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By using 6.32 fbβ1 of data collected with the BESIII detector at center-of-mass energies between 4.178 and 4.226 GeV, we perform an amplitude analysis of the decay D+s ! K0S +β0 and determine the relative fractions and phase differences of different intermediate processes, which include K0S (770)+, K0S (1450)+, Kβ(892)0β+, Kβ(892)+β0, and Kβ(1410)0β+. With the detection efficiency based on the amplitude analysis results, the absolute branching fraction is measured to be B(D+s ! K0S +β0) = (5.43 Β± 0.30stat Β± 0.15syst) Γ 10β3.
Using (10.087Β±0.044)Γ109ββπ½/π events collected by the Beijing Spectrum III (BESIII) detector at the Beijing Electron Positron Collider II (BEPCII) collider, we search for the hyperon semileptonic decay ΞββΞ0β’πββ’Β―ππ. No significant signal is observed and the upper limit on the branching fraction β¬β‘(ΞββΞ0β’πββ’Β―ππ) is set to be 2.59Γ10β4 at 90% confidence level. This result is one order of magnitude more strict than the previous best limit.
Using inclusive decays of the J/Ο, a precise determination of the number of J/Ο events collected with the BESIII detector is performed. For the two data sets taken in 2009 and 2012, the numbers of J/Ο events are recalculated to be (224.0Β±1.3)Γ106 and (1088.5Β±4.4)Γ106 respectively, which are in good agreement with the previous measurements. For the J/Ο sample taken in 2017--2019, the number of events is determined to be (8774.0Β±39.4)Γ106. The total number of J/Ο events collected with the BESIII detector is determined to be (10087Β±44)Γ106, where the uncertainty is dominated by systematic effects and the statistical uncertainty is negligible.
We report a measurement of the observed cross sections of e+ eβ β J/ΟX based on 3.21 fb β 1 of data accumulated at energies from 3.645 to 3.891 GeV with the BESIII detector operated at the BEPCII collider. In analysis of the cross sections, we measured the decay branching fractions of B(Ο(3686) β J/ΟX) = (64.4 Β± 0.6 Β± 1.6)% and B(Ο(3770) β J/ΟX) = (0.5 Β± 0.2 Β± 0.1)% for the first time. The energy-dependent line shape of these cross sections cannot be well described by two Breit-Wigner (BW) amplitudes of the expected decays Ο (3686) β J/ΟX and Ο(3770) β J/ΟX. Instead, it can be better described with one more BW amplitude of the decay R(3760)β J/ΟX. Under this assumption, we extracted the R (3760) mass M R (3760 ) = 3766.2 Β± 3.8 Β± 0.4 MeV/c2, total width Ξ tot R ( 3760 ) = 22.2 Β± 5.9 Β± 1.4 MeV, and product of leptonic width and decay branching fraction
ΞeeR(3760) B[R(3760) β J/ΟX] = (79.4 Β± 85.5 Β± 11.7) eV. The significance of the R(3760) is 5.3Ο. The first uncertainties of these measured quantities are from fits to the cross sections and second systematic.
Based on an e+eβ collision data sample corresponding to an integrated luminosity of 2.93 fbβ1 collected with the BESIII detector at βs=3.773 GeV, the first amplitude analysis of the singly Cabibbo-suppressed decay D+βK+K0SΟ0 is performed. From the amplitude analysis, the Kβ(892)+K0S component is found to be dominant with a fraction of (57.1Β±2.6Β±4.2)%, where the first uncertainty is statistical and the second systematic. In combination with the absolute branching fraction B(D+βK+K0SΟ0) measured by BESIII, we obtain B(D+βKβ(892)+K0S)=(8.69Β±0.40Β±0.64Β±0.51)Γ10β3, where the third uncertainty is due to the branching fraction B(D+βK+K0SΟ0). The precision of this result is significantly improved compared to the previous measurement. This result also differs from most of theoretical predictions by about 4Ο, which may help to improve the understanding of the dynamics behind.
A search for the charged lepton flavor violating decay π½/πβπΒ±β’πβ with πββπββ’π0β’ππ is performed with about 10Γ109ββπ½/π events collected with the BESIII detector at the BEPCII. No significant signal is observed, and an upper limit is set on the branching fraction β¬β‘(π½/πβπΒ±β’πβ)<7.5Γ10β8 at the 90% confidence level. This improves the previously published limit by two orders of magnitude.
The decays D β KβΟ+Ο+Οβ and D β KβΟ+Ο 0 are studied in a sample of quantum-correlated DDΒ― pairs produced through the process e+eβ β Ο(3770) β DDΒ―, exploiting a data set collected by the BESIII experiment that corresponds to an integrated luminosity of 2.93 fbβ1 . Here D indicates a quantum superposition of a D0 and a DΒ― 0 meson. By reconstructing one neutral charm meson in a signal decay, and the other in the same or a different final state, observables are measured that contain information on the coherence factors and average strong-phase differences of each of the signal modes. These parameters are critical inputs in the measurement of the angle Ξ³ of the Unitarity Triangle in Bβ β DKβ decays at the LHCb and Belle II experiments. The coherence factors are determined to be RK3Ο = 0.52+0.12β0.10 and RKΟΟ0 = 0.78 Β± 0.04, with values for the average strong-phase differences that are Ξ΄ K3Ο D = (167+31β19)β¦ and Ξ΄KΟΟ0D = (196+14β15β¦ , where the uncertainties include both statistical and systematic contributions. The analysis is re-performed in four bins of the phase-space of the D β KβΟ+Ο+Οβ to yield results that will allow for a more sensitive measurement of Ξ³ with this mode, to which the BESIII inputs will contribute an uncertainty of around 6β¦.
Amplitude analysis and branching-fraction measurement of DββΊβββKββ°Kβ»ΟβΊΟβΊ
(2021)
Using 6.32ββfbβ1 of π+β’πβ collision data collected by the BESIII detector at the center-of-mass energies between 4.178 and 4.226 GeV, an amplitude analysis of the π·+π βπΎ0πβ’πΎββ’π+β’π+ decays is performed for the first time to determine the intermediate-resonant contributions. The dominant component is the π·+π βπΎ*β’(892)+β’Β―πΎ*β’(892)0 decay with a fraction of (40.6Β±2.β’9statΒ±4.β’9sys)%. Our results of the amplitude analysis are used to obtain a more precise measurement of the branching fraction of the π·+π βπΎ0πβ’πΎββ’π+β’π+ decay, which is determined to be (1.46Β±0.0β’5statΒ±0.0β’5sys)%.
We report new measurements of the branching fraction β¬β‘(π·+π ββ+β’π), where β+ is either π+ or π+β‘(βπ+β’Β―ππ), based on 6.32ββfbβ1 of electron-positron annihilation data collected by the BESIII experiment at six center-of-mass energy points between 4.178 and 4.226 GeV. Simultaneously floating the π·+π βπ+β’ππ and π·+π βπ+β’ππ components yields β¬β‘(π·+π βπ+β’ππ)=(5.21Β±0.25Β±0.17)Γ10β2, β¬β‘(π·+π βπ+β’ππ)=(5.35Β±0.13Β±0.16)Γ10β3, and the ratio of decay widths π
=Ξβ‘(π·+π βπ+β’ππ)Ξβ‘(π·+π βπ+β’ππ)=9.7β’3+0.61β0.58Β±0.36, where the first uncertainties are statistical and the second systematic. No evidence of πΆβ’π asymmetry is observed in the decay rates π·Β±π βπΒ±β’ππ and π·Β±π βπΒ±β’ππ: π΄πΆβ’πβ‘(πΒ±β’π)=(β1.2Β±2.5Β±1.0)% and π΄πΆβ’πβ‘(πΒ±β’π)=(+2.9Β±4.8Β±1.0)%. Constraining our measurement to the Standard Model expectation of lepton universality (π
=9.75), we find the more precise results β¬β‘(π·+π βπ+β’ππ)=(5.22Β±0.10Β±0.14)Γ10β2 and π΄πΆβ’πβ‘(πΒ±β’ππ)=(β0.1Β±1.9Β±1.0)%. Combining our results with inputs external to our analysis, we determine the πβΒ―π quark mixing matrix element, π·+π decay constant, and ratio of the decay constants to be |ππβ’π |=0.973Β±0.009Β±0.014, ππ·+π =249.9Β±2.4Β±3.5ββMeV, and ππ·+π /ππ·+=1.232Β±0.035, respectively.