# V Workshop on Particle Correlations and Femtoscopy

14-17 October 2009
CERN
Europe/Zurich timezone

## Particle-antiparticle back-to-back correlation measurement in $\sqrt{s_{NN}}=200$ GeV Au+Au collisions

15 Oct 2009, 16:50
30m
TH Auditorium (CERN)

### TH Auditorium

#### CERN

Talk Squeezed States and Particle-Antiparticle Back-to-Back Correlation

### Speaker

Marton Nagy (MTA KFKI RMKI)

### Description

for the PHENIX Collaboration The collision of energetic nuclei forms a hot and dense partonic matter. Determining the nature of the phase transition associated with the production of the observed hadrons is an important task. Experimental data on direction-dependent correlation length (HBT radii) studies seem to exclude the possibility of a strong first order phase transition in $\sqrt{s_{NN}}=200$ GeV Au+Au collisions, while lattice QCD calculations favorize a cross-over type of hadron formation. A novel type of correlations, hypothesized in the late 1980's and fully highlighted in the last decade, is sensitive to the medium effects on the produced hadrons. This type of quantum mechanical correlations, called back-to-back correlations, or squeezed back-to-back correlations, was predicted among particle-antiparticle pairs, both $\pi^+\pi^-$, $K^+K^-$, or $p\bar{p}$ pairs, if their masses are modified by the medium due to hadronic interactions or chiral dynamics. Observation and exploring the properties of such correlation effect would thus provide a unique insight into the freeze-out dynamics of the hot and dense partonic matter created in heavy ion collisions. The experimental details and the latest status of the PHENIX measurement of this type of particle-antiparticle back-to-back correlations will be presented.

### Primary author

Marton Nagy (MTA KFKI RMKI)

 Slides