English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Early speculations about the existence of heavy hadron molecules weregrounded on the idea that light-meson exchanges forces could lead to binding.In analogy to the deuteron, the light-mesons usually considered include thepion, sigma, rho and omega, but not the axial meson $a_1(1260)$. Though it hasbeen argued in the past that the coupling of the axial meson to the nucleons isindeed strong, its mass is considerably heavier than that of the vector mesonsand thus its exchange ends up being suppressed. Yet, this is not necessarilythe case in heavy hadrons molecules: we find that even though the contributionto binding from the axial meson is modest, it cannot be neglected in theisovector sector where vector meson exchange cancels out. This might provide anatural binding mechanism for molecular candidates such as the $Z_c(3900)$,$Z_c(4020)$ or the more recently observed $Z_{cs}(3985)$. However the$Z_{cs}(3985)$ is more dependent on a mixture of different factors, which(besides axial meson exchange) include $\eta$ exchange and the nature of scalarmeson exchange. Together they point towards the existence of two$Z_{cs}(3985)$-like resonances instead of one, while the observations about therole of scalar meson exchange in the $Z_{cs}(3985)$ might be relevant for the$P_{cs}(4459)$. Finally, the combination of axial meson exchange and flavorsymmetry breaking effects indicates that the isovector $J^{PC} = 0^{++}$$D^*\bar{D}^*$ and the strange $J^P = 2^{+}$ $D^*\bar{D}_s^*$ molecules are themost attractive configurations and thus the most likely molecular partners ofthe $Z_c(3900)$, $Z_c(4020)$ and $Z_{cs}(3985)$.

Axial meson exchange and the $Z_c(3900)$ and $Z_{cs}(3985)$ resonances as heavy hadron molecules