Engineering topics
Greco, M.
Publications and source records attributed to Greco, M..
Luminosity measurements for the R scan experiment at BESIII
By analyzing the large-angle Bhabha scattering events e + e - → (γ)e + e - and diphoton events e + e - → (γ)γγ for the data sets collected at center-of-mass (c.m.) energies between 2.2324 and 4.5900 GeV (131 energy points in total) with the upgraded Beijing Spectrometer (BESIII) at the Beijing Electron-Positron Collider (BEPCII), the integrated luminosities have been measured at the different c.m. energies, individually. Finally, the results are important inputs for the R value and J/ψ resonance parameter measurements.
Amplitude Analysis of the Decays η ' → π + π - π 0 and η ' → π 0 π 0 π 0
Based on a sample of 1.31 × 10 9 J / ψ events collected with the BESIII detector, an amplitude analysis of the isospin-violating decays η'→ π + π - π 0 and η' → π 0 π 0 π 0 is performed. A significant P-wave contribution from η'→ ρ ± π ∓ is observed for the first time in η' → π + π - π 0 . The branching fraction is determined to be B ( η'→ ρ ± π ∓ ) = ( 7.44 ± 0.60 ± 1.26 ± 1.84 ) × 10 -4 , where the first uncertainty is statistical, the second systematic, and the third model dependent. In addition to the nonresonant S -wave component, there is a significant σ meson component. The branching fractions of the combined S -wave components are determined to be B ( η' → π + π - π 0 ) S = ( 37.63 ± 0.77 ± 2.22 ± 4.48 ) × 10 -4 and B ( η' → π 0 π 0 π 0 ) = ( 35.22 ± 0.82 ± 2.54 ) × 10 -4 , respectively. Finally, the latter one is consistent with previous BESIII measurements.
Measurements of the branching fractions for D + → K S 0 K S 0 K + , K S 0 K S 0 π + and D 0 → K S 0 K S 0 , K S 0 K S 0 K S 0
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Measurements of the absolute branching fractions for D s + → η e + ν e and D s + → η ′ e + ν e
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Measurement of Singly Cabibbo Suppressed Decays Λ c + → p π + π − and Λ c + → p K + K −
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Measurement of the absolute branching fraction of D + → $\bar{K}$ 0 e + ν e via $\bar{K}$ 0 → π 0 π 0
By analyzing 2.93 fb–1 data collected at the center-of-mass energy with the BESIII detector, we measure the absolute branching fraction of the semileptonic decay D+ → $\bar{K}$0 e+νe to be Β(D + → $\bar{K}$ 0 e + ν e ) = (8.59 ± 0.14 ± 0.21)% using $\bar{K}$ 0 → K 0 s → π 0 π 0 , where the first uncertainty is statistical and the second systematic. Finally, our result is consistent with previous measurements within uncertainties..
Measurement of the D s + → ℓ + ν ℓ branching fractions and the decay constant f D s +
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Measurement of the leptonic decay width of J/ψ using initial state radiation
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Determination of the number of J/ψ events with inclusive J/ψ decays
A measurement of the number of J/ψ events collected with the BESIII detector in 2009 and 2012 is performed using inclusive decays of the J/ψ. The number of J/ψ events taken in 2009 is recalculated to be (223.7 ± 1.4) × 10 6 , which is in good agreement with the previous measurement, but with significantly improved precision due to improvements in the BESIII software. The number of J/ψ events taken in 2012 is determined to be (1086.9 ± 6.0) × 10 6 . In total, the number of J/ψ events collected with the BESIII detector is measured to be (1310.6 ± 7.0) × 10 6 , where the uncertainty is dominated by systematic effects and the statistical uncertainty is negligible.
Observation of e + e − → η ′ J / ψ at center-of-mass energies between 4.189 and 4.600 GeV
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Improved measurement of the absolute branching fraction of $D^{+}\rightarrow \bar{K}^0 \mu ^{+}\nu _{\mu }$
Here, by analyzing 2.93 fb -1 of data collected at √s = 3.773 GeV with the BESIII detector, we measure the absolute branching fraction B(D + → K¯ 0 μ + ν μ ) = (8.72 ± 0.07 stat. ± 0.18 sys. )%, which is consistent with previous measurements within uncertainties but with significantly improved precision. Combining the Particle Data Group values of B(D 0 → K - μ + ν μ ), B(D + → K¯ 0 e + ν e ), and the lifetimes of the D 0 and D + mesons with the value of B(D + → K¯ 0 μ + ν μ ) measured in this work, we determine the following ratios of partial widths: Γ(D 0 → K - μ + ν μ )/Γ(D + → K¯ 0 μ + ν μ ) = 0.963 ± 0.044 and Γ(D + → K¯ 0 μ + ν μ )/Γ(D + → K¯ 0 e + ν e ) = 0.988 ± 0.033.
Measurements of the center-of-mass energies at BESIII via the di-muon process
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 - → γ ISR/FSR μ + μ - , 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 the time during data taking.