Engineering topics
Gradl, W.
Publications and source records attributed to Gradl, W..
Number of J/ψ events at BESIII*
Using inclusive decays of $J/\psi $, a precise determination of the number of $J/\psi $ events collected with the BESIII detector was performed. For the two data sets taken in 2009 and 2012, the numbers of $J/\psi $ events were recalculated to be $ (224.0 \pm 1.3)\times10^6 $ and $ (1088.5 \pm 4.4)\times10^6 $, respectively; these numbers are in good agreement with the previous measurements. For the $J/\psi $ sample taken in 2017–2019, the number of events was determined to be $ (8774.0 \pm 39.4)\times10^{6} $. The total number of $J/\psi $ events collected with the BESIII detector was determined to be $ (10087 \pm 44)\times10^{6} $, where the uncertainty is dominated by systematic effects, and the statistical uncertainty is negligible.
Cross section measurements of the $e^+e^–$ → $D^{*+}D^{*–}$ and $e^+e^–$ → $D^{*+}D^{–}$ processes at center-of-mass energies from 4.085 to 4.600 GeV
The Born cross sections of the $e^+e^–$ → $D^{*+}D^{*–}$ and $e^+e^–$ → $D^{*+}D^{–}$ processes are measured using $e^+e^–$ collision data collected with the BESIII experiment at center-of-mass energies from 4.085 to 4.600 GeV, corresponding to an integrated luminosity of 15.7 fb -1 . The results are consistent with and more precise than the previous measurements by the Belle, Babar and CLEO collaborations. The measurements are essential for understanding the nature of vector charmonium and charmonium-like states.
Measurements of absolute branching fractions of D 0 → K L 0 ϕ , K L 0 η , K L 0 ω , and K L 0 η ′
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Search for new hadronic decays of $h_c$ and observation of $h_c$ → $p\overline{p}η$
A search for the hadronic decays of the $h_c$ meson to the final states $p\overline{p}π^+π^-π^o$, $p\overline{p}η$, and $p\overline{p}π^o$ via the process $\psi$(3686) → $π^oh_c$ is performed using (4.48 ± 0.03) x 10 8 $\psi$(3686) events collected with the BESIII detector. The decay channel $h_c$ → $p\overline{p}η$ is observed for the first time with a significance greater than 5σ and a branching fraction of (6.41 ± 1.74 ± 0.53 ± 1.00) x 10 -4 , where the uncertainties are statistical, systematic, and that from the branching fraction of $\psi$(3686) → $π^oh_c$. Strong evidence for the decay $h_c$ → $p\overline{p}π^+π^-π^o$ is found with a significance of 4.9σ and a branching fraction of (3.84 ± 0.83 ± 0.69 ± 0.58) x 10 -3 . The significances include systematic uncertainties. No clear signal of the decay $h_c$ → $p\overline{p}π^o$ is found, and an upper limit of 6.59 x 10 -4 on its branching fraction is set at the 90% confidence level.
Search for the decay $h_c$ → $π^0J/ψ$
A search for the decay $h_c$ → $π^0J/ψ$ is performed using a sample of hc produced in the reaction $e^+e^-$ → $π^+π^-h_c$. The data samples were collected with the BESIII detector at center-of-mass energies between 4.189 and 4.437 GeV, corresponding to a total integrated luminosity of 11 fb -1 . No significant signal is observed. Upper limits on the branching ratio $\mathcal{B}$($h_c$ →$π^oJ/ψ$)/$\mathcal{B}$($h_c$ →$γη_c$ →$γK^+K_-π^o$) and on the branching fraction $\mathcal{B}$($h_c$ →$π^oJ/ψ$) are determined to be 7.5 x 10 -2 and 4.7 x 10 -4 at 90% confidence level, respectively. The latter is derived from the former using the measured branching fraction of the normalization channel. This is the first determination of the upper limit of the decay $h_c$ → $π^0J/ψ$
Search for X ( 3872 ) → π 0 χ c 0 and X ( 3872 ) → π π χ c 0 at BESIII
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Search for invisible decays of the Λ baryon
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Partial wave analysis of J / ψ → γ η ′ η ′
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Amplitude analysis and branching-fraction measurement of $\mathrm{D}^+_s$ → $π^+π^oη'$
Using data collected with the BESIII detector in $e^+e^-$ collisions at center-of-mass energies between 4.178 and 4.226 GeV and corresponding to 6.32 fb -1 of integrated luminosity, we report the amplitude analysis and branching-fraction measurement of the $\mathrm{D}^+_s$ → $π^+π^oη'$ decay. We find that the dominant intermediate process is $\mathrm{D}^+_s$ →$ρ^+η'$ and the significances of other resonant and nonresonant processes are all less than 3σ. The upper limits on the branching fractions of S-wave and P-wave nonresonant components are set to 0.10% and 0.74% at the 90% confidence level, respectively. In addition, the branching fraction of the $\mathrm{D}^+_s$ → $π^+π^oη'$ decay is measured to be (6.15 ± 0.25(stat.) ± 0.18(syst.))%, which receives significant contribution only from $\mathrm{D}^+_s$ →$ρ^+η'$ according to the amplitude analysis.
Observation of the Singly Cabibbo Suppressed Decay Λ c + → n π +
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Measurement of Compton Scattering at MAMI for the Extraction of the Electric and Magnetic Polarizabilities of the Proton
A precise measurement of the differential cross sections dσ/dΩ and the linearly polarized photon beam asymmetry Σ 3 for Compton scattering on the proton below pion threshold has been performed with a tagged photon beam and almost 4π detector at the Mainz Microtron. The incident photons were produced by the recently upgraded Glasgow-Mainz photon tagging facility and impinged on a cryogenic liquid hydrogen target, with the scattered photons detected in the Crystal Ball/TAPS setup. Using the highest statistics Compton scattering data ever measured on the proton along with two effective field theories (both covariant baryon and heavy-baryon) and one fixed-t dispersion relation model, constraining the fits with the Baldin sum rule, we have obtained the proton electric and magnetic polarizabilities with unprecedented precision: α E1 = 10.99 ± 0.16 ± 0.47 ± 0.17 ± 0.34, β M1 = 3.14 ± 0.21 ± 0.24 ± 0.20 ± 0.35; in units of 10 -4 fm 3 where the errors are statistical, systematic, spin polarizability dependent, and model dependent.
Study of the decay D s + → K S 0 K S 0 π + and observation of an isovector partner to f 0 ( 1710 )
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Observation of D 0 ( + ) → K S 0 π 0 ( + ) ω and improved measurement of D 0 → K − π + ω
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Study of light scalar mesons through D s + → π 0 π 0 e + ν e and K S 0 K S 0 e + ν e decays
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Search for baryon- and lepton-number violating decays D 0 → p ¯ e + and D 0 → p e −
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Measurement of the e + e − → ω π 0 π 0 cross section at center-of-mass energies from 2.0 to 3.08 GeV
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