34 research outputs found
Measurement of Born cross section of e + e − → Σ + Σ ¯ − at center-of-mass energies between 3.510 and 4.951 GeV
Using 24.1 fb−1 of e+e− collision data collected with the BESIII detector at the BEPCII collider, the Born cross sections and effective form factors of the e+e−→Σ+Σ¯− reaction are measured. The measurements are performed at center-of-mass energies ranging from 3.510 to 4.951 GeV. No significant evidence for the decay of the charmonium(-like) states, ψ(3770), ψ(4040), ψ(4160), Y(4230), Y(4360), ψ(4415), and Y(4660), into a Σ+Σ¯− final state is observed. Consequently, upper limits for the products of the branching fractions and the electronic partial widths at the 90% confidence level are reported for these decays
Measurement of the cross sections of e + e − → K − Ξ ¯ + Λ / Σ 0 at center-of-mass energies between 3. 510 and 4. 914 GeV
Using e+e− collision data collected with the BESIII detector at the BEPCII collider at center-of-mass energies between 3.510 and 4.914 GeV, corresponding to an integrated luminosity of 25 fb−1, we measure the Born cross sections for the process e+e−→K−Ξ¯+Λ/Σ0 at thirty-five energy points with a partial-reconstruction strategy. By fitting the dressed cross sections of e+e−→K−Ξ¯+Λ/Σ0, evidence for ψ4160→K−Ξ¯+Λ is found for the first time with a significance of 4.4σ, including systematic uncertainties. No evidence for other possible resonances is found. In addition, the products of electronic partial width and branching fraction for all assumed resonances decaying into K−Ξ¯+Λ/Σ0 are determined
Search for ∆S = 2 nonleptonic hyperon decays Ω − → Σ 0 π − and Ω − → nK −
Using (27.12 ± 0.14) × 108ψ(3686) events collected by the BESIII detector at the center-of-mass energy of s = 3.686 GeV, we search for the first time for two nonleptonic hyperon decays that change strangeness by two units, Ω− → Σ0π− and Ω− → nK−. No significant signal is observed. The upper limits on their decay branching fractions are determined to be B(Ω− → Σ0π−) < 5.4 × 10−4 and B(Ω− → nK−) < 2.4 × 10−4 at the 90% confidence level
Measurement of absolute branching fractions of D s + hadronic decays
Using e+e− collision data collected at the BESIII detector at center-of-mass energies between 4.128 and 4.226 GeV, corresponding to an integrated luminosity of 7.33 fb−1, we determine the absolute branching fractions of fifteen hadronic Ds+ decays with a double-tag technique. In particular, we make precise measurements of the branching fractions BDs+→K+K−π+=5.49±0.04±0.07%, BDs+→KS0K+=1.50±0.01±0.01% and BDs+→K+K−π+π0=5.50±0.05±0.11%, where the first uncertainties are statistical and the second ones are systematic. The CP asymmetries in these decays are also measured and all are found to be compatible with zero
Study of η ′ → π + π − l + l − decays at BESIII
With a sample of (10087 ± 44) × 106J/ψ events accumulated with the BESIII detector, we analyze the decays η′ → π+π−l+l−(l = e, μ) via the process J/ψ → γη′. The branching fractions are measured to be B(η′ → π+π−e+e−) = (2.45 ± 0.02(stat.) ± 0.08(syst.)) × 10−3 and B(η′ → π+π−μ+μ−) = (2.16 ± 0.12(stat.) ± 0.06(syst.)) × 10−5, and the ratio is Bη′→π+π−e+e−Bη′→π+π−μ+μ−=113.4±0.9stat.±3.7syst.. In addition, by combining the η′ → π+π−e+e− and η′ → π+π−μ+μ− decays, the slope parameter of the electromagnetic transition form factor is measured to be bη′ = 1.30 ± 0.19 (GeV/c2)−2, which is consistent with previous measurements from BESIII and theoretical predictions from the VMD model. The asymmetry in the angle between the π+π− and l+l− decay planes, which has the potential to reveal the CP-violation originating from an unconventional electric dipole transition, is also investigated. The asymmetry parameters are determined to be ACPη′→π+π−e+e−=−0.21±0.73stat.±0.01syst.% and ACPη′→π+π−μ+μ−=0.62±4.71stat.±0.08syst.%, implying that no evidence of CP-violation is observed at the present statistics. Finally, an axion-like particle is searched for via the decay η′ → π+π−a, a → e+e−, and upper limits of the branching fractions are presented for the mass assumptions of the axion-like particle in the range of 0 − 500 MeV/c2
Observation of ψ (3686) → Ω − K + Ξ ¯ 0 + c. c
Using (27.12 ± 0.14) × 108ψ(3686) events collected with the BESIII detector at BEPCII, the decay of ψ(3686) →Ω−K+Ξ¯0 + c.c. is observed for the first time. The branching fraction of this decay is measured to be Bψ3686→Ω−K+Ξ¯0+c.c. = (2.78 ± 0.40 ± 0.18) × 10−6, where the first uncertainty is statistical and the second is systematic. Possible baryon excited states are searched for in this decay, but no evident intermediate state is observed with the current sample size
Observation of the Singly Cabibbo-Suppressed Decay
The singly Cabibbo-suppressed decay is observed for the first time with a statistical
significance of by using 4.5 fb of collision data
collected at center-of-mass energies between 4.600 and 4.699 GeV with the
BESIII detector at BEPCII. The absolute branching fraction of
is measured to be in a model-independent approach. This is
the first observation of a Cabibbo-suppressed decay involving
in the final state. The ratio of branching fractions between
and the Cabibbo-favored decay
is calculated to be , where with the
Cabibbo mixing angle. This ratio significantly deviates from and
provides important information for the understanding of nonfactorization
contributions in decays.Comment: 8 pages, 2 figure
Study of the doubly Cabibbo-suppressed decays and
Based on 7.33 fb of 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 and are reported. We determine the
absolute branching fraction of to be
() . No
significant signal of is observed and the upper
limit on its decay branching fraction at 90\% confidence level is set to be
.Comment: 10 pages, 4 figures, 4 table
Updated measurements of the M1 transition with
Based on a data sample of events
collected with the BESIII detector at the BEPCII collider, the M1 transition
with is
studied, where is or
. The mass and width of the are
measured to be MeV/
and MeV, respectively. The
product branching fraction is determined to be . Using , we obtain the branching fraction of the
radiative transition to be , where the third uncertainty is due to the quoted
Partial Wave Analysis of
Using a sample of events collected with
the BESIII detector at the BEPCII collider, a partial wave analysis on the
decay is performed to investigate the intermediate
resonances in . The
resonances , , , ,
, , , , and
are observed with statistical significance greater than 5.
The product branching fractions are reported. The resonance parameters of
and are also measured