© 2015 Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved. Juvenile myelomonocytic leukemia (JMML) is a myeloproliferative neoplasm (MPN) of childhood with a poor prognosis. Mutations in NF1, NRAS, KRAS, PTPN11 or CBL

We report a measurement of the branching fraction for ψ(3770)→γχc1 and search for the transition ψ(3770)→γχc2 based on 2.92 fb-1 of e+e- data accumulated at s=3.773 GeV with the BESIII detector at the BEPCII collider. We measure B(ψ(3770)→γχc1)=(2.48±0.15±0.23)×10-3, which is the most precise measurement to date. The upper limit on the branching fraction of ψ(3770)→γχc2 at a 90% confidence level is B(ψ(3770)→γχc2)<0.64×10-3. The corresponding partial widths are Γ(ψ(3770)→γχc1)=(67.5±4.1±6.7) keV and Γ(ψ(3770)→γχc2)<17.4 keV.

The process e+e−→ pp̄π0has been studied by analyzing data collected at (formula presented) GeV, at (formula presented) GeV, and during a ψ(3770) line shape scan with the BESIII detector at the BEPCII collider. The Born cross section of p̄pπ0in the vicinity of the ψ(3770) is measured, and the Born cross section of ψ(3770) → p̄pπ0is extracted considering interference between resonant and continuum production amplitudes. Two solutions with the same probability and a significance of 1.5 σ are found. The solutions for the Born cross section of ψ(3770) → p̄pπ0are 33.8 ± 1.8 ± 2.1 pb and (formula presented) pb (< 0.22 pb at a 90% confidence level). Using the estimated cross section and a constant decay amplitude approximation, the cross section σ(p̄p → ψ(3770)π0) is calculated for the kinematic situation of the planned P̄ANDA experiment. The maximum cross section corresponding to the two solutions is expected to be less than 0.79 nb at 90% confidence level and 122 ± 10 nb at a center-of-mass energy of 5.26 GeV.

We study the decays of the charmonium resonances J/ψ and ψ(3686) to the final states Ξ-Ξ+, Σ(1385) Σ(1385)± based on a single baryon tag method using data samples of (223.7±1.4)×106 J/ψ and (106.4±0.9)×106 ψ(3686) events collected with the BESIII detector at the BEPCII collider. The decay ψ(3686)→Σ(1385) Σ(1385)± is observed for the first time, and the measurements of the other processes, including the branching fractions and angular distributions, are in good agreement with, and much more precise than, the previously published results. Additionally, the ratios B(ψ(3686)→Ξ-Ξ+)B(J/ψ→Ξ-Ξ+), B(ψ(3686)→Σ(1385)-Σ(1385)+)B(J/ψ→Σ(1385)-Σ(1385)+) and B(ψ(3686)→Σ(1385)+Σ(1385)-)B(J/ψ→Σ(1385)+Σ(1385)-) are determined.

We study D0D̅0 pairs produced in e+e− collisions at √ s = 3.773 GeVusing a data sample of 2.92 fb−1 collected with the BESIII detector. We measuredthe asymmetry ACPKπ of the branching fractions of D → K−π+ in CP-odd and CP-even eigenstates to be (12.7 ± 1.3 ± 0.7) × 10−2. ACPKπ can be used to extract the strong phase difference δKπ between the doubly Cabibbo-suppressed process D̅0 → K−π+ and the Cabibbo-favored process D0 → K−π+. Using world-average values of external parameters, we obtain cos δKπ = 1.02 ±0.11 ±0.06 ±0.01. Here, the first and second uncertainties are statistical and systematic, respectively, while the third uncertainty arises from the external parameters. This is the most precise measurement of δKπ to date.

Based on (106.41±0.86)×106 ψ(3686) events collected with the BESIII detector at the BEPCII collider, the branching fractions of ψ(3686)→π+π-J/ψ, J/ψ→e+e-, and J/ψ→μ+μ- are measured. We obtain B[ψ(3686)→π+π-J/ψ]=(34.98±0.02±0.45)%, B[J/ψ→e+e-]=(5.983±0.007±0.037)%, and B[J/ψ→μ+μ-]=(5.973±0.007±0.038)%. The measurement of B[ψ(3686)→π+π-J/ψ] confirms the CLEO-c measurement, and is apparently larger than the others. The measured J/ψ leptonic decay branching fractions agree with previous experiments within one standard deviation. These results lead to B[J/ψ→l+l-]=(5.978±0.005±0.040)% by averaging over the e+e- and μ+μ- channels and a ratio of B[J/ψ→e+e-]/B[J/ψ→μ+μ-]=1.0017±0.0017±0.0033, which tests e-μ universality at the four tenths of a percent level. All the measurements presented in this paper are the most precise in the world to date.

Using a sample of 1.3 × 10(9)  J/ψ events collected with the BESIII detector, we report the first observation of η(')→π(+)π(-)π(+)π(-) and η(')→π(+)π(-)π(0)π(0). The measured branching fractions are B(η(')→π(+)π(-)π(+)π(-)) = [8.53 ± 0.69(stat.) ± 0.64(syst.)]×10(-5) and B(η(')→π(+)π(-)π(0) π(0)) = [1.82 ± 0.35(stat.) ± 0.18(syst.)] × 10(-4), which are consistent with theoretical predictions based on a combination of chiral perturbation theory and vector-meson dominance.

Using 2.92 fb-1 of electron-positron annihilation data collected at √s = 3.773 GeV with the BESIII detector, we report the results of a search for the flavor-changing neutral current process D0 →γγ using a double-tag technique. We find no signal and set an upper limit at 90% confidence level for the branching fraction of B(D0 →γγ)< 3.8 × 10-6. We also investigate D0-meson decay into two neutral pions, obtaining a branching fraction of B(D0 →π0π0)= (8.24 ± 0.21(stat) ± 0.30(syst)) × 10-4, the most precise measurement to date and consistent with the current world average.

We study the process e+ e- →(D* D*)± π∓ at a center-of-mass energy of 4.26 GeV using a 827  pb(-1) data sample obtained with the BESIII detector at the Beijing Electron Positron Collider. Based on a partial reconstruction technique, the Born cross section is measured to be (137±9±15)  pb. We observe a structure near the (D* D*)± threshold in the π∓ recoil mass spectrum, which we denote as the Zc±(4025). The measured mass and width of the structure are (4026.3±2.6±3.7)  MeV/c2 and (24.8±5.6±7.7)  MeV, respectively. Its production ratio σ(e+ e- → Zc±(4025)π∓ → (D* D*)± π∓)/σ(e+ e- → (D* D*)± π∓) is determined to be 0.65±0.09±0.06. The first uncertainties are statistical and the second are systematic.

Using 1.06 × 108ψ (3686) events recorded in e+e-, collisions at √s = 3.686 GeV with the BESIII at the BEPCII collider, we present searches for C-parity violation in J/ψ → γγ and γφ decays via ψ(3686) → J/ψπ+π-. No significant signals are observed in either channel. Upper limits on the branching fractions are set to be B(J/ψ → γγ) < 2.7 × 10-7, and B(J/ψ → γφ>) < 1.4 × 10-6, at the 90% confidence level. The former is one order of magnitude more stringent than the previous upper limit, and the latter represents the first limit on this decay channel.