1 Ocak 2019 Dergi makalesi Açık Erişim

CERN İşbirliği

Citation Style Language JSON

{
  "DOI": "10.1016/j.physletb.2019.03.001", 
  "abstract": "<p>Using 16 energy points of ${e}^{+}{e}^{-}$ annihilation data collected in the vicinity of the $J/\\psi $ resonance with the BESIII detector and with a total integrated luminosity of around $100\\phantom{\\rule{0.25em}{0ex}}{\\text{pb}}^{-1}$, we study the relative phase between the strong and electromagnetic amplitudes of $J/\\psi $ decays. The relative phase between $J/\\psi $ electromagnetic decay and the continuum process (${e}^{+}{e}^{-}$ annihilation without the $J/\\psi $ resonance) is confirmed to be zero by studying the cross section lineshape of ${\\mu }^{+}{\\mu }^{-}$ production. The relative phase between $J/\\psi $ strong and electromagnetic decays is then measured to be ${\\left(84.9\u00b13.6\\right)}^{\\circ }$ or ${\\left(-84.7\u00b13.1\\right)}^{\\circ }$ for the $2\\left({\\pi }^{+}{\\pi }^{-}\\right){\\pi }^{0}$ final state by investigating the interference pattern between the $J/\\psi $ decay and the continuum process. This is the first measurement of the relative phase between $J/\\psi $ strong and electromagnetic decays into a multihadron final state using the lineshape of the production cross section. We also study the production lineshape of the multihadron final state $\\eta {\\pi }^{+}{\\pi }^{-}$ with $\\eta \\to {\\pi }^{+}{\\pi }^{-}{\\pi }^{0}$, which provides additional information about the phase between the $J/\\psi $ electromagnetic decay amplitude and the continuum process. Additionally, the branching fraction of $J/\\psi \\to 2\\left({\\pi }^{+}{\\pi }^{-}\\right){\\pi }^{0}$ is measured to be $\\left(4.73\u00b10.44\\right)\\text{%}$ or $\\left(4.85\u00b10.45\\right)\\text{%}$, and the branching fraction of $J/\\psi \\to \\eta {\\pi }^{+}{\\pi }^{-}$ is measured to be $\\left(3.78\u00b10.68\\right)\u00d7{10}^{-4}$. Both of them are consistent with the world average values. The quoted uncertainties include both statistical and systematic uncertainties, which are mainly caused by the low statistics.</p>", 
  "author": [
    {
      "family": "CERN \u0130\u015fbirli\u011fi"
    }
  ], 
  "container_title": "Physics Letters B", 
  "id": "105997", 
  "issued": {
    "date-parts": [
      [
        2019, 
        1, 
        1
      ]
    ]
  }, 
  "title": "Measurement of the phase between strong and electromagnetic amplitudes of / Decays", 
  "type": "article-journal", 
  "volume": "791 C"
}