Λ-Λ hyperons: the road to estimate the production cross-section in proton-proton collisions
by
AlbaNova B4:1059 - Instrumenteringsfysik/Admin
AlbaNova Main Building
Abstract
In this study, we analyse the Λ-Λ hyperon channel in proton-proton scattering,
pp 7→ ΛΛ + K+K+, Λ 7→ p + π−, with a proton beam energy of 4.5
GeV using the High Acceptance Di-Electron Spectrometer (HADES) at GSI.
The purpose of the study presented here is to measure the production crosssection
for the Λ-Λ channel. We develop a multi-stage analysis strategy to
first determine the acceptance-reconstruction efficiency for the Λ-Λ channel
from simulations produced according to phase space. The analysis of data
is perforned for three different event selections: inclusive (pp 7→ ΛΛ + X),
semi-exclusive (pp 7→ ΛΛ + K+ + X) and the fully exclusive. For each selection,
the data is represented by a two-dimensional histogram, where the
axes correspond to the p+π− invariant mass of the respective Λ candidate.
The Λ-Λ signal is determined using a Statistical sideband analysis (SSB)
and a Linear least squares (LLS) fit. The inclusive selection provides the
most significant Λ-Λ signal. Cross-section values corresponding to the two
analyses are calculated as weighted average of the result of the three selections.
The production cross-section for Λ-Λ in pp collisions at
√s = 3.46 GeV is measured to be 59 ± 27 nb (one standard deviation uncertainity).
