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Register a new userPartial wave analysis of $J/psi to gamma eta eta$
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Based on a sample of $2.25times 10^{8}$ $J/psi$ events collected with the BESIII detector at BEPCII, a full partial wave analysis on $J/psitogammaetaeta$ was performed using the relativistic covariant tensor amplitude method. The results show that the dominant $0^{++}$ and $2^{++}$ components are from the $f_0(1710)$, $f_0(2100)$, $f_0(1500)$, $f_2(1525)$, $f_2(1810)$ and $f_2(2340)$. The resonance parameters and branching fractions are also presented.
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Using a sample of $1.06 times 10^{8}$ $psi(2S)$ events collected with the BESIII detector at BEPCII, the decay $psi(2S) to p bar{p}eta$ is studied. A partial wave analysis determines that the intermediate state N(1535) with a mass of $1524pm5^{+10}_{-4}$ MeV/$c^2$ and a width of $130^{+27+57}_{-24-10}$ MeV/$c^2$ is dominant in the decay; the product branching fraction is determined to be $B(psi(2S) to N(1535)bar{p})times B(N(1535)to peta)+c.c. = (5.2pm0.3^{+3.2}_{-1.2})times 10^{-5}$. Furthermore, the branching fraction of $psi(2S) to eta p bar{p}$ is measured to be $(6.4pm0.2pm0.6)times 10^{-5}$.
Using $5.8 times 10^7 J/psi$ events collected in the BESII detector, the radiative decay $J/psi to gamma phi phi to gamma K^+ K^- K^0_S K^0_L$ is studied. The $phiphi$ invariant mass distribution exhibits a near-threshold enhancement that peaks around 2.24 GeV/$c^{2}$. A partial wave analysis shows that the structure is dominated by a $0^{-+}$ state ($eta(2225)$) with a mass of $2.24^{+0.03}_{-0.02}{}^{+0.03}_{-0.02}$ GeV/$c^{2}$ and a width of $0.19 pm 0.03^{+0.06}_{-0.04}$ GeV/$c^{2}$. The product branching fraction is: $Br(J/psi to gamma eta(2225))cdot Br(eta(2225)to phiphi) = (4.4 pm 0.4 pm 0.8)times 10^{-4}$.
Using a sample of $(448.1pm2.9)times10^6$ $psi(3686)$ events collected with the BESIII detector, we perform the first partial wave analysis of $psi(3686)rightarrow K^+K^-eta$. In addition to the well established states, $phi(1020)$, $phi(1680)$, and $K_3^*(1780)$, contributions from $X(1750)$, $rho(2150)$, $rho_3(2250)$, and $K^*_2(1980)$ are also observed. The $X(1750)$ state is determined to be a $1^{--}$ resonance. The simultaneous observation of the $phi(1680)$ and $X(1750)$ indicates that the $X(1750)$, with previous observations in photoproduction, is distinct from the $phi(1680)$. The masses, widths, branching fractions of $psi(3686)rightarrow K^+K^-eta$ and the intermediate resonances are also measured.
A partial wave analysis of pbar-p -> eta-eta-pizero data from the Crystal Barrel experiment is made in terms of s-channel resonances. The decay channels a_0(980)-eta, f_0(1770)-pi and f_0(2105)-pi provide evidence for two I = 1 J^{PC} = 0^{-+} resonances. The first has mass M =2360 +- 25 MeV and width Gamma = 300^{+100}_{-50} MeV, and the second M =2070 pm 35 MeV, Gamma = 310^{+100}_{-50} MeV. There is also evidence for a J^{PC} = 2^{-+} state with M = 2005 +- 15 MeV and Gamma = 200 +- 40 MeV, decaying strongly to a_0(980)-pi.
We measure the mass of the eta meson using psi(2S) --> eta J/psi events acquired with the CLEO-c detector operating at the CESR e+e- collider. Using the four decay modes eta --> gamma gamma, 3pi0, pi+pi-pi0, and pi+pi-gamma, we find M(eta)=547.785 +- 0.017 +- 0.057 MeV, in which the first uncertainty is statistical and the second systematic. This result has an uncertainty comparable to the two most precise previous measurements and is consistent with that of NA48, but is inconsistent at the level of 6.5sigma with the much smaller mass obtained by GEM.
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