The Compact X and Z and their Invisible Molecular Partners

Fuente: arXiv
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Main Authors: Carducci, A., Grinstein, B., Germani, D., Polosa, A. D.
Format: Preprint
Published: 2025
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author Carducci, A.
Grinstein, B.
Germani, D.
Polosa, A. D.
author_facet Carducci, A.
Grinstein, B.
Germani, D.
Polosa, A. D.
contents We propose a model explaining the strong isospin violations observed in X(3872) decays. The X is assumed to be a compact isosinglet tetraquark and its charged partners to form an isotriplet, together with an additional neutral state mixing with the isosinglet. The isotriplet results from the loose binding of open charm mesons and, in isolation, has strongly suppressed production rates. However, its neutral component can still mix with the isosinglet and induce the large isospin violations observed. The compact-isosinglet/molecular-isotriplet pattern appears reversed when the Z(3900) resonances are considered. The Z particles observed correspond to a compact isotriplet and there is no evidence of a neutral isosinglet Z. We show that no isospin violation in the Z decays is expected.
format Preprint
id arxiv_https___arxiv_org_abs_2512_21538
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Compact X and Z and their Invisible Molecular Partners
Carducci, A.
Grinstein, B.
Germani, D.
Polosa, A. D.
High Energy Physics - Phenomenology
We propose a model explaining the strong isospin violations observed in X(3872) decays. The X is assumed to be a compact isosinglet tetraquark and its charged partners to form an isotriplet, together with an additional neutral state mixing with the isosinglet. The isotriplet results from the loose binding of open charm mesons and, in isolation, has strongly suppressed production rates. However, its neutral component can still mix with the isosinglet and induce the large isospin violations observed. The compact-isosinglet/molecular-isotriplet pattern appears reversed when the Z(3900) resonances are considered. The Z particles observed correspond to a compact isotriplet and there is no evidence of a neutral isosinglet Z. We show that no isospin violation in the Z decays is expected.
title The Compact X and Z and their Invisible Molecular Partners
topic High Energy Physics - Phenomenology
url https://arxiv.org/abs/2512.21538