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Register a new userMeasurement of the center-of-mass energies at BESIII via the di-muon process
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From 2011 to 2014, the BESIII experiment collected about 5 fb$^{-1}$ data at center-of-mass energies around 4 GeV for the studies of the charmonium-like and higher excited charmonium states. By analyzing the di-muon process $e^{+}e^{-}rightarrowgamma_{rm ISR/FSR}mu^{+}mu^{-}$, the center-of-mass energies of the data samples are measured with a precision of 0.8 MeV. The center-of-mass energy is found to be stable for most of time during the data taking.
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During the 2016-17 and 2018-19 running periods, the BESIII experiment collected 7.5~fb$^{-1}$ of $e^+e^-$ collision data at center-of-mass energies ranging from 4.13 to 4.44 GeV. These data samples are primarily used for the study of excited charmonium and charmoniumlike states. By analyzing the di-muon process $e^{+}e^{-} to (gamma_{rm ISR/FSR}) mu^{+}mu^{-}$, we measure the center-of-mass energies of the data samples with a precision of 0.6 MeV. Through a run-by-run study, we find that the center-of-mass energies were stable throughout most of the data-taking period.
From December 2011 to May 2014, about 5 $rm fb^{-1}$ of data were taken with the BESIII detector at center-of-mass energies between 3.810 GeV and 4.600 GeV to study the charmoniumlike states and higher excited charmonium states. The time integrated luminosity of the collected data sample is measured to a precision of 1% by analyzing events produced by the large-angle Bhabha scattering process.
The process $e^{+}e^{-} rightarrow phieta$ is studied at 22 center-of-mass energy points ($sqrt{s}$) between 2.00 and 3.08 GeV using 715 pb$^{-1}$ of data collected with the BESIII detector. The measured Born cross section of $e^{+}e^{-} rightarrow phieta$ is found to be consistent with {textsl{BABAR}} measurements, but with improved precision. A resonant structure around 2.175 GeV is observed with a significance of 6.9$sigma$ with mass ($2163.5pm6.2pm3.0$) MeV/$c^{2}$ and width ($31.1_{-11.6}^{+21.1}pm1.1$) MeV, where the first uncertainties are statistical and the second are systematic.
To study the nature of the state $Y(2175)$, a dedicated data set of $e^+e^-$ collision data was collected at the center-of-mass energy of 2.125 GeV with the BESIII detector at the BEPCII collider. By analyzing large-angle Bhabha scattering events, the integrated luminosity of this data set is determined to be $108.49pm0.02pm0.85$ pb$^{-1}$, where the first uncertainty is statistical and the second one is systematic. In addition, the center-of-mass energy of the data set is determined with radiative dimuon events to be $2126.55pm0.03pm0.85$ MeV, where the first uncertainty is statistical and the second one is systematic.
We report a measurement of the observed cross sections of the inclusive $J/psi$ production in $e^+e^-rightarrow {J}/psi{rm X}$ based on 3.21 fb$^{-1}$ of data accumulated at energies from 3.645 to 3.891 GeV with the BESIII detector operated at the BEPCII collider. The energy-dependent lineshape obtained from the measured cross sections cannot be well described by two Breit-Wigner (BW) amplitudes of the expected decays $psi(3686)rightarrow {J}/psi{rm X}$ and $psi(3770)rightarrow {J}/psi{rm X}$. Instead it can be better described with three BW amplitudes of the decays $psi(3686)rightarrow {J}/psi{rm X}$, $R(3760)rightarrow {J}/psi{rm X}$ and $R(3790)rightarrow {J}/psi{rm X}$ with two distinct structures referred to as $R(3760)$ and $R(3790)$. Under this assumption, we extracted their masses, total widths, and the product of the leptonic width and decay branching fractions to be $M_{R(3760)}= {3761.7pm 2.2 pm 1.2}$ MeV/$c^2$, $Gamma^{rm tot}_{R(3760)}= {6.7pm 11.1 pm 1.1}$ MeV, $Gamma^{ee}_{R(3760)}mathcal B[R(3760)rightarrow {J}/psi {rm X}]=(4.0pm 4.3pm 1.2)$ eV, $M_{R(3790)} = {3784.7pm 5.7 pm 1.6}$ MeV/$c^2$, $Gamma^{rm tot}_{R(3790)} = {31.6 pm 11.9 pm 3.2}$ MeV, $Gamma^{ee}_{R(3790)}mathcal B[R(3790)rightarrow {J}/psi {rm X}]=(18.1pm 10.3pm 4.7)$ eV, where the first uncertainties are statistical and second systematic.
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