A search for invisible decays of the Lambda baryon is carried out in the process J/psi -> Lambda(Lambda) over bar based on (1.0087 +/- 0.0044) x 10(10) J/psi events collected with the BESIII ...detector located at the BEPCII storage ring. No signals are found for the invisible decays of. baryon, and the upper limit of the branching fraction is determined to be 7.4 x 10(-5) at the 90% confidence level. This is the first search for invisible decays of baryons; such searches will play an important role in constraining dark sector models related to the baryon asymmetry.
Using 2.93 fb −1 of e+e− collision data taken at a center-of-mass energy of 3.773 GeV with the BESIII detector, we report the first measurements of the absolute branching fractions of 14 hadronic ...D0(+) decays to exclusive final states with an η , e.g., D0 → K−π+η , K0Sπ0η , K+K−η , K0SK0Sη, K−π+π0η , K0Sπ+π−η , K0Sπ0π0η , and π+π−π0η ; D+ → K0Sπ+η,K0SK+η, K−π+π+η, K0Sπ+π0η, π+π+π−η , and π+π0π0η. Among these decays, the D0 → K−π+η and D+→K0Sπ+η decays have the largest branching fractions, which are B (D0 → K−π+η) = ( 1.853 ± 0.02 5 stat ± 0.03 1 syst ) % and B ( D+ → K0Sπ+η ) = ( 1.309 ± 0.03 7 stat ± 0.03 1 syst ) % , respectively. The charge-parity asymmetries for the six decays with highest event yields are determined, and no statistically significant charge-parity violation is found.
Based on a sample of
(
448.1
±
2.9
)
×
10
6
ψ
(
3686
)
events collected with the BESIII detector at BEPCII, the decays of
ψ
(
3686
)
→
K
−
Λ
Ξ
¯
+
+
c
.
c
.
with
Ξ
¯
+
→
Λ
¯
π
+
,
Λ
¯
→
p
¯
π
+
are ...studied. We investigate the two excited resonances,
Ξ
(
1690
)
−
and
Ξ
(
1820
)
−
, which are each observed with large significance (
≫
10
σ
) in the
K
−
Λ
invariant mass distributions. A partial wave analysis is performed, and the spin-parities of
Ξ
(
1690
)
−
and
Ξ
(
1820
)
−
are measured to be
1
2
−
and
3
2
−
, respectively. The masses, widths, and product branching fractions of
Ξ
(
1690
)
−
and
Ξ
(
1820
)
−
are also measured.
Published by the American Physical Society
2024
Observation of ψ ( 3770 ) → η J / ψ Achasov, M. N.; Ahmed, S.; Amoroso, A. ...
Physical review. D,
05/2023, Letnik:
107, Številka:
9
Journal Article
Recenzirano
Odprti dostop
Using a data sample collected with the BESIII detector operating at the BEPCII storage ring, the Born cross section of the process e+e- → ηJ/ψ at a center-of-mass energy s=3.773 GeV is measured to be ...( 8.88±0.87±0.42 ) pb . We fit the cross section line shape before correcting for the initial state radiation from s=3.773 to 4.600 GeV to obtain the branching fraction B ( ψ ( 3770 ) → ηJ/ψ ) . We obtain B ( ψ ( 3770 ) → ηJ/ψ ) = ( 11.3±5.9±1.1 ) ×10-4 when the ψ ( 3770 ) decay amplitude is added coherently to the other contributions, and ( 8.7±1.0±0.8 ) ×10-4 when it is added incoherently. Here the quoted uncertainties are statistical and systematic, respectively. In both cases, the statistical significance of ψ ( 3770 ) resonance is above 7σ . This is the first time the decay ψ ( 3770 ) → ηJ/ψ is observed with a statistical significance greater than 5σ .
Based on data samples collected with the BESIII detector at the BEPCII collider, the process e^{+}e^{-}→Σ^{+}Σover ¯^{-} is studied at center-of-mass energies sqrts=2.3960, 2.6454, and 2.9000 GeV. ...Using a fully differential angular description of the final state particles, both the relative magnitude and phase information of the Σ^{+} electromagnetic form factors in the timelike region are extracted. The relative phase between the electric and magnetic form factors is determined to be sinΔΦ=-0.67±0.29(stat)±0.18(syst) at sqrts=2.3960 GeV, ΔΦ=55°±19°(stat)±14°(syst) at sqrts=2.6454 GeV, and 78°±22°(stat)±9°(syst) at sqrts=2.9000 GeV. For the first time, the phase of the hyperon electromagnetic form factors is explored in a wide range of four-momentum transfer. The evolution of the phase along with four-momentum transfer is an important input for understanding its asymptotic behavior and the dynamics of baryons.
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