New charged resonance Z_{c}^{-}(4100): the spectroscopic parameters and width

H. Sundu,S. S. Agaev,K. Azizi

doi:10.1140/epjc/s10052-019-6737-0

Abstract

The mass, coupling and width of the newly observed charged resonance Z_{c}^{-}(4100) are calculated by treating it as a scalar four-quark system with a diquark–antidiquark structure. The mass and coupling of the state Z_{c}^{-}(4100) are calculated using the QCD two-point sum rules. In these calculations we take into account contributions of the quark, gluon and mixed condensates up to dimension ten. The spectroscopic parameters of Z_{c}^{-}(4100) obtained by this way are employed to study its S-wave decays to eta _c(1S)pi ^{-}, eta _c(2S)pi ^{-}, D^{0}D^{-}, and J/psi rho ^{-} final states. To this end, we evaluate the strong coupling constants corresponding to the vertices Z_{c}eta _c(1S)pi ^{-}, Z_{c}eta _c(2S)pi ^{-}, Z_{c}D^{0}D^{-}, and Z_{c}J/psi rho ^{-} respectively. The couplings g_{Z_ceta _{c1} pi }, g_{Z_{c}eta _{c2} pi }, and g_{Z_{c}DD} are computed by means of the QCD three-point sum rule method, whereas g_{Z_{c}J/psi rho } is obtained from the QCD light-cone sum rule approach and soft-meson approximation. Our results for the mass m=(4080 pm 150)~text {MeV} and total width Gamma =(147 pm 19)~mathrm { MeV} of the resonance Z_{c}^{-}(4100) are in excellent agreement with the existing LHCb data.

Highlights

The LHCb Collaboration reported on evidence for an ηc(1S)π − resonance in B0 → K +ηc(1S)π − decays extracted from analysis of pp collisions’ data co√llected with LHCb detector at center-of-mass energies of s = 7, 8 and 13 TeV [1]
The process Zc → J/ψρ− belongs to the second subclass of Zc decays; it is a decay to two vector mesons. We investigate this mode by means of the QCD light-cone sum rule method and soft-meson approximation
The mass and coupling of Zc have been evaluated by means of the two-point sum rule method, whereas its decay channels have been analyzed using the three-point and light-cone sum rule techniques

Summary

Introduction

Various theoretical models and approaches were employed to reveal the internal quark-gluon structure and determine parameters of the charged Z -resonances They were considered as hadrocharmonium compounds or tightly bound diquark–antidiquark states, were treated as the four-quark systems built of conventional mesons or interpreted as threshold cusps We calculate the partial width of the dominant S-wave processes and use obtained results to evaluate the total width of the tetraquark Zc. The decays Zc → ηc(1S)π −, ηc(2S)π −, and D0 D− are explored by applying the QCD three-point sum rule method. 2 we calculate the mass m and coupling f of the scalar resonance Zc by employing the two-point sum rule method and including into analysis the quark, gluon, and mixed condensates up to dimension ten. In the Appendix we write down explicit expressions of the heavy and light quark propagators, as well as the two-point spectral density used in the mass and coupling calculations

Mass and coupling of the scalar tetraquark Zc

M22 GeV2

Analysis and concluding remarks