$Z_c(4430)$ and $Z_c(4200)$ as triangle singularities

Abstract

$Z_c(4430)$ discovered by the Belle and confirmed by the LHCb in ${\bar{B}}^0\to \psi (2S)K^{-}{\pi }^{+}$ is generally considered to be a charged charmonium-like state that includes minimally two quarks and two antiquarks. $Z_c(4200)$ found in ${\bar{B}}^0\to J/\psi K^{-}{\pi }^{+}$ by the Belle is also a good candidate of a charged charmonium-like state. We demonstrate that kinematical singularities in triangle loop diagrams induce a resonance-like behavior that can consistently explain the properties (mass, width, and Argand plot) of $Z_c(4430)$ and $Z_c(4200)$ from the experimental analyses. The triangle diagrams include only experimentally well-established hadrons. Applying this idea to ${\Lambda }_b^0\to J/\psi p{\pi }^{-}$, we also identify triangle singularities that behave like $Z_c(4200)$, but no triangle diagram is available for $Z_c(4430)$. This is consistent with the LHCb's finding that their description of the ${\Lambda }_b^0\to J/\psi p{\pi }^{-}$ data is significantly improved by including a $Z_c(4200)$ contribution while $Z_c(4430)$ seems to hardly contribute. Even though the proposed mechanisms have uncertainty in the absolute strengths which are currently difficult to estimate, they are certainly a compelling alternative to tetraquark-based interpretations of $Z_c(4430)$ and $Z_c(4200)$.

6 pages, 5 figures; published version; one figure on the cutoff-dependence added

References in corpus (22)

• Heavy-Quark QCD Exotica
• Observation of a narrow pentaquark state, $P_c(4312{)}^{+}$, and of two-peak structure of the $P_c(4450{)}^{+}$
• Observation of a resonance-like structure in the pi^+- psi' mass distribution in exclusive B-->K pi^+- psi' decays
• Observation of the resonant character of the $Z(4430{)}^{-}$ state
• Exotic Hadrons with Heavy Flavors -X, Y, Z and Related States-
• The Z(4430) and a New Paradigm for Spin Interactions in Tetraquarks
• Observation of a new charged charmoniumlike state in B -> J/psi K pi decays
• A Discussion on Triangle Singularities in the ${\Lambda }_b\to J/\psi K^{-}p$ Reaction
• Evidence for exotic hadron contributions to ${\Lambda }_b^0\to J/\psi p{\pi }^{-}$ decays
• Excited heavy tetraquarks with hidden charm
• Is Z^+(4430) a loosely bound molecular state?
• How Resonances can synchronise with Thresholds
• Amplitude analysis and the nature of the Zc(3900)
• QCD sum rules study of the meson Z^+(4430)
• $\{Q\bar{q}\}\{{\bar{Q}}^{{(}^{\prime })}q\}$ molecular states
• Threshold effect and π^\pm ψ(2S) peak
• Charged charmonium-like Z+(4430) from rescattering in conventional B decays
• Model-independent observation of exotic contributions to $B^0\to J/\psi K^{+}{\pi }^{-}$ decays
• ${\mathrm{Z}}^{+}(4430)$ and Analogous Heavy Flavor States
• Exotic Four Quark Matter: $Z_1(4475)$
• Properties of $Z_c^{\pm }(3900)$ produced in $p\bar{p}$ collision
• Search for the $B\to Y(4260)K,Y(4260)\to J/\psi {\pi }^{+}{\pi }^{-}$ decays

Cited by in corpus (15)

• The $XYZ$ states: experimental and theoretical status and perspectives
• Pentaquark and Tetraquark states
• Electron-Ion Collider in China
• Heavy hadronic molecules with pion exchange and quark core couplings: a guide for practitioners
• Novel approaches in Hadron Spectroscopy
• XYZ spectroscopy at electron-hadron facilities: Exclusive processes
• Triangle Singularity as the Origin of the $a_1(1420)$
• The hidden-charm strong decays of the $Z_c$ states
• Classifying Pole of Amplitude Using Deep Neural Network
• Triangle singularity appearing as an $X(3872)$-like peak in $B\to (J/\psi {\pi }^{+}{\pi }^{-})K\pi$
• $S$-wave contributions to the $B_{(s)}\to {\chi }_{c1}(\pi \pi ,K\pi ,KK)$ decays
• $Z_c(4430)$, $Z_c(4200)$, $Z_1(4050)$, and $Z_2(4250)$ as triangle singularities
• An $X(3872)$-like peak in $B\to (J/\psi {\pi }^{+}{\pi }^{-})K\pi$ due to triangle singularity
• Observation and investigation of the $T_{c\bar{c}1}(4430{)}^{+}$ structure in $B^{+}\to \psi (2S)K_{\text{S}}^0{\pi }^{+}$ decays
• Exotic hadrons associated with $b$-quark