Effective Contact Theory for Exotic Loosely Bound States in Strongly Interacting Expanding Matter
Abstract
Short-distance correlations generate universal relations that can be independent of microscopic details. Tan's contact is a prominent example, connecting close pairs, high-momentum constituents, and bound-state formation across atomic, condensed-matter, and nuclear systems. Whether an analogous universality governs the nonequilibrium freeze-out of relativistic QCD matter is an open question. We develop an effective contact theory that relates the production of loosely bound states to continuum two-particle correlations in heavy-ion collisions. The construction replaces the hard relative-momentum cutoff of conventional coalescence by a regulated Bethe--Peierls kernel: freeze-out localization fixes its momentum scale, while the composite yield fixes its contact residue. Bound and continuum observables then become projections of a common two-particle density matrix rather than independent phenomena. Coulomb-bound Kμ atoms provide an ideal realization because their atomic, production, and source scales are widely separated. A contact-theory analysis of STAR dΛ correlations supplies a first bound--continuum consistency test and demonstrates how inferred near-threshold parameters can depend on the finite expanding source. The framework establishes a general strategy for relating coalescence, correlations, and exotic bound states in strongly interacting expanding matter.
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BibTeX
@misc{wang2026effective,
title = {{Effective Contact Theory for Exotic Loosely Bound States in Strongly Interacting Expanding Matter}},
author = {Xiaofeng Wang and Zebo Tang and Zhangbu Xu and Chi Yang and Wangmei Zha},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.38579},
eprint = {2609.38579},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.38579},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Effective Contact Theory for Exotic Loosely Bound States in Strongly Interacting Expanding Matter
AU - Xiaofeng Wang
AU - Zebo Tang
AU - Zhangbu Xu
AU - Chi Yang
AU - Wangmei Zha
PY - 2026
DA - 2026/09/29
PB - arXiv
DO - 10.48550/arxiv.2609.38579
UR - https://arxiv.org/abs/2609.38579
AB - Short-distance correlations generate universal relations that can be independent of microscopic details. Tan's contact is a prominent example, connecting close pairs, high-momentum constituents, and bound-state formation across atomic, condensed-matter, and nuclear systems. Whether an analogous universality governs the nonequilibrium freeze-out of relativistic QCD matter is an open question. We develop an effective contact theory that relates the production of loosely bound states to continuum two-particle correlations in heavy-ion collisions. The construction replaces the hard relative-momentum cutoff of conventional coalescence by a regulated Bethe--Peierls kernel: freeze-out localization fixes its momentum scale, while the composite yield fixes its contact residue. Bound and continuum observables then become projections of a common two-particle density matrix rather than independent phenomena. Coulomb-bound Kμ atoms provide an ideal realization because their atomic, production, and source scales are widely separated. A contact-theory analysis of STAR dΛ correlations supplies a first bound--continuum consistency test and demonstrates how inferred near-threshold parameters can depend on the finite expanding source. The framework establishes a general strategy for relating coalescence, correlations, and exotic bound states in strongly interacting expanding matter.
ER -