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

Abstract

Early speculations about the existence of heavy hadron molecules were grounded on the idea that light-meson exchanges forces could lead to binding. In analogy to the deuteron, the light-mesons usually considered include the pion, sigma, rho and omega, but not the axial meson $a_1(1260)$. Though it has been argued in the past that the coupling of the axial meson to the nucleons is indeed strong, its mass is considerably heavier than that of the vector mesons and thus its exchange ends up being suppressed. Yet, this is not necessarily the case in heavy hadrons molecules: we find that even though the contribution to binding from the axial meson is modest, it cannot be neglected in the isovector sector where vector meson exchange cancels out. This might provide a natural 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 scalar meson exchange. Together they point towards the existence of two $Z_{cs}(3985)$-like resonances instead of one, while the observations about the role 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 flavor symmetry breaking effects indicates that the isovector $J^{PC}=0^{++}$ $D^{\ast }{\bar{D}}^{\ast }$ and the strange $J^P=2^{+}$ $D^{\ast }{\bar{D}}_s^{\ast }$ molecules are the most attractive configurations and thus the most likely molecular partners of the $Z_c(3900)$, $Z_c(4020)$ and $Z_{cs}(3985)$.

26 pages, 3 figures, 6 tables; tries to explain a few features of the Zc(3900), Zcs(3985) and Pcs(4459); corresponds to the published version

References in corpus (38)

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• Prediction of narrow $N^{\ast }$ and ${\Lambda }^{\ast }$ resonances with hidden charm above 4 GeV
• Dynamically Generated Open and Hidden Charm Meson Systems
• Evidence of a $J/\psi \Lambda$ structure and observation of excited ${\Xi }^{-}$ states in the ${\Xi }_b^{-}\to J/\psi \Lambda K^{-}$ decay
• Emergence of a complete heavy-quark spin symmetry multiplet: seven molecular pentaquarks in light of the latest LHCb analysis
• Strong LHCb evidence supporting the existence of the hidden-charm molecular pentaquarks
• X(3872) and Other Possible Heavy Molecular States
• Pion Interactions in the X(3872)
• The Heavy Quark Spin Symmetry Partners of the X(3872)
• Is X(3872) {\sl Really} a Molecular State?
• Observation of new resonances decaying to $J/\psi K^{+}$ and $J/\psi \varphi$
• Observation of a near-threshold structure in the $K^{+}$ recoil-mass spectra in $e^{+}{e}^{-}\to K^{+}(D_s^{-}{D}^{\ast 0}+D_s^{\ast -}{D}^0)$
• Study of $P_c(4457)$, $P_c(4440)$, and $P_c(4312)$ in a quasipotential Bethe-Salpeter equation approach
• Heavy quark spin symmetric molecular states from ${\bar{D}}^{(\ast )}{\Sigma }_c^{(\ast )}$ and other coupled channels in the light of the recent LHCb pentaquarks
• Isoscalar meson spectroscopy from lattice QCD
• Axial Resonances in the Open and Hidden Charm Sectors
• The Vector and Axial-Vector Charmonium-like States
• Anatomy of the newly observed hidden-charm pentaquark states: $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$
• Heavy-quark spin and flavour symmetry partners of the X(3872) revisited: what can we learn from the one boson exchange model?
• Establishing the first hidden-charm pentaquark with strangeness
• Clues for the existence of two $K_1(1270)$ resonances
• Charmonium-like resonances with $J^{PC}=0^{++},2^{++}$ in coupled $D\bar{D}$, $D_s{\bar{D}}_s$ scattering on the lattice
• Calculation of the heavy-hadron axial couplings g_1, g_2, and g_3 using lattice QCD
• The $P_{cs}(4459)$ pentaquark from a combined effective field theory and phenomenological perspective
• Strange molecular partners of the $Z_c(3900)$ and $Z_c(4020)$
• $P_{cs}(4459)$ and other possible molecular states from ${\Xi }_c^{(\ast )}{\bar{D}}^{(\ast )}$ and ${\Xi }_c^{\prime }{\bar{D}}^{(\ast )}$ interactions
• The "$a_1(1420)$" peak as the $\pi f_0(980)$ decay mode of the $a_1(1260)$
• Can the newly $P_{cs}(4459)$ be a strange hidden-charm ${\Xi }_c{\bar{D}}^{\ast }$ molecular pentaquarks?
• Can discovery of hidden charm strange pentaquark states help determine the spins of $P_c(4440)$ and $P_c(4457)$?
• Heavy-Quark Symmetry Partners of the Pc(4450) Pentaquark
• Decoding the nature of $Z_{cs}(3985)$ and establishing the spectrum of charged heavy quarkoniumlike states in chiral effective field theory
• The $Z_{cs}(3985)$ as a threshold effect from the ${\bar{D}}_s^{\ast }D+{\bar{D}}_s{D}^{\ast }$ interaction
• Revising the $f_1(1420)$ resonance
• Implications of the $Z_{cs}(3985)$ and $Z_{cs}(4000)$ as two different states
• Unveiling the $K_1(1270)$ double-pole structure in the $\bar{B}\to J/\psi \rho \bar{K}$ and $\bar{B}\to J/\psi {\bar{K}}^{\ast }\pi$ decays
• Serber symmetry, Large Nc and Yukawa-like One Boson Exchange Potentials
• Photoproduction of strange hidden-charm and hidden-bottom states
• Influence of Meson's Widths on Yukawa-like Potentials and Lattice Correlation Functions

Cited by in corpus (17)

• An updated review of the new hadron states
• Chiral perturbation theory for heavy hadrons and chiral effective field theory for heavy hadronic molecules
• Hadronic molecules in B decays
• Revisiting the $D{D}^{\ast }$ chiral interactions with the local momentum-space regularization up to the third order and the nature of $T_{cc}^{+}$
• A combined analysis of the $Z_c(3900)$ and the $Z_{cs}(3985)$ exotic states
• Hidden and doubly heavy molecular states from interactions $D_{(s)}^{(\ast )}{\bar{D}}_s^{(\ast )}$/$B_{(s)}^{(\ast )}{\bar{B}}_s^{(\ast )}$ and $D_{(s)}^{(\ast )}{D}_s^{(\ast )}$/$B_{(s)}^{(\ast )}{B}_s^{(\ast )}$
• Heavy- and light-flavor symmetry partners of the $T_{cc}^{+}(3875)$, the $X(3872)$ and the $X(3960)$ from light-meson exchange saturation
• Molecular charmed baryons and pentaquarks from light-meson exchange saturation
• Faddeev fixed-center approximation to the $D\bar{D}K$ system and the hidden charm $K_{c\bar{c}}(4180)$ state
• $Z_{cs}$ states from the $D_s^{\ast }{\bar{D}}^{\ast }$ and $J/\psi K^{\ast }$ coupled channels: Signal in $B^{+}\to J/\psi \varphi K^{+}$ decay
• $Z_{cs}(3985)$ in next-to-leading-order chiral effective field theory -- the first truncation uncertainty analysis
• Hadronic medium effects on $Z_{cs}(3985{)}^{-}$ production in heavy-ion collisions
• Search for hidden-charm tetraquark with strangeness in $e^{+}{e}^{-}\to K^{+}{D}_s^{\ast -}{D}^{\ast 0}+c.c.$
• The $Z_{cs}$ states and the mixture of hadronic molecule and diquark-anti-diquark components within effective field theory
• Hunting for the heavy quark spin symmetry partner of $Z_{cs}$
• Low-energy $N\varphi$ scattering from a pole-enhanced triangle diagram
• Decoding the near-threshold $X_{0,1}(4140)$ and $X_1(4685)$ states via OZI-suppressed coupled-channel scattering