Search for emerging jets in pp collisions at SQUARE ROOT𝑠� = 13.6 TeV with the ATLAS experiment

Abstract

A search for emerging jets is presented using 51.8 fb-1 SQUARE ROOT of proton-proton collision data at s = 13.6 TeV, collected by the ATLAS experiment during 2022 and 2023. The search exploresa hypothetical dark sector featuring 'dark quarks' that are charged under a confining gaugegroup and couple to the standard model (SM) via a new mediator particle. These dark quarksundergo showering and hadronisation within the dark sector, forming long-lived dark mesonsthat decay back into SM particles. This results in jets that contain multiple displaced verticesknown as emerging jets. The analysis targets events with pairs of emerging jets, produced eitherthrough a vector mediator, Z', in the s-channel, or a scalar mediator, Φ, in the t-channel. Nosignificant excess over the SM background is observed. Assuming a dark pion proper decaylength between 5 mm and 50 mm, Z' mediator masses between 600 GeV and 2550 GeV areexcluded for quark and dark quark coupling values of 0.01 and 0.1, respectively. For a quarkdark-quark coupling of 0.1, Φ mediator masses between 600 GeV and 1375 GeV are excluded.These results represent the first direct search targeting emerging jet pair production via a Z'mediator, as well as the first study of emerging jet production mediated by a scalar particle exchanged in the t-channel.