Search

By analyzing an e(+)e(-) data sample corresponding to an integrated luminosity of 2.93 fb(-1) taken at a centerof- mass energy of 3.773 GeV with the BESIII detector, we measure the branching fractions of the Cabibbofavored hadronic decays D-0 -> K- pi' eta', D-0 -> K-s(0)pi(0)eta', which are determined to be (6.43 +/- 0.15(stat)+/- 0.31(syst)) x 10(-3), (2.52 +/- 0.22(stat) +/- 0.15(syst)) x 10(-3,) and (1.90 +/- 0.17(stat) +/- 0.13(syst)) x 10(-3), respectively. The precision of the branching fraction of D-0 -> K- pi(+) eta' is significantly improved, and the processes D-0 -> K-S(0)pi(0)eta' and D+ -> K-S(0) pi(+)eta' are observed for the first time.

Based on a data sample of (448.1 +/- 2.9) x 10(6)Psi(3686) decays collected with the BESIII experiment, a search for the flavor changing neutral current transition Psi(3686) -> Lambda(+)(c) pe(+) e(-) + c.c. is performed for the first time. No signal candidates are observed and the upper limit on the branching fraction of Psi(3686) -> Lambda(+)(c) pe(+) e(-) is determined to be 1.7 x 10(-6) at the 90% confidence level. The result is consistent with expectations from the standard model, and no evidence for new physics is found.

The process e(+)e(-) -> D*D-+(s)*(s0) (2317)(-) + c.c. is observed for the first time with the data sample of 567 pb(-1) collected with the BESIII detector operating at the BEPCII collider at a center-of-mass energy root s = 4.6 GeV. The statistical significance of the D*(s0) (2317)(+/-) signal is 5.8 sigma and the mass is measured to be (2318.3 +/- 1.2 +/- 1.2) MeV/c(2). The absolute branching fraction B(D*(s0) (2317)(+/-) -> pi D-0(s)+/-) is measured as 1.00(-0.14)(+0.00) (stat)(-0.14)(+0.00) (syst) for the first time. The uncertainties are statistical and systematic, respectively.

Using a sample of 448.1 x 10(6) psi(3686) events collected with the BESIII detector, a search for the isospin violating decay eta(c) -> pi(+) pi(-) pi(0) via psi(3686) -> gamma eta(c) is presented. No signal is observed, and the upper limit on B(psi(3686) -> gamma eta(c)) x B(eta(c) -> pi(+) pi(-) pi(0)) is determined to be 1.6 x 10(-6) at the 90% confidence level. In addition, a search for eta(1405) -> f(0) (980) pi(0) in psi(3686) radiative decays is performed. No signal is observed, and the branching fraction B(psi(3686) -> gamma eta(1405)) x B(eta(1405) -> f(0)(980)pi(0)) x B(f(0)(980) -> pi(+)pi(-)) is calculated to be less than 5.0 x 10(-7) at the 90% confidence level.

Using a sample of 1.31 x 10(9) J/Psi events collected with the BESIII detector at the BEPCII collider, we study the decays of J/Psi -> KSKL and KSKS. The branching fraction of J/Psi -> KSKL is determined to be B(J/Psi -> KSKL) = (1.93 +/- 0.01 (stat) +/- 0.05 (syst)) x 10(-4), which significantly improves on previous measurements. No clear signal is observed for the J/Psi -> KSKS process, and the upper limit at the 95% confidence level for its branching fraction is determined to be B(J/Psi -> KSKS) < 1.4 x 10(-8), which improves on the previous searches by 2 orders in magnitude and reaches the order of the Einstein-Podolsky-Rosen expectation.

Using a data set with an integrated luminosity of $2.93\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ collected at $\sqrt{s}=3.773\text{ }\mathrm{GeV}$ with the BESIII detector operating at the BEPCII storage rings, we search for the rare decay ${D}^{+}\ensuremath{\rightarrow}{D}^{0}{e}^{+}{\ensuremath{\nu}}_{e}$. No signal events are observed. We set the upper limit on the branching fraction for ${D}^{+}\ensuremath{\rightarrow}{D}^{0}{e}^{+}{\ensuremath{\nu}}_{e}$ to be $1.0\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}4}$ at the 90% confidence level.

Pontecorvo reactions are antiproton annihilations on nuclei in which the final states are of a type not attainable from annihilations on free nucleons, for example pd→Xn, where X is a single meson. We report on the first observations of Pontecorvo reactions with a recoiling neutron, from p annihilation at rest in liquid deuterium. The results are B.R.(pd→π0n)=(6.63±0.59)×10−6, B.R.(pd→ηn)=(2.99±0.42)×10−6, B.R.(pd→ωn)=(21.2×3.5)×10−6, and B.R.(pd→η′n) ≤12×10−6 (at 90% C.L.). The result for pd→π0n is compatible with the only previously observed Pontecorvo reaction pd→π−p, assuming charge independence. The ratios of these branching ratios are compared to predictions based on dynamical models of the annihilation process which reproduce the general features of the data.

The Crystal Barrel detector at LEAR was used to study pp annihilation at rest into the final state ωηπ0, where the final‐state mesons were observed in all‐neutral decay modes. A sample of 10.9×104 ωηπ0 events was obtained from the analysis of 106 annihilations into all‐neutral final states. An amplitude analysis of the Dalitz plot shows that the final state is dominated by production of the a0(980), along with contributions from the a2(1320) and the b1(1235). No additional contributions were required to fit the Dalitz plot, and upper limits for the production of vector and axial‐vector particles decaying to ηπ0 were determined.