Sifting out the neutral and charged components of X(3872) from a spin observable

2025/11/13 by Wang, Ke, Wang, Yu-Fei, Liu, Bo-Chao +1
#FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph)

paper · doi:10.48550/arxiv.2511.09981

Abstract

In this work, we propose a new method to detect the composition of the X(3872) state. Based on a widely accepted interpretation that X(3872) is a weakly bound S-wave molecule of the D^*0 D⁰ (neutral) and D^*+ D^- (charged) configurations, the process X(3872) → D^*0 D⁰ is described by one-loop triangle diagrams with the corresponding components as intermediate particles, and with the parameters constrained by the experimental branching ratio. Unlike the mild behavior of the neutral component, the charged component manifests itself as a distinct structure near the D^*+ D^- threshold at 3.880 GeV, in the M_D^*0 D⁰ invariant mass distribution of the spin density matrix element ρ^{D^*}₀₀. Hence the line shape of ρ^{D^*}₀₀ near this structure depends sensitively on the proportions of the two configurations. We propose high-precision measurements of this matrix element by future BESIII and Belle experiments to elucidate how a molecular X(3872) state is composed.

Related

• Nature of X(3872) from recent BESIII data: Considering the universal feature of an S-wave threshold resonance
• Charmless decays of the spin-2 partner of X(3872)
• Production of the X(3872) state via the B⁰ → K^{∗ 0} X(3872) decay
• Light hadronic decays of spin-0 partner of X(3872)
• Precise determination of the properties of X(3872) and of its isovector partner W_c1