New ATLAS group paper
December 9, 2021Collider Physics Group
“Measurement of the tttt production cross section in pp collisions at sqrt(s)=13 TeV with the ATLAS detector" has been published in JHEP 11 (2021) 118.
This paper presents a measurement of the four-top-quark production cross section in final states with a single lepton or an opposite-sign lepton pair in association with multiple jets using the full Run 2 dataset collected with the ATLAS detector. With four top quarks produced per event, this is a very rare Standard Model process with a predicted cross section of only 12 fb, and thus is very sensitive to beyond-the-SM contributions.
A sophisticated event categorization and multivariate technique is used to discriminate signal from background events. The result of this analysis is combined with a previous measurement in multilepton final states. The combined cross section is measured to be a factor of two higher than the SM prediction, although compatible with it within 2.0 standard deviations. The corresponding observed (expected) signal significance is 4.7 (2.6) standard deviations over the background-only prediction.
Members of the IFAE-ATLAS team (Aurelio Juste, Nicola Orlando, and Anil Sonay) have played a leading role in this publication, from designing the analysis strategy to the final multivariate technique and statistical analysis employed.
In the Media
Martine Bosman interviewed on the La Mira online magazine
January 12, 2022
Martine Bosman has been interviewed in the La Mira online Magazine
New ATLAS pixel group paper
January 12, 2022
“Characterization of Irradiated Boron, Carbon-Enriched and Gallium Si-on-Si Wafer Low Gain Avalanche Detectors” by L. Castillo García and others, has been published in a special issue of Instruments journal dedicated to Timing Detectors.