New Paper

New ATLAS group paper

December 9, 2021

Collider Physics Group

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.

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Latest Group News

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 Paper

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.

New Member

New Member in the ATLAS group

January 12, 2022

Adrià Berrocal has just joined the ATLAS group as a PhD student.