2024 Articles

Underlying-event studies with strange hadrons in 𝑝𝑝 collisions at √𝑠 = 13 TeV with the ATLAS detector

Al Khoury, Konie

Abstract
Properties of the underlying-event in 𝑝𝑝 interactions are investigated primarily via the strange hadrons Kᴼ_s, 𝚲 and 𝚲̄, as reconstructed using the ATLAS detector at the LHC in minimum-bias 𝑝𝑝 collision data at √𝑠 = 13 TeV. The hadrons are reconstructed via the identification of the displaced two-particle vertices corresponding to the decay modes, 𝚲 → 𝜋 - 𝜌 and 𝚲̄ → 𝜋 + 𝜌̄. 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 < 𝑝𝑇 ≤ 40 GeV are studied using the number of prompt charged particles in the transverse region. The ratio 𝑁 ( 𝚲 + 𝚲̄ ) / 𝑁 (Kᴼ_s) as a function of the number of such charged particles varies only slightly over this range. This disagrees with the expectations of some of the considered Monte Carlo models.