A New Look at the X Compositeness from its Lineshape
Abstract
Available data on the X(3872) lineshape have been fitted with a Flattè parametrization derived from an effective Lagrangian in which X, D, and D* are all elementary fields. A molecular X, i.e., a deuteron-like bound state of D and D̅*, must instead be described by an effective theory where the X field is initially absent or introduced as an auxiliary, unphysical, field, yielding a lineshape parametrization that differs significantly from the Flattè one. We demonstrate, in the analogous theory of nucleons with an auxiliary deuteron field, that this parametrization gives a fully consistent description of np→deuteron→ np scattering data, and motivate applying the same method to the X lineshape. The analysis proposed here is novel and has not previously been carried out on the available data.
Related
- Compositeness of near-threshold exotic hadrons in systems with Coulomb and short-range interactions
- Resonant Di-Higgs Searches in bb̅τ+τ- at HL-LHC: Supersymmetry versus Compositeness Benchmarks
- Compositeness and decay properties of the flavor partner of D*s0(2317)
- On Compositeness of Ds0*(2317) and its decay to Dsπ0
- Probing neutrino compositeness with invisible and displaced signals
BibTeX
@misc{carducci2026look,
title = {{A New Look at the X Compositeness from its Lineshape}},
author = {A. Carducci and G. Cianti and P. D'Annibali and D. Germani and A. D. Polosa},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2605.12274},
eprint = {2605.12274},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.12274},
}
RIS
TY - UNPB
TI - A New Look at the X Compositeness from its Lineshape
AU - A. Carducci
AU - G. Cianti
AU - P. D'Annibali
AU - D. Germani
AU - A. D. Polosa
PY - 2026
DA - 2026/10/16
PB - arXiv
DO - 10.48550/arxiv.2605.12274
UR - https://arxiv.org/abs/2605.12274
AB - Available data on the X(3872) lineshape have been fitted with a Flattè parametrization derived from an effective Lagrangian in which X, D, and D^* are all elementary fields. A molecular X, i.e., a deuteron-like bound state of D and D̅^*, must instead be described by an effective theory where the X field is initially absent or introduced as an auxiliary, unphysical, field, yielding a lineshape parametrization that differs significantly from the Flattè one. We demonstrate, in the analogous theory of nucleons with an auxiliary deuteron field, that this parametrization gives a fully consistent description of np→deuteron→ np scattering data, and motivate applying the same method to the X lineshape. The analysis proposed here is novel and has not previously been carried out on the available data.
ER -