Based on a sample of 1.31×109 J/ψ events collected with the BESIII detector, the matrix elements for the decays η′→ηπ+π− and η′→ηπ0π0 are determined using 351,016 η′→(η→γγ)π+π− and 56,249 ...η′→(η→γγ)π0π0 events with background levels less than 1%. Two commonly used representations are used to describe the Dalitz plot density. We find that an assumption of a linear amplitude does not describe the data well. A small deviation of the obtained matrix elements between η′→ηπ+π− and η′→ηπ0π0 is probably caused by the mass difference between charged and neutral pions or radiative corrections. No cusp structure in η′→ηπ0π0 is observed.
Using (10.087±0.044)×109 J/ψ 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 ... . No significant signal is observed and the upper limit on the branching fraction ... is set to be 2.59×10−4 at 90% confidence level. This result is one order of magnitude more strict than the previous best limit.(ProQuest: … denotes formulae omitted.)
By analyzing e(+)e(-) annihilation data with an integrated luminosity of 2.93 fb(-1) collected at the center-of-mass energy root s = 3.773 GeV with the BESIII detector, we present the first absolute ...measurements of the branching fractions of twenty Cabibbo-suppressed hadronic D0(+) decays involving multiple pions. The highest four branching fractions obtained are B(D-0 -> pi(+)pi(-)pi(0)) = (1.343 +/- 0.013(stat) +/- 0.016(syst))%, B(D-0 -> pi(+)pi(-)2 pi(0)) = (1.002 +/- 0.019(stat )+/- 0.024(syst))%, B(D-0 -> 2 pi(+)pi(-)pi(0))=(1.165 +/- 0.021(stat) +/- 0.021(sy)(st))%, and B(D+ -> 2 pi(+)pi(-)pi(0)). (1.074 +/- 0.040(stat) 0.030(syst))%. The CP asymmetries for the six decays with highest signal yields are also determined and found to be compatible with zero.
The singly Cabibbo-suppressed decay Lambda(+)(c) -> n pi(+) e is observed for the first time with a statistical significance of 7.3 sigma by using 3.9 fb(-1) of e(+)e(-) collision data collected ...at center-of-mass energies between 4.612 and 4.699 GeV with the BESIII detector at BEPCII. The branching fraction of Lambda(+)(c) -> n pi(+) is measured to be (6.6 +/- 1.2(stat) 0.4(syst)) x 10(-4). By taking the upper limit of branching fractions of Lambda(+)(c) -> n pi(+) from the Belle experiment, the ratio of branching fractions between Lambda(+)(c) -> n pi(+) and Lambda(+)(c) -> p pi(0) is calculated to be larger than 7.2 at the 90% confidence level, which disagrees with most predictions of the available phenomenological models. In addition, the branching fractions of the Cabibbo-favored decays Lambda(+)(c) -> Lambda pi(+) and Lambda(+)(c)-> Sigma(0)(pi+) are measured to be (1.31 +/- 0.08(stat) +/- 0.05(syst)) x 10(-2) and (1.22 +/- 0.08(stat) +/- 0.07(syst)) x 10(-2), respectively, which are consistent with previous results.
Using data samples collected with the BESIII detector operating at the BEPCII storage ring, the cross section of the inclusive process e + e − → η + X , normalized by the total cross section of e + e ...− → hadrons , is measured at eight center-of-mass energy points from 2.0000 to 3.6710 GeV. These are the first measurements with momentum dependence in this energy region. Our measurement shows a significant discrepancy compared to the existing fragmentation functions. To address this discrepancy, a new QCD analysis is performed at the next-to-next-to-leading order with hadron mass corrections and higher twist effects, which can explain both the established high-energy data and our measurements reasonably well. Published by the American Physical Society 2024
The decay J/ψ→γγϕ is studied using a sample of 1.31×109 J/ψ events collected with the BESIII detector. Two structures around 1475 MeV/c2 and 1835 MeV/c2 are observed in the γϕ invariant mass ...spectrum for the first time. With a fit on the γϕ invariant mass, which takes into account the interference between the two structures, and a simple analysis of the angular distribution, the structure around 1475 MeV/c2 is found to favor an assignment as the η(1475) and the mass and width for the structure around 1835 MeV/c2 are consistent with the X(1835). The statistical significances of the two structures are 13.5σ and 6.3σ, respectively. The results indicate that both η(1475) and X(1835) contain a sizeable ss¯ component.
Based on 7.33 fb −1 of e + e − collision data collected at center-of-mass energies between 4.128 and 4.226 GeV with the BESIII detector, the experimental studies of the doubly Cabibbo-suppressed ...decays Ds + →K + K + π − and D + s →K + K + π − π 0 are reported. We determine the absolute branching fraction of Ds + →K + K + π − to be (1.24 +0.28 −0.26 (stat)±0.06(syst))×10 −4 . No significant signal of D + s →K + K + π − π 0 is observed and the upper limit on its decay branching fraction at 90% confidence level is set to be 1.7×10 −4 .
Using o1.0087 similar to 0.0044THORN x 1010 J=. events collected by the BESIII detector at the BEPCII collider, we report the first search for the baryon and lepton number violating decays.0. ...K-ethorn with.oB - LTHORN 1/4 0 and.0. Kthorne- with j.oB - LTHORNj 1/4 2, where B (L) is the baryon (lepton) number. While no signal is observed, the upper limits on the branching fractions of these two decays are set to Bo.0. K-ethornTHORN < 3.6 x 10- 6 and Bo.0. Kthorne- THORN < 1.9 x 10- 6 at the 90% confidence level, respectively. These results offer a direct probe of baryon number violating interactions involving a strange quark.
A bstract Based on e + e − collision data collected at center-of-mass energies from 2.000 to 3.080 GeV by the BESIII detector at the BEPCII collider, a partial wave analysis is performed for the ...process e + e − → $$ {K}_S^0{K}_L^0 $$ K S 0 K L 0 π 0 . The results allow the Born cross sections of the process e + e − → $$ {K}_S^0{K}_L^0 $$ K S 0 K L 0 π 0 , as well as its subprocesses e + e − → K ∗ (892) 0 $$ \overline{K} $$ K ¯ 0 and $$ {K}_2^{\ast } $$ K 2 ∗ (1430) 0 $$ \overline{K} $$ K ¯ 0 to be measured. The Born cross sections for e + e − → $$ {K}_S^0{K}_L^0 $$ K S 0 K L 0 π 0 are consistent with previous measurements by BaBar, but with substantially improved precision. The Born cross section lineshape of the process e + e − K ∗ (892) 0 $$ \overline{K} $$ K ¯ 0 is consistent with a vector meson state around 2.2 GeV with a significance of 3.2 σ . A Breit-Wigner fit determines its mass as M Y = (2164 . 7 ± 9 . 1 ± 3 . 1) MeV /c 2 and its width as Γ Y = (32 . 4 ± 21 . 0 ± 1 . 8) MeV.
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