Molecular components in $\mathbf{D_{s0}^{\ast}(2317)}$ and $\mathbf{D_{s1}(2460)}$ mesons

TL;DR

This paper investigates the nature of the narrow $D_{s0}^{ ext{*}}(2317)$ and $D_{s1}(2460)$ mesons, showing that their masses are lowered by coupling to meson-meson thresholds within a constrained nonrelativistic quark model, aligning with experimental observations.

Contribution

The study introduces a nonrelativistic quark model incorporating meson-meson degrees of freedom, highlighting the importance of threshold couplings in explaining meson masses and properties beyond naive quark models.

Findings

Coupling to $DK$ and $D^{*}K$ thresholds lowers meson masses.

Model reproduces the $D_{s1}(2536)$ decay properties.

Provides probabilities of different Fock components in mesons.

Abstract

Different experiments have confirmed that the $D_{s0}^{\ast}(2317)$ and $D_{s1}(2460)$ mesons are very narrow states located, respectively, below the $DK$ and $D^{\ast}K$ thresholds. This is markedly in contrast with the expectations of naive quark models and heavy quark symmetry. We address the mass shifts of the $c\bar{s}$ ground states with quantum numbers $J^{P}=0^{+}$ ($D_{s0}^{\ast}(2317)$) and $J^{P}=1^{+}$ ($D_{s1}(2460)$) using a nonrelativistic constituent quark model in which quark-antiquark and meson-meson degrees of freedom are incorporated. The quark model has been applied to a wide range of hadronic observables and thus the model parameters are completely constrained. We observe that the coupling of the $0^{+}$ $(1^{+})$ meson sector to the $DK$ $(D^{\ast}K)$ threshold is a key feature in lowering the masses of the corresponding $D_{s0}^{\ast}(2317)$ and $D_{s1}(2460)$ states predicted by the naive quark model, but also in describing the $D_{s1}(2536)$ meson as the $1^{+}$ state of the $j_{q}^{P}=3/2^{+}$ doublet predicted by heavy quark symmetry and thus reproducing its strong decay properties. Two features of our formalism cannot be address nowadays by other approaches: the coupling of the $D$-wave $D^{\ast}K$ threshold in the $J^{P}=1^{+}$ $c\bar{s}$ channel and the computation of the probabilities associated with different Fock components in the physical state.