Using the CLEO-c detector at the Cornell Electron Storage Ring, we have measured inclusive and exclusive cross sections for the production of $D^+$, $D^0$ and $D_s^+$ 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 charmed mesons ($D\bar{D}$, $D^{*}\bar{D}$, $D^{*}\bar{D}^{*}$, $D_s^+ D_s^-$, $D_s^{*+} D_s^-$, and $D_s^{*+} D_s^{*-}$) and for processes in which the charmed meson pair is accompanied by a pion.
We report BELLE measurements of the exclusive cross sections for the processes e+e-->DD*, e+e-->DD, e+e-->DDpi, the first observation of psi(4415)-> DD*2(2460)bar decay and new state, Y(4660), using ISR. In addition, another cluster of events at around 4.05GeV/c2 is reported.
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 $…
E835 at FNAL: Charmonium Spectroscopy in $\bar p p$ Annihilations
我目前的初步结果，在其$η_cγ$和$J/ψπ^0$衰变模式的$h_c$搜索。我们观察到过量的η_cγ $ events near 3526 MeV that has a probability $ { \cal P} \sim 0.001 $ to arise from background fluctations. The resonance parameters are $ M=3525.8 \pm 0.2 \pm 0.2 $MeV, $ Γ \leq $ 1 MeV, and $ 10.6 \pm 3.7 \pm 3.4（br）< Γ_{ \bar{p} p} B_{η_cγ} < 12.8 \pm 4.8 \pm 4.5（br）$eV. We find no event excess within the search region in the $ J/π^0$模式。
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.
The $1^1D_2 (c\bar c)$ state is the ground state of spin-singlet D-wave charmonia. Although it has not been found yet, the experimental data accumulate rapidly. This charmonium attracts more and more attention, especially when the BaBar Collaboration finds that the X(3872) particle has negative parity. In this paper we calculate the double-gamma and double-gluon annihilation processes of $^1D_2$ charmonia and bottomonia by using the instantaneous Bethe-Salpeter method. We find the relativistic corrections make the decay widths of $1^1D_2 (c\bar c)$ 2$\sim$5 times smaller than the non-relativis…
In this paper, in order to probe the spectator-scattering and weak annihilation contributions in charmless $B_s\to VV$ (where $V$ stands for a light vector meson) decays, we perform the $χ^2$-analyses for the end-point parameters within the QCD factorization framework, under the constraints from the measured $\bar B_{s}\to$$ρ^0ϕ$, $ϕK^{*0}$, $ϕϕ$ and $K^{*0}\bar K^{*0}$ decays. The fitted results indicate that the end-point parameters in the factorizable and nonfactorizable annihilation topologies are non-universal, which is also favored by the charmless $B\to PP$ and $PV$ (where $P$ stands fo…
The charm production is sensitive to early dynamics of the created system in RHIC heavy ion collisions. Dominant process of charm quarks production at RHIC is believed to be initial gluon fusion which can be calculated in the perturbative QCD. Understanding both the charm production total cross section and the fragmentation in p+p collisions is a baseline to further exploring the QCD medium via open charm and charmonium in heavy ion collisions. In this paper we present the first reconstruction of open charm meson $D^{0}$ via the weak decay to K and $π$ mesons in the p+p collisions at $\sqrt{s}…
We search for signals of Weak Annihilation in inclusive semileptonic D decays. We consider both the widths and the lepton energy moments, which are quite sensitive probes. Our analysis of Cleo data shows no clear evidence of Weak Annihilation, and allows us to put bounds on their relevance in charmless B semileptonic decays.
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.…
In this article, we report on the STAR results of open charm hadron production at mid-rapidity in $p+p$ and Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV and $p+p$ collisions at $\sqrt{s}$ = 500 GeV. The measurements cover transverse momentum range from 0.6 to 6 GeV/c for $p+p$ 200 GeV collisions, from 1 to 6 GeV/c for $p+p$ 500 GeV collisions and from 0 to 6 GeV/c for Au+Au 200 GeV collisions. $D^0$ nuclear modification factor and elliptic flow in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV are presented.
