{
  "id": "1903.08458",
  "version": "v1",
  "published": "2019-03-20T11:50:22.000Z",
  "updated": "2019-03-20T11:50:22.000Z",
  "title": "The role of charged exotic states in $e^+e^- \\to ψ(2S) \\; π^+ π ^-$",
  "authors": [
    "Daniel A. S. Molnar",
    "Igor Danilkin",
    "Marc Vanderhaeghen"
  ],
  "categories": [
    "hep-ph"
  ],
  "abstract": "In this work, we use the dispersion theory to provide a physical description of recent BESIII data on the reaction $ e^+ e^- \\to \\psi (2S) \\, \\pi^+ \\, \\pi^-$. Taking into account explicitly the effects of charged exotic intermediate states in the $t$- and $u$-channels as well as the two-pion final state interaction, we describe the invariant mass distribution for four different $e^+ e^-$ center-of-mass energies. The effects of the $\\pi\\pi$ rescattering are accounted for within a model-independent single channel approach which is found to explain the $\\pi \\pi$-invariant mass distributions at all $e^+ e^-$ center-of-mass energies. For $q= 4.226$ GeV and $q= 4.258$ GeV the already established charged exotic state $Z_c(3900)$ is considered as the intermediate state, whereas for $q= 4.358$ GeV the rescattering of pions dominates the fits. For the highest energy, $q= 4.416$ GeV, a heavier charged exotic state with mass $m_{Z_c} = 4.016(4)$ GeV and width $\\Gamma_{Z_c} = 52(10)$ MeV is essential to describe the experimental data. Although the mass of this state is consistent with the established $Z_c(4020)$, its width is significantly larger.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2019-03-20T11:50:22.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "invariant mass distribution",
      "two-pion final state interaction",
      "center-of-mass energies",
      "model-independent single channel approach",
      "charged exotic intermediate states"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}