Using the CLEO-c detector at the Cornell Electron Storage Ring, we have measured inclusive and exclusive cross sections for the production of D+, D0 and Ds+ mesons in e+e- annihilations at thirteen center-of-mass energies between 3.97 and 4.26 GeV. Exclusive cross sections are presented for final states consisting of two charm mesons (DD, D*D, D*D*, Ds+Ds-, Ds*+Ds-, and Ds*+Ds*-) and for processes in which the charm-meson pair is accompanied by a pion. No enhancement in any final state is observed at the energy of the Y(4260).
We present an analysis of charm quark fragmentation at 10.6 GeV, based on a data sample of 103 fb collected by the Belle detector at the KEKB accelerator. We consider fragmentation into the main charmed hadron ground states, namely \DZ, \DP, \Ds and \LC, as well as the excited states \DSZ and \DSP. The fragmentation functions are important to measure as they describe processes at a low energy scale, where calculations in perturbation theory lead to large uncertainties. Fragmentation functions can also be used as input distributions for Monte Carlo generators. Additionally, we determine the ave…
Search for the Charmed Pentaquark Candidate Theta_c(3100) in e+e- Annihilations at sqrt(s)=10.58 GeV
我们在质心（c.m.）的e ^+ e ^-相互作用中寻找H1合作组报道的五夸克态候选者，即Theta_c（3100）^0。能量为10.58 GeV，使用SLAC的PEP-II e ^+ e ^-设施的BaBar探测器记录的124 fb-1数据。我们在H1所报道的相同pD ^{*-}衰变模式中没有发现这样一种状态的证据，我们对它的产生截面乘以pD ^{*-}的分支分数作为c. m的函数设定了限制。势头.对应于每个e ^+ e ^--> qqbar事件的总速率的极限，乘以分支分数，比在这些事件中测得的粲λ c和粲σ c重子的速率低大约三个数量级。
In this work, we generate gauge configurations with $N_f=2$ dynamical charm quarks on anisotropic lattices. The mass shift of $1S$ and $1P$ charmonia owing to the charm quark annihilation effect can be investigated directly in a manner of unitary theory. The distillation method is adopted to treat the charm quark annihilation diagrams at a very precise level. For $1S$ charmonia, the charm quark annihilation effect almost does not change the $J/ψ$ mass, but lifts the $η_c$ mass by approximately 3-4 MeV. For $1P$ charmonia, this effect results in positive mass shifts of approximately 1 MeV for $…
The exclusive Born cross sections of the production of $D^0$, $D^+$ and $D_s^+$ mesons in $e^+e^-$ annihilation at 13 energy points between 3.970 and 4.260 GeV are obtained by applying corrections for initial state radiation and vacuum polarization to the observed cross sections measured by CLEO-c experiment. Both the statistical and the systematic uncertainties for the obtained Born cross sections are properly estimated.
Measurement of tau polarization in e+ e- annihilation at sqrt{s}=58 GeV
利用TRISTAN电子对撞机，在质心能量为58 GeV的条件下，测量了反应e+ e-> tau+ tau-中τ轻子的极化。根据τ-> e nu nu bar、mu nu nu bar、rho nu和pi（K）nu衰变中子粒子的运动学分布，估算出τ-的平均极化及其前后不对称性分别为0.012 ± 0.058和0.029 ± 0.057。
Using the initial-state radiation method, the $e^+e^- \to K_S K_L$ cross section from 1.98 to 2.54 GeV is measured in a data sample of 469 fb$^{-1}$ collected with the BABAR detector. The results are used in conjunction with previous BABAR results for the $e^+e^- \to K^+ K^-$, $e^+e^- \to π^+π^-$, $e^+e^- \to π^+π^-η$, and $e^+e^- \to ωππ$ cross sections to investigate the nature of the resonance structure recently observed by the BESIII experiment in the $e^+e^- \to K^+ K^-$ cross section.
Up to now, the $N^*$ production from $e^+e^-$ annihilations has been studied only around charmonium region. Charmonium decays to $N^*$s are analogous to (time-like) EM form factors in that the charm quark annihilation provides a nearly pointlike (ggg) current. Complementary to other sources, such as $πN$, $eN$ and $γN$ reactions, this new source for $N^*$ spectroscopy has a few advantages, such as an isospin filter and a low spin filter. The experimental results on $N^*$ from $e^+e^-$ annihilations and their phenomenological implications are reviewed. Possible new sources on $N^*$ production f…
In this work, we present the mass spectrum of higher charomona around and above 4.6 GeV by adopting the unquenched potential model. We perform a combined fit to the updated experimental data of $e^+e^- \to ψ(2S)π^+π^-$ and $e^+e^-\to Λ_c\barΛ_c$. To understand the "platform" structure observed in the range of $4.57 \sim 4.60$ GeV existing in the $Λ_c\barΛ_c$ invariant mass spectrum of $e^+e^-\to Λ_c\barΛ_c$ of BESIII, we introduce two resonances in this combined fit to the $e^+e^- \to ψ(2S)π^+π^-$ and $e^+e^-\to Λ_c\barΛ_c$, which have resonance parameters, $m_{Y_1}=4585\pm2$ MeV, $Γ_{Y_1}=29.…
The results of the SERP-E-184 experiment at the U-70 accelerator (IHEP, Protvino) are presented. Interactions of the 70 GeV proton beam with carbon, silicon and lead targets were studied to detect decays of charmed $D^0$, $\bar D^0$, $D^+$, $D^-$ mesons and $Λ_c^+$ baryon near their production threshold. Measurements of lifetimes and masses have shown a good agreement with PDG data. The inclusive cross sections of charm production and their A-dependencies have been obtained. The yields of these particles are compared with the theoretical predictions and the data of other experiments. The measu…
