CLASS and OSNAP report for JC238

The aim of this expedition was to recover and redeploy all moorings in the OSNAP array and to obtain a CTD section of hydrographic, nutrients, dissolved oxygen and dissolved organic carbon observations along the OSNAP section. The specific measurement objectives of the cruise were: 1. Recover and redeploy 4 existing mooring along the Ellett Array (EB1, WB1, WB2, RH ADCP) and 3 existing moorings in the Iceland Basin (IB5, IB4, IB3) 2. Deploy new drift-free pressure recorder (Sonardyne Fetch AZA) at EB1. 3. Conduct CTD stations and capture water samples for oxygen, total carbon, alkalinity and nutrients analysis. Data from the CTD stations was provided in near-real time (<12 hours) to the UK Met. Office to be assimilated into their short-range ocean forecast models: global 0.25 degree, North Atlantic 1/12th degree and AMM15 (European NW Shelf, ~ 1.5 km). 4. Recover and redeploy a sediment trap mooring on the Darwin Sea Mounds (DMLTM) as part of the UK Marine Protected Area habitat monitoring programme. 5. Deploy three BGC-Argo floats to maintain the UK contribution to the global ARGO network. 6. Using ship-based instrumentation to measure underway meteorology, sea-surface temperature and salinity, ocean currents from the surface to ~400m depth and waterdepth using a Kongsberg multibeam echo sounding system

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