OKC BSM meeting (in A5:1041 and on zoom)

Thursday 19 Jan 2023, 10:00 → 11:05 Europe/Stockholm

AlbaNova A5:1041 - CoPS grupprum (AlbaNova Main Building)

Christian Ohm (KTH Royal Institute of Technology), Timothy Linden (Stockholm University)

Those who are at AlbaNova can come to A5:1041, but there will also be a zoom connection:

https://kth-se.zoom.us/j/104167778?pwd=b3EzTWJKTkJibmVnNFZLYllUNklPUT09 (room 104 167 778, password 737501)

10:00 → 10:05 Brief intro

Speakers: Christian Ohm (KTH Royal Institute of Technology), Timothy Linden (Stockholm University)

10:05 → 10:45 Search for dark matter and top quark pairs with ATLAS

Talk by Xuanhong Lou (SU).

Abstract: This paper presents a statistical combination of searches targeting final states with two top quarks and invisible particles, characterised by the presence of zero, one or two leptons, at least one jet originating from a $b$-quark and missing transverse momentum. The analyses are searches for phenomena beyond the Standard Model consistent with the direct production of dark matter in $pp$ collisions at the LHC, using 139 fb$^{-\text{1}}$ of data collected with the ATLAS detector at a centre-of-mass energy of 13 TeV. The results are interpreted in terms of simplified dark matter models with a spin-0 scalar or pseudoscalar mediator particle. In addition, the results are interpreted in terms of upper limits on the Higgs boson invisible branching ratio, where the Higgs boson is produced according to the Standard Model in association with a pair of top quarks. For scalar (pseudoscalar) dark matter models, with all couplings set to unity, the statistical combination extends the mass range excluded by the best of the individual channels by 50 (25) GeV, excluding mediator masses up to 370 GeV. In addition, the statistical combination improves the expected coupling exclusion reach by 14% (24%), assuming a scalar (pseudoscalar) mediator mass of 10 GeV. An upper limit on the Higgs boson invisible branching ratio of 0.38 ($\text{0.30}^{+\text{0.13}}_{-\text{0.09}}$) is observed (expected) at 95% confidence level.

Speaker: Xuanhong Lou (Stockholm University)

TTMET_230119.pdf