Abstract We report the first measurement of the absolute branching fraction of the inclusive decay $$\Lambda _c^+ \rightarrow K_S^0X$$ Λ c + → K S 0 X . The analysis is performed using an $$e^+e^-$$ ...e + e - collision data sample corresponding to an integrated luminosity of 567 $$\hbox {pb}^{-1}$$ pb - 1 taken at $$\sqrt{s}$$ s = 4.6 GeV with the BESIII detector. Using eleven Cabibbo-favored $${\bar{\Lambda }}_c^-$$ Λ ¯ c - decay modes and the double-tag technique, this absolute branching fraction is measured to be $${\mathcal {B}}(\Lambda _c^+ \rightarrow K_S^0X)=(9.9\pm 0.6\pm 0.4)\%$$ B ( Λ c + → K S 0 X ) = ( 9.9 ± 0.6 ± 0.4 ) % , where the first uncertainty is statistical and the second systematic. The relative deviation between the branching fractions for the inclusive decay and the observed exclusive decays is $$(18.7\pm 8.3)\%$$ ( 18.7 ± 8.3 ) % , which indicates that there may be some unobserved decay modes with a neutron or excited baryons in the final state.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Using 2.92 fb −1 of electron-positron annihilation data collected at a center-of-mass energy of √s=3.773 GeV with the BESIII detector, we present an improved measurement of the branching fraction ...B(D + → ωe + ν e )=(1.63±0.11±0.08)×10 −3 . The parameters defining the corresponding hadronic form factor ratios at zero momentum transfer are determined for the first time; we measure them to be r V =1.24±0.09±0.06 and r 2 =1.06±0.15±0.05. The first and second uncertainties are statistical and systematic, respectively. We also search for the decay D + → ϕe + ν e . An improved upper limit B(D + → ϕe + ν e )<1.3×10 −5 is set at 90% confidence level.
From December 2011 to May 2014, about 5 fb^-1 of data were taken with the BESIII detector at center-of- mass energies between 3.810 GeV and 4.600 GeV to study the charmonium-like states and higher ...excited charmonium states. The time-integrated luminosity of the collected data sample is measured to a precision of 1% by analyzing events produced by the large-angle Bhabha scattering process.
We measure the Born cross sections of the process e+e−→K+K−K+K− at center-of-mass (c.m.) energies, s, between 2.100 and 3.080 GeV. The data were collected using the BESIII detector at the BEPCII ...collider. An enhancement at s=2.232 GeV is observed, very close to the e+e−→ΛΛ¯ production threshold. A similar enhancement at the same c.m. energy is observed in the e+e−→ϕK+K− cross section. The energy dependence of the K+K−K+K− and ϕK+K− cross sections differs significantly from that of e+e−→ϕπ+π−.
Using a sample of (448.1±2.9)×106 ψ(3686) events collected with the BESIII detector, we perform the first partial wave analysis of ψ(3686)→K+K−η. In addition to the well established states, ϕ(1020), ...ϕ(1680), and K3*(1780), contributions from X(1750), ρ(2150), ρ3(2250), and K2*(1980) are also observed. The X(1750) state is determined to be a 1−− resonance. The simultaneous observation of the ϕ(1680) and X(1750) indicates that the X(1750), with previous observations in photoproduction, is distinct from the ϕ(1680). The masses, widths, branching fractions of ψ(3686)→K+K−η, and the intermediate resonances are also measured.
The charm semileptonic decays D+→ηe+νe and D+→η′e+νe are studied with a sample of e+e− collision data corresponding to an integrated luminosity of 2.93 fb−1 collected at s=3.773 GeV with the BESIII ...detector. We measure the branching fractions for D+→ηe+νe to be (10.74±0.81±0.51)×10−4, and for D+→η′e+νe to be (1.91±0.51±0.13)×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+νe. All the results are consistent with those obtained by the CLEO-c experiment.
Using a data sample of (1310.6 ± 7.0) × 106 J / ψ decay events collected with the BESIII detector at BEPCII, we study the electromagnetic Dalitz decay J / ψ → η′e+e− with two dominant η′ decay modes, ...η′ → γπ+π− and η′ → π+π−η. The branching fraction is determined to be B(J / ψ → η′e+e−) = (6.59 ± 0.07 ± 0.17) × 10−5, which improves in precision by a factor of 2 over the previous BESIII measurement. A search for the dark photon (γ′) is performed via J / ψ → η′γ′, γ′ → e+e−. Excluding the ω and ϕ mass regions, no significant signal is observed in the mass range from 0.1 to 2.1 GeV / c2. We set upper limits at the 90% confidence level on B(J / ψ → η′γ′) × B(γ′ → e+e−), B(J / ψ → η′γ′) and the mixing strength as a function of dark photon mass. This is among the first searches for dark photons in charmonium decays.
Abstract Using a sample of $$1.31\times 10^{9} ~J/\psi $$ 1.31×109J/ψ events collected with the BESIII detector, we perform a study of $$J/\psi \rightarrow \gamma K{\bar{K}}\eta '$$ J/ψ→γKK¯η′ . ...X(2370) is observed in the $$K{\bar{K}}\eta '$$ KK¯η′ invariant-mass distribution with a statistical significance of $$8.3\sigma $$ 8.3σ . Its resonance parameters are measured to be $$M=2341.6\pm 6.5 \, \text {(stat.)} \pm 5.7 \, \text {(syst.)}~ \hbox {MeV}/c^{2}$$ M=2341.6±6.5(stat.)±5.7(syst.)MeV/c2 and $$\Gamma = 117\pm 10 \, \text {(stat.)}\pm 8 \, \text {(syst.)}~\hbox {MeV}$$ Γ=117±10(stat.)±8(syst.)MeV . The product branching fractions for $$J/\psi \rightarrow \gamma X(2370),X(2370)\rightarrow K^{+}K^{-}\eta '$$ J/ψ→γX(2370),X(2370)→K+K-η′ and $$J/\psi \rightarrow \gamma X(2370),X(2370)\rightarrow K_{S}^{0}K_{S}^{0}\eta '$$ J/ψ→γX(2370),X(2370)→KS0KS0η′ are determined to be $$(1.79\pm 0.23\, \text {(stat.)}\pm 0.65\,\text {(syst.)})\times 10^{-5}$$ (1.79±0.23(stat.)±0.65(syst.))×10-5 and $$(1.18\pm 0.32\, \text {(stat.)}\pm 0.39\, \text {(syst.)})\times 10^{-5}$$ (1.18±0.32(stat.)±0.39(syst.))×10-5 , respectively. No evident signal for X(2120) is observed in the $$K{\bar{K}}\eta '$$ KK¯η′ invariant-mass distribution. The upper limits for the product branching fractions of $${\mathcal {B}}(J/\psi \rightarrow \gamma X(2120)\rightarrow \gamma K^{+} K^{-} \eta ')$$ B(J/ψ→γX(2120)→γK+K-η′) and $${\mathcal {B}}(J/\psi \rightarrow \gamma X(2120)\rightarrow \gamma K_{S}^{0} K_{S}^{0} \eta ')$$ B(J/ψ→γX(2120)→γKS0KS0η′) are determined to be $$1.49\times 10^{-5}$$ 1.49×10-5 and $$6.38\times 10^{-6}$$ 6.38×10-6 at the 90% confidence level, respectively.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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