HEP in Greek Classes

The HEP Inquiry learning resources created over the last four years by the European outreach projects are reviewed. The resources are mostly addressed to high school students and the purpose is to ignite their interest on science. In addition, at the University of Athens for the last four years we have been using the HYPATIA online event analysis tool as a lab course for fourth year undergraduate physics students, majoring in HEP. Each year 40–50 students highly appreciated the course, since they get a direct involvement in the actual toplevel research. Up to now, the course was limited to visual inspection of a few tens of ATLAS events. Recently we have enriched the course with additional analysis exercises, which involve large samples of events. The students, through a user friendly interface can analyze the samples (both signal and background ones) and optimize the cut selection in order to search for the Higgs decay H □ 4 leptons. Recently ATLAS released 1/fb of data, so starting now the students analyse real data

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