Measurement of cross sections for $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}$ at center-of-mass energies from 3.80 to 4.60 GeV

Abstract

The observed cross sections for $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}$ at energies from 3.8 to 4.6 GeV are measured using data samples taken with the BESIII detector operated at the BEPCII collider. We measure the muonic widths and determine the branching fractions of the charmonium states $\psi (4040)$, $\psi (4160)$, and $\psi (4415)$ decaying to ${\mu }^{+}{\mu }^{-}$, as well as making a first determination of the phase of the amplitudes. In addition, we observe evidence for a structure in the dimuon cross section near 4.220 GeV/$c^2$, which we denote as $S(4220)$. Analyzing a coherent sum of amplitudes yields eight solutions, one of which gives a mass of $M_{S(4220)}=4216.7\pm 8.9\pm 4.1$~MeV/$c^2$, a total width of ${\mathrm{\Gamma }}_{\mathrm{S}(4220)}^{\mathrm{tot}}=47.2\pm 22.8\pm 10.5$~MeV, and a muonic width of ${\mathrm{\Gamma }}_{S(4220)}^{\mu \mu }=1.53\pm 1.26\pm 0.54$~keV, where the first uncertainties are statistical and the second systematic. The eight solutions give the central values of the mass, total width, muonic width to be, respectively, in the range from 4212.8 to 4219.4 MeV/$c^2$, from 36.4 to 49.6 MeV, and from 1.09 to 1.53 keV. The statistical significance of the $S(4220)$ signal is $3.9\sigma$. Correcting the total dimuon cross section for radiative effects yields a statistical significance for this structure of more than $7\sigma$.

8 pages, 3 figures

References in corpus (11)

• Heavy quarkonium: progress, puzzles, and opportunities
• Observation of Two Resonant Structures in e+e- to pi+ pi- psi(2S) via Initial State Radiation at Belle
• Higher Charmonia and X,Y,Z states with Screened Potential
• Precise measurement of the $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}J/\psi$ cross section at center-of-mass energies from 3.77 to 4.60 GeV
• Evidence of Two Resonant Structures in $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{h}_c$
• Matching perturbative and Parton Shower corrections to Bhabha process at flavour factories
• Study of $e^{+}{e}^{-}\to \omega {\chi }_{cJ}$ at center-of-mass energies from 4.21 to 4.42 GeV
• Measurements of the cross sections for $e^{+}{e}^{-}\to \mathrm{hadrons}$ at 3.650, 3.6648, 3.773 GeV and the branching fraction for $\psi (3770)\to \mathrm{non}-D\bar{D}$
• Measurements of the braching fractions for psi(3770)--> D0D0-bar,D+D-,DD-bar$ and the resonance parameters of psi(3770) and psi(2S)
• Photon pair production at flavour factories with per mille accuracy
• Measurements of the continuum $R_{\mathrm{uds}}$ and $R$ values in $e^{+}{e}^{-}$ annihilation in the energy region between 3.650 and 3.872 GeV

Cited by in corpus (6)

• Global coupled-channel analysis of $e^{+}{e}^{-}\to c\bar{c}$ processes in $\sqrt{s}=3.75-4.7$ GeV
• Observation of di-structures in $e^{+}{e}^{-}\to J/\psi \mathrm{X}$ at center-of-mass energies around 3.773 GeV
• First Observation of a Three-Resonance Structure in $e^{+}{e}^{-}\to$Nonopen Charm Hadrons
• $\mathcal{R}(3780)$ Resonance Interpreted as the $1^3{D}_1$-Wave Dominant State of Charmonium from Precise Measurements of the Cross Section of $e^{+}{e}^{-}\to$ Hadrons
• Production of $\psi (4040)$, $\psi (4160)$, and $\psi (4415)$ mesons in strong interactions
• Dissociation cross sections of $\psi (3770)$, $\psi (4040)$, $\psi (4160)$, and $\psi (4415)$ mesons with nucleons