stemmed Tools

The widespread distribution in Papua New Guinea of obsidian stemmed tools dated to the mid-Holocene has led scholars to postulate the existence of large interaction spheres. A newly reported artifact from Biak Island, West Papua provides the stimulus for reconsidering the role of this tool type in regional social interaction. The tool was hammer-dressed, a technique unknown for obsidian flaked tools elsewhere in the world and only rarely applied to obsidian artifacts in Melanesia. This new find closely resembles hammer-dressed obsidian stemmed tools from Garua Island, Papua New Guinea, but these are characterized by LA/ICPMS, PIXE-PGME, and INAA to the local Baki and Kutau-Bao obsidian sources in New Britain, Papua New Guinea, whereas the Biak tool is sourced to outcrops on Lou Island in Manus Province, Papua New Guinea. Hypotheses for functional, symbolic, and social roles of hammer-dressing are explored and evaluated on the basis of replication experiments and use-wear analyses. We argue that the complex and exceptionally rare technologies used for manufacturing hammer-dressed stemmed tools and applied to obsidian acquired from two widely separated obsidian sources substantially add to previous evidence for wide-scale social interaction during the mid-Holocene. The existence of these social networks might also have provided a mechanism for the rapid, extensive spread of innovations like Austronesian languages or Lapita pottery

Archaeobotany in Australia and New Guinea: practice, potential and prospects

Archaeobotany is the study of plant remains from archaeological contexts. Despite Australasian research being at the forefront of several methodological innovations over the last three decades, archaebotany is now a relatively peripheral concern to most archaeological projects in Australia and New Guinea. In this paper, many practicing archaeobotanists working in these regions argue for a more central role for archaeobotany in standard archaeological practice. An overview of archaeobotanical techniques and applications is presented, the potential for archaeobotany to address key historical research questions is indicated, and initiatives designed to promote archaeobotany and improve current practices are outlined

Archaeobotany in Australia and New Guinea: practice, potential and prospects

Archaeobotany is the study of plant remains from archaeological contexts. Despite Australasian research being at the forefront of several methodological innovations over the last three decades, archaebotany is now a relatively peripheral concern to most archaeological projects in Australia and New Guinea. In this paper, many practicing archaeobotanists working in these regions argue for a more central role for archaeobotany in standard archaeological practice. An overview of archaeobotanical techniques and applications is presented, the potential for archaeobotany to address key historical research questions is indicated, and initiatives designed to promote archaeobotany and improve current practices are outlined

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 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

Search for direct stau production in events with two hadronic tau-leptons in root s=13 TeV pp collisions with the ATLAS detector

A search for the direct production of the supersymmetric partners ofτ-leptons (staus) in final stateswith two hadronically decayingτ-leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of139fb−1, recorded with the ATLAS detector at the LargeHadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected StandardModel background is observed. Limits are derived in scenarios of direct production of stau pairs with eachstau decaying into the stable lightest neutralino and oneτ-lepton in simplified models where the two staumass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidencelevel for a massless lightest neutralino

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

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Measurements of inclusive and differential fiducial cross-sections of tt production with additional heavy-flavour jets in proton-proton collisions at √ s= 13 TeV with the ATLAS detector

This paper presents measurements of tt production in association with additional b-jets in pp collisions at the LHC at a centre-of-mass energy of 13 TeV. The data were recorded with the ATLAS detector and correspond to an integrated luminosity of 36.1 fb−1. Fiducial cross-section measurements are performed in the dilepton and lepton-plus-jets tt decay channels. Results are presented at particle level in the form of inclusive cross-sections of tt final states with three and four b-jets as well as differential cross-sections as a function of global event properties and properties of b-jet pairs. The measured inclusive fiducial cross-sections generally exceed the ttbb predictions from various next-to-leading-order matrix element calculations matched to a parton shower but are compatible within the total uncertainties. The experimental uncertainties are smaller than the uncertainties in the predictions. Comparisons of state-of-the-art theoretical predictions with the differential measurements are shown and good agreement with data is found for most of them