https://doi.org/10.1140/epjc/s10052-025-14838-y
Regular Article - Theoretical Physics
Correlation functions for 
and 
1
Instituto de Física, Universidade de São Paulo, 05389-970, São Paulo, Brazil
2
Departamento de Física Teórica and IFIC, Centro Mixto Universidad de Valencia-CSIC, Institutos de Investigación de Paterna, 46071, Valencia, Spain
3
Instituto de Física, Universidade Federal da Bahia, 40170-115, Salvador, Bahia, Brazil
4
Universidade Federal de São Paulo, 01302-907, São Paulo, Brazil
5
Guangxi Key Laboratory of Nuclear Physics and Technology, Guangxi Normal University, 541004, Guilin, China
a
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Received:
15
August
2025
Accepted:
21
September
2025
Published online:
12
October
2025
Abstract
We study the interaction of the 
and 
systems from the perspective that the 
and 
states are molecular states of 
and 
respectively. We use an improved version of the fixed center approximation to the Faddeev equations which fulfills exact elastic unitarity at the threshold of the systems. We predict the existence of resonant states below threshold and also determine the scattering length, effective range and correlation functions of these systems, showing that the results contain important information to test the assumed molecular nature of the two 
states.
© The Author(s) 2025
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