A New Look at the X Compositeness from its Lineshape
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arXiv
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| Autori principali: | , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2026
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| _version_ | 1866913118738710528 |
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| author | Carducci, A. Cianti, G. D'Annibali, P. Germani, D. Polosa, A. D. |
| author_facet | Carducci, A. Cianti, G. D'Annibali, P. Germani, D. Polosa, A. D. |
| contents | The existing analyses on the X(3872) lineshape are consistent with the hypothesis that it is a compact particle composed of four quarks. This conclusion follows from fitting available data with a Flatte' distribution 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 Dbar*, 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 Flatte' 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. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2605_12274 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | A New Look at the X Compositeness from its Lineshape Carducci, A. Cianti, G. D'Annibali, P. Germani, D. Polosa, A. D. High Energy Physics - Phenomenology The existing analyses on the X(3872) lineshape are consistent with the hypothesis that it is a compact particle composed of four quarks. This conclusion follows from fitting available data with a Flatte' distribution 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 Dbar*, 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 Flatte' 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. |
| title | A New Look at the X Compositeness from its Lineshape |
| topic | High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2605.12274 |