2,195 research outputs found
Improved measurement of the branching fractions for J/ψ →γπ0, γη, and γη′
No full textUsing a data sample of (1.0087±0.0044)×1010 J/ψ events collected with the BESIII detector, the decays of J/ψ→γπ0(η,η′)→γγγ are studied. Newly measured branching fractions are B(J/ψ→γπ0)=(3.34±0.02±0.09)×10-5, B(J/ψ→γη)=(1.096±0.001±0.019)×10-3, and B(J/ψ→γη′)=(5.40±0.01±0.11)×10-3, where the first uncertainties are statistical and the second are systematic. These results are consistent with the world average values within two standard deviations. The ratio of partial widths Γ(J/ψ→γη′)/Γ(J/ψ→γη) is measured to be 4.93±0.13. The singlet-octet pseudoscalar mixing angle θP is determined to be θP=-(22.11±0.26)° or -(19.34±0.34)° with two different phenomenological models. © 2023 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.<br/
Observation and branching fraction measurement of the decay J/ψ → p ¯ ς+ KS0 + c. c.
No full textThe first observation of the decays J/ψ→p¯ς+KS0 and J/ψ→pς¯-KS0 is reported using (10087±44)×106 J/ψ events recorded by the BESIII detector at the BEPCII storage ring. The branching fractions of each channel are determined to be B(J/ψ→p¯ς+KS0)=(1.361±0.006±0.025)×10-4, and B(J/ψ→pς¯-KS0)=(1.352±0.006±0.025)×10-4. The combined result is B(J/ψ→p¯ς+KS0+c.c.)=(2.725±0.009±0.050)×10-4, where the first uncertainty is statistical and the second systematic. The results presented are in good agreement with the branching fractions of the isospin partner decay J/ψ→pK-ς¯0+c.c. © 2024 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.<br/
Observation of the decay J/ψ →e+e-η (1405) with η (1405) →π0f0 (980)
No full textUsing a data sample of (10087±44)×106 J/ψ events collected by the BESIII detector in 2009, 2012, 2018 and 2019, the electromagnetic Dalitz process J/ψ→e+e-η(1405) is observed via the decay η(1405)→π0f0(980), f0(980)→π+π-, with a significance of about 9.8σ. The branching fraction of this decay is measured to be B(J/ψ→e+e-η(1405)→e+e-π0f0(980)→e+e-π0π+π-)=(2.04±0.20(stat)±0.08(syst))×10-7. The branching fraction ratio B(J/ψ→e+e-η(1405))/B(J/ψ→γη(1405)) is determined to be (1.36±0.17(stat)±0.06(syst))×10-2. Furthermore, an e+e- invariant mass dependent transition form factor of J/ψ→e+e-η(1405) is presented for the first time. The obtained result provides input for different theoretical models and is valuable for the improved understanding the intrinsic structure of the η(1405) meson. © 2024 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.<br/
Observation of J / ψ decays to e + e − e + e − and e + e − μ + μ −
No full textUsing a data sample of 4.481×108 ψ(3686) events collected with the BESIII detector, we report the first observation of the four-lepton-decays J/ψ→e+e-e+e- and J/ψ→e+e-μ+μ- utilizing the process ψ(3686)→π+π-J/ψ. The branching fractions are determined to be [5.48±0.31(stat)±0.45(syst)]×10-5 and [3.53±0.22(stat)±0.13(syst)]×10-5, respectively. The results are consistent with theoretical predictions. No significant signal is observed for J/ψ→μ+μ-μ+μ-, and an upper limit on the branching fraction is set at 1.6×10-6 at the 90% confidence level. A CP asymmetry observable is constructed for the first two channels, which is measured to be (-0.012±0.054±0.010) and (0.062±0.059±0.006), respectively. No evidence for CP violation is observed in this process. © 2024 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3
Helicity Amplitude Analysis of Z(c)(3900)(+/-) in e(+)e(-) -> pi(+)pi(-) J/psi
No full textIt is crucial to determine the spin and parity (J(p)) of Z(c)(3900)(+/-) for understanding its structure. We perform a helicity amplitude analysis on Z(c)(3900)(+/-) in the process e(+)e(-) -> pi(+)pi(-) J/psi with the hypotheses Jp = 0(-), 1(+), 1(-), 2(+) and 2(-). To estimate the significance of Jp = 1(+) over other hypotheses, we perform a Monte Carlo simulation study, and we also discuss the prospect of measuring the spin parity in the future experiment with a large data sample
pi-pi correlations in photon-induced reactions
No full textDifferential cross sections of the-reactions A(gamma,pi(0) pi(0)) and A(gamma, pi(0) pi(+) + pi(0) pi(-)) with A=H-1, C-12, and Pb-nat are presented. A significant. nuclear-mass dependence of the pipi invariant-mass distribution is found in the pi(0) pi(0) channel. The dependence is not observed in the pi(0) pi(+/-) channel. Within a unitary chiral-perturbation approach,(5)) the in-medium observation in the pi(0) pi(0) channel is interpreted as an in-medium modification of the pipi interaction in the sigma (I=J=0) channel, changing width and pole position with increasing effective nuclear density
Search for the semi-muonic charmonium decay J/ψ → D − μ +νμ + c.c.
No full textUsing (10087 ± 44) × 106 J/ψ events collected with the BESIII detector at the BEPCII e + e − storage ring at the center-of-mass energy of s = 3.097 GeV, we present a search for the rare semi-muonic charmonium decay J/ψ → D − μ + νμ + c.c. Since no significant signal is observed, we set an upper limit of the branching fraction to be B (J/ψ → D − μ + νμ + c.c.) < 5.6 × 10−7 at 90% confidence level. This is the first search for the weak decay of charmonium with a muon in the final state. [Figure not available: see fulltext.]. © 2024, The Author(s).<br/
Branching fraction measurement of J=Psi -> KSKL and search for J=Psi -> KSKS
No full textUsing a sample of 1.31 x 10(9) J/Psi events collected with the BESIII detector at the BEPCII collider, we study the decays of J/Psi -> KSKL and KSKS. The branching fraction of J/Psi -> KSKL is determined to be B(J/Psi -> KSKL) = (1.93 +/- 0.01 (stat) +/- 0.05 (syst)) x 10(-4), which significantly improves on previous measurements. No clear signal is observed for the J/Psi -> KSKS process, and the upper limit at the 95% confidence level for its branching fraction is determined to be B(J/Psi -> KSKS) < 1.4 x 10(-8), which improves on the previous searches by 2 orders in magnitude and reaches the order of the Einstein-Podolsky-Rosen expectation
Partial wave analysis of J/ψ →γηη′
No full textBased on a sample of (10.09±0.04)×109 J/ψ events collected with the BESIII detector operating at the BEPCII storage ring, a partial wave analysis of the decay J/ψ→γηη′ is performed. An isoscalar state with exotic quantum numbers JPC=1-+, denoted as η1(1855), has been observed for the first time with statistical significance larger than 19σ. Its mass and width are measured to be (1855±9-1+6) MeV/c2 and (188±18-8+3) MeV, respectively. The first uncertainties are statistical and the second are systematic. The product branching fraction B(J/ψ→γη1(1855))B(η1(1855)→ηη′) is measured to be (2.70±0.41-0.35+0.16)×10-6. In addition, an upper limit on the ratio of branching fractions B(f0(1710)→ηη′)/B(f0(1710)→ππ) is determined to be 1.61×10-3 at 90% confidence level, which lends support to the hypothesis that the f0(1710) has a large glueball component
Observation of h(1)(1380) in the J/psi -> eta ' K(K)over-bar pi decay
No full textUsing 1.31 x 10(9) J/psi events collected by the BESIII detector at the BEPCII e(+)e(-) collider, we report the first observation of the h(1)(1380) in J/psi -> eta'h(1)(1380) with a significance of more than ten standard deviations. The mass and width of the possible axial-vector strangeonium candidate h(1)(1380) are measured to be M = (1423.2 +/- 2.1 +/- 7.3) MeV/c(2) and Gamma = (90.3 +/- 9.8 +/- 17.5) MeV. The product branching fractions, assuming no interference, are determined to be B(J/psi -> eta'h(1)(1380)) x B(h(1)(1380) -> K*(892)K-+(-)+c.c.) = (1.51 +/- 0.09 +/- 0.21) x 10(-4) in eta'K+K-pi(0) mode and B(J/psi -> eta'h(1)(1380)) x B(h(1)(1380) -> K*(892)(K) over bar +c.c.) =(2.16 +/- 0.12 +/- 0.29) x 10(-4) in eta'(KSK +/-)-K-0 pi(-/+) mode. The first uncertainties are statistical and the second are systematic. Isospin symmetry violation is observed in the decays h(1)(1380) K*(892)K-+(-) + c.c. and h(1)(1380) -> K*(892)(0)(K) over bar (0) + c.c.. Based on the measured h(1)(1380) mass, the mixing angle between the states h(1)(1170) and h(1)(1380) is determined to be (35.9 +/- 2.6)degrees, consistent with theoretical expectations
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