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Fang, X.

Publications and source records attributed to Fang, X..

At least 55 records · Page 3
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DOE OSTI2018

Study of the decays D + → η ( ' ) e + ν e

The charm semileptonic decays D + → ηe + v e and D + → η'e+v e are studied with a sample of e + e - collision data corresponding to an integrated luminosity of 2.93 fb -1 collected at $ \sqrt{s}=3.773 $ GeV with the BESIII detector. We measure the branching fractions for D+ → ηe+v e to be (10.74 ± 0.81 ± 0.51) x 10 -4 , and for D+ → → η'e+v e to be (1.91 ± 0.51 ± 0.13) x 10 -4 , where the uncertainties are statistical and systematic, respectively. In addition, we perform a measurement of the form factor in the decay D+ → ηe+v e . All the results are consistent with those obtained by the CLEO-c experiment.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2018

Reaction rate for carbon burning in massive stars

Carbon burning is a critical phase for nucleosynthesis in massive stars. The conditions for igniting this burning stage, and the subsequent isotope composition of the resulting ashes, depend strongly on the reaction rate for 12 C+ 12 C fusion at very low energies. Results for the cross sections for this reaction are influenced by various backgrounds encountered in measurements at such energies. In this paper, we report on a new measurement of 12 C+ 12 C fusion cross sections where these backgrounds have been minimized. In conclusion, it is found that the astrophysical S factor exhibits a maximum around E cm =3.5–4.0 MeV, which leads to a reduction of the previously predicted astrophysical reaction rate.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Search for ψ ( 3686 ) → γ η c ( η ( 1405 ) ) → γ π + π - π 0

Using a sample of 448.1×10 6 ψ(3686) events collected with the BESIII detector, a search for the isospin violating decay η c → π⁺π⁻π⁰ via ψ(3686) → γ η c is presented. No signal is observed, and the upper limit on B(ψ(3686) → γ η c ) × B( η c → π⁺π⁻π⁰) is determined to be 1.6 × 10 -6 at the 90% confidence level. In addition, a search for η (1405) → f 0 (980)π 0 in (3686) radiative decays is performed. No signal is observed, and the branching fraction B(ψ(3686) → γη(1405))×B( η (1405) → f 0 (980)π 0 ) × B(f 0 (980) → π⁺π⁻ is calculated to be less than 5.0 × 10 -7 at the 90% confidence level.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Branching fraction measurement of J / ψ → K S K L and search for J / ψ → K S K S

Using a sample of 1.31×10 9 J/ψ events collected with the BESIII detector at the BEPCII collider, we study the decays of J/ψ→ K S K L and K S K S . The branching fraction of J/ψ→ K S K L is determined to be B(J/ψ→ K S K L ) = (1:93 0:01 (stat:) 0:05 (syst:))×10 -4 , which signi cantly improves on previous measurements. No clear signal is observed for the J/ψ→ K S K S process, and the upper limit at the 95% con dence level for its branching fraction is determined to be B(J= ! K S K S ) < 1:4×10 -8 , which improves on the previous searches by 2 orders in magnitude and reaches the order of the Einstein-Podolsky-Rosen expectation.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗