اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدObservation of a near-threshold enhancement in the $Lambdabar{Lambda}$ mass spectrum from $e^+e^-tophiLambdabar{Lambda}$ at $sqrt{s}$ from 3.51 to 4.60 GeV
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The process $e^+ e^- to phi Lambda bar{Lambda}$ is studied using data samples collected with the BESIII detector at the BEPCII collider at center-of-mass energies $sqrt{s}$ ranging from $3.51$ to $4.60~{rm GeV}$ . An intermediate resonance structure is observed near the threshold of $Lambda bar{Lambda}$. It has a mass of $(2262 pm 4 pm 28)~{rm{MeV}}/c^{2}$ and a width of $(72 pm 5 pm 43)~rm{MeV}$, where the quoted uncertainties are statistical and systematic, respectively. The $J^{PC}$ quantum numbers of $0^{-+}$ and $0^{++}$ are rejected, while other $J^{PC}$ hypotheses are possible, according to the helicity angle study. The energy-dependent cross section of the $e^+ e^- to phi Lambda bar{Lambda}$ process is measured for the first time in this energy region, and contributions from excited $psi$ states and vector charmonium-like $Y$-states are investigated.
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The process $e^{+}e^{-}rightarrowLambdabar{Lambda}$ is studied using data samples at $sqrt{s}=2.2324$, 2.400, 2.800 and 3.080 GeV collected with the BESIII detector operating at the BEPCII collider. The Born cross section is measured at $sqrt{s}$=2.2
324 GeV, which is 1.0 MeV above the $Lambdabar{Lambda}$ mass threshold, to be $305pm45^{+66}_{-36}$ pb, where the first uncertainty is statistical and the second systematic. The substantial cross section near threshold is significantly larger than that expected from theory, which predicts the cross section to vanish at threshold. The Born cross sections at $sqrt{s}$=2.400, 2.800 and 3.080 GeV are measured and found to be consistent with previous experimental results, but with improved precision. Finally, the corresponding effective electromagnetic form factors of $Lambda$ are deduced.
Unexpected features of the BaBar data on e+e- in baryon-antibaryon cross sections are discussed. These data have been collected, with unprecedented accuracy, by means of the initial state radiation technique, which is particularly suitable in giving
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The near-threshold $e^+e^- to Lambdabar{Lambda}$ reaction is studied with the assumption that the production mechanism is due to a near-$Lambda bar{Lambda}$-threshold resonance. The cross section of $e^+e^- to Lambdabar{Lambda}$ reaction is parametri
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The process $e^{+}e^{-} to phi eta^{prime}$ has been studied for the first time in detail using data sample collected with the BESIII detector at the BEPCII collider at center of mass energies from 2.05 to 3.08 GeV. A resonance with quantum numbers $
J^{PC}=1^{--}$ is observed with mass $M$ = (2177.5 $pm$ 4.8 (stat) $pm$ 19.5 (syst)) MeV/${ it{c}^{mathrm{2}}}$ and width $Gamma$ = (149.0 $pm$ 15.6 (stat) $pm$ 8.9 (syst)) MeV with a statistical significance larger than 10$sigma$. The observed structure could be identified with the $phi(2170)$, then the ratio of partial width between the $phi eta^{prime}$ by BESIII and $phi eta$ by BABAR is ($mathcal{B}^{R}_{phi eta}Gamma^{R}_{ee})/{(mathcal{B}^{R}_{phi eta^{prime}}Gamma^{R}_{ee})}$ = 0.23 $pm$ 0.10 (stat) $pm$ 0.18 (syst), which is smaller than the prediction of the $sbar{s}g$ hybrid models by several orders of magnitude.
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