UC Irvine

Properties of the underlying-event in pp interactions are investigated primarily via the strange hadrons KS0$$K_{S}^{0}$$, Λ$$\Lambda $$ and Λ¯$$\bar{\Lambda }$$, as reconstructed using the ATLAS detector at the LHC in minimum-bias pp collision data at s=13$$\sqrt{s} = 13$$ TeV. The hadrons are reconstructed via the identification of the displaced two-particle vertices corresponding to the decay modes , Λ→π-p$$\Lambda \rightarrow \pi ^-p$$ and Λ¯→π+p¯$$\bar{\Lambda }\rightarrow \pi ^+\bar{p}$$. These are used in the construction of underlying-event observables in azimuthal regions computed relative to the leading charged-particle jet in the event. None of the hadronisation and underlying-event physics models considered can describe the data over the full kinematic range considered. Events with a leading charged-particle jet in the range of 10