Precise determination of the properties of X(3872) and of its isovector partner W_c1.

Authors

Teng Ji, Xiang-Kun Dong, Feng-Kun Guo, Christoph Hanhart, Ulf-G Meißner

Published in

Science bulletin. Aug 03, 2026. Epub Aug 03, 2026.

Abstract

We perform a simultaneous fit to BESIII data on e⁺e^-→γ(D⁰D‾⁰π⁰/J/ψπ⁺π^-) and LHCb data on B⁺→K⁺(J/ψπ⁺π^-) to precisely determine the properties of the X(3872), with full consideration of three-body effects from D^∗→Dπ decay, respecting both analyticity and unitarity. The X(3872) is determined to be a quasi-bound state with a significance of 2.7σ, representing the most precise determination to date. Its pole is located at -160_-74⁺⁵⁷-125_-38⁺²³ikeV, relative to the nominal D⁰D‾^*0 threshold. Moreover, we confirm the presence of an isovector partner state, W_c1. It is found as a virtual state at 3.1±0.7+1.3_-0.6^+1.9iMeV relative to the D⁺D^*- threshold on an unphysical Riemann sheet, strongly supporting a molecular nature of both X(3872) and W_c1. As a highly nontrivial prediction, we show that the W_c1 leads to nontrivial lineshapes around 3.88 GeV in B⁰→K⁰X(3872)→K⁰D⁰D¯⁰π⁰ and K⁰J/ψπ⁺π^--thus the scheme presented here can be tested further by improved measurements.

PMID:
42608273
Bibliographic data and abstract were imported from PubMed on 18 Aug 2026.

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