# DPF2015

4-8 August 2015
America/Detroit timezone

## Measurement of Correlation of Lambda Pairs with the ATLAS Detector

5 Aug 2015, 17:40
20m
Room 4 (Michigan League)

QCD Experiment

### Speaker

Hok Chuen Cheng (University of Michigan (US))

### Description

We report here the first observation of a direct spin correlation between pairs of like-type and unlike-type $\Lambda$ hyperons produced in inclusive processes at the LHC. The analysis is based on hyperon pairs collected at the ATLAS experiment from pp collisions at a center-of-mass energy of 7 TeV in 2010. A depletion of like-type events when compared to unlike-type events is observed for $Q<3$ GeV and is known to be the effect of the Fermi-Dirac statistics between identical fermions. The correlation parameter of the decay angles for decay $\Lambda \rightarrow p \pi^-$ ($\bar{\Lambda} \rightarrow \bar{p} \pi^+$) is extracted for data as a function of $Q$ using a data-driven reference sample in which uncorrelated hyperon pairs are selected from different events in the same data sample. No spin correlation has been observed for unlike-type events, while deviation from zero is observed for like-type events in the same region where depletion of differential cross-section occurs.
Oral or Poster Presentation Oral

### Primary author

Hok Chuen Cheng (University of Michigan (US))