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Register a new userMeasurement of $mathcal B(psi(3770)togamma chi_{c1})$ and search for $psi(3770)togamma chi_{c2}$
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We report a measurement of the branching fraction of $psi(3770)togammachi_{c1}$ and search for the transition $psi(3770)rightarrow gamma chi_{c2}$ based on 2.92~fb$^{-1}$ of $e^+e^-$ data accumulated at $sqrt{s}=3.773$~GeV with the BESIII detector at the BEPCII collider. The measured branching fraction of $psi(3770) rightarrow gamma chi_{c1}$ is $mathcal B(psi(3770) rightarrow gamma chi_{c1})=(2.48 pm 0.15 pm 0.23) times 10^{-3}$, which is the most precise measurement to date. The upper limit on the branching fraction of $psi(3770)rightarrow gamma chi_{c2}$ at a $90%$ confidence level is $mathcal B(psi(3770) rightarrow gamma chi_{c2})<0.64 times 10^{-3}$. The corresponding partial widths are $Gamma(psi(3770) to gamma chi_{c1}) =(67.5pm 4.1pm 6.7)$~keV and $Gamma(psi(3770) to gamma chi_{c2}) < 17.4$~keV.
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From e+e- collision data acquired with the CLEO detector at CESR, we observe the non-D Dbar decay psi(3770)->gamma chi_c1 with a statistical significance of 6.6 standard deviations, using the two-photon cascades to J/psi and J/psi->l+l-. We determine sigma(e+e- -> psi(3770)) x BR(psi(3770)->gamma chi_c1) =(18.0 pm3.3 pm2.5) pb and branching fraction BR(psi(3770)->gamma chi_c1)=(2.8+-0.5+-0.4) x 10^-3. We set 90% C.L. upper limits for the transition to chi_c2 (chi_c0) : sigma x BR < 5.7 pb (< 282 pb) and BR < 0.9 x 10^-3 (<44 x 10^-3). We also determine Gamma(psi(3770)->gamma chi_c1)/Gamma(psi(3770)->pi+pi-J/psi) =1.5+-0.3+-0.3 (>1.0 at 90 % C.L.), which bears upon the interpretation of X(3872).
Using 106~million $psi(3686)$ events collected with the BESIII detector, we measure multipole amplitudes for the decay $psi(3686)rightarrowgammachi_{c1,2}togammagamma J/psi$ beyond the dominant electric-dipole amplitudes. The normalized magnetic-quadrupole amplitude for $psi(3686)rightarrowgammachi_{c1,2}rightarrowgammagamma J/psi$ and the normalized electric-octupole amplitudes for $psi(3686)rightarrowgammachi_{c2}$,~$chi_{c2}rightarrowgamma J/psi$ are determined. The M2 amplitudes for $psi(3686)rightarrowgammachi_{c1}$ and $chi_{c1,2}rightarrowgamma J/psi$ are found to differ significantly from zero and are consistent with theoretical predictions. We also obtain the ratios of M2 contributions of $psi(3686)$ and $J/psi$ decays to $chi_{c1,2}$, $b_{2}^{1}/b_{2}^{2} = 1.35pm0.72$ and $a_{2}^{1}/a_{2}^{2} = 0.617pm0.083$, which agree well with theoretical expectations. By considering the multipole contributions of $chi_{c1,2}$, we measure the product branching fractions for the cascade decays $psi(3686)rightarrowgammachi_{c0,1,2}togammagamma J/psi$ and search for the process $eta_{c}(2S)togamma J/psi$ through $psi(3686)rightarrowgammaeta_{c}(2S)$. The product branching fraction for $psi(3686)rightarrowgammachi_{c0}togammagamma J/psi$ is 3$sigma$ larger than published measurements, while those of $psi(3686)rightarrowgammachi_{c1,2}togammagamma J/psi$ are consistent. No significant signal for the decay $psi(3686)togamma eta_c(2S)togamma gamma J/psi$ is observed, and the upper limit of the product branching fraction at the 90% confidence level is determined.
We report the final results of a study of the psi(3770) meson using a data sample collected with the KEDR detector at the VEPP-4M electron-positron collider. The data analysis takes into account the interference between the resonant and nonresonant $Dbar{D}$ production, where the latter is related to the nonresonant part of the energy-dependent form factor $F_D$. The vector dominance approach and several empirical parameterizations have been tried for the nonresonant $F_D^{NR}(s)$. Our results for the mass and total width of psi(3770) are M = 3779.2 ^{+1.8}_{-1.7} ^{+0.5}_{-0.7} ^{+0.3}_{-0.3} MeV, Gamma =24.9 ^{+4.6}_{-4.0} ^{+0.5}_{-0.6} ^{+0.2}_{-0.9} MeV, where the first, second and third uncertainties are statistical, systematic and model, respectively. For the electron partial width two possible solutions have been found: (1) Gamma_{ee} = 154 ^{+79}_{-58} ^{+17}_{-9} ^{+13}_{-25} eV, (2) Gamma_{ee} = 414 ^{+72}_{-80} ^{+24}_{-26} ^{+90}_{-10} eV. Our statistics are insufficient to prefer one solution to another. The solution (2) mitigates the problem of non-$Dbar{D}$ decays but is disfavored by potential models. It is shown that taking into account the resonance--continuum interference in the near-threshold region affects resonance parameters, thus the results presented can not be directly compared with the corresponding PDG values obtained ignoring this effect.
By analyzing data samples of 2.9 fb^{-1} collected at sqrt s=3.773 GeV, 482 pb^{-1} collected at sqrt s=4.009 GeV and 67 pb^{-1} collected at sqrt s=3.542, 3.554, 3.561, 3.600 and 3.650 GeV with the BESIII detector at the BEPCII storage ring, we search for psi(3770) and psi(4040) decay to baryonic final states, including LambdabarLambdapi^+pi^-, Lambda barLambdapi^0, LambdabarLambdaeta, Sigma^+ barSigma^-, Sigma^0 barSigma^0, Xi^-barXi^+ and Xi^0barXi^0 decays. None are observed, and upper limits are set at the 90% confidence level.
We report the first observation of the decay B+ -> psi(3770) K+ where psi(3770) is reconstructed in the D0D0-bar and D+D- decay channels. The obtained branching fraction is Br(B+ -> psi(3770) K+)=(0.48+-0.11+-0.07)x10^{-3}. We have measured the branching fraction for the decay B+ -> D0D0-bar K+ to be (1.17+-0.21+-0.15)x10^{-3}. We have set a 90% confidence level upper limit of 0.90x10^{-3} for the decay B+ -> D+D-K+. We also present the results of a search for possible decays to DD-bar and D0D0-bar pi0 of the recently observed X(3872) particle. The analysis is based on 88 fb^{-1} of data collected at the Upsilon(4S) resonance by the Belle detector at the KEKB asymmetric-energy e+e- collider.
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