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Register a new userObservation of $psi(3686) to p bar{p} eta^{prime}$ and improved measurement of $J/psi to p bar{p} eta^{prime}$
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We observe the process $psi(3686) to p bar{p} eta^{prime}$ for the first time, with a statistical significance higher than 10$sigma$, and measure the branching fraction of $J/psi to p bar{p} eta^{prime}$ with an improved accuracy compared to earlier studies. The measurements are based on $4.48 times 10^8$ $psi(3686)$ and $1.31 times 10^{9}$ $J/psi$ events collected by the BESIII detector operating at the BEPCII. The branching fractions are determined to be $B(psi(3686) to p bar{p} eta^{prime}) = (1.10pm0.10pm0.08)times10^{-5}$ and $B(J/psi to p bar{p} eta^{prime})=(1.26pm0.02pm 0.07)times10^{-4}$, where the first uncertainties are statistical and the second ones systematic. Additionally, the $eta-eta^{prime}$ mixing angle is determined to be $-24^{circ} pm 11^{circ}$ based on $psi(3686) to p bar{p} eta^{prime}$, and $-24^{circ} pm 9^{circ}$ based on $J/psi to p bar{p} eta^{prime}$, respectively.
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We observe the decay $psi(3686) to n bar{n}$ for the first time and measure $psi(3686) to p bar{p}$ with improved accuracy by using $1.07times 10^8$ $psi(3686)$ events collected with the BESIII detector. The measured branching fractions are $mathcal{B}(psi(3686) to n bar{n}) = (3.06 pm 0.06 pm 0.14)times 10^{-4}$ and $mathcal{B}(psi(3686) to p bar{p}) = (3.05 pm 0.02 pm 0.12) times 10^{-4}$. Here, the first uncertainties are statistical and the second ones systematic. With the hypothesis that the polar angular distributions of the neutron and proton in the center-of-mass system obey $1+alpha cos^2theta$, we determine the $alpha$ parameters to be $alpha_{nbar{n}} = 0.68 pm 0.12 pm 0.11$ and $alpha_{pbar{p}} = 1.03 pm 0.06 pm 0.03$ for $psi(3686)to nbar{n}$ and $psi(3686)to pbar{p}$, respectively.
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 $(6.4pm0.2pm0.6)times 10^{-5}$.
Nucleon pole contributions in $J/psi to N bar N pi$, $p bar p eta$, $p bar p eta^{prime}$ and $p bar{p} omega$ decays are re-studied. Different contributions due to PS-PS and PS-PV couplings in the $pi$-N interaction and the effects of $NNpi$ form factors are investigated in the $J/psi to N bar N pi$ decay channel. It is found that when the ratio of $|F_0| /|F_M|$ takes small value, without considering the $NNpi$ form factor, the difference between PS-PS and PS-PV couplings are negligible. However, when the $NNpi$ form factor is included, this difference is greatly enlarged. The resultant decay widths are sensitive to the form factors. As a conclusion, the nucleon-pole contribution as a background is important in the $J/psito Nbar{N}pi$ decay and must be accounted. In the $J/psito Nbar{N}eta$ and $Nbar{N}eta$ decays, its contribution is less than 0.1% of the data. In the $J/psito Nbar{N}omega$ decay, it provides rather important contribution without considering form factors. But the contribution is suppressed greatly when adding the off-shell form factors. Comparing these results with data would help us to select a proper form factor for such kind of decay.
An amplitude analysis of flavour-untagged $B_s^0 to J/psi p bar{p}$ decays is performed using a sample of $797pm31$ decays reconstructed with the LHCb detector. The data, collected in proton-proton collisions between 2011 and 2018, correspond to an integrated luminosity of 9 $text{fb}^{-1}$. Evidence for a new structure in the $J/psi p$ and $J/psi bar{p}$ systems with a mass of $4337 ^{+7}_{-4} ^{+2}_{-2}~text{MeV}$ and a width of $29 ^{+26}_{-12} ^{+14}_{-14}~text{MeV}$ is found, where the first uncertainty is statistical and the second systematic, with a significance in the range of 3.1 to 3.7 $sigma$, depending on the assigned $J^P$ hypothesis.
Using the data samples of $1.31times 10^9$ $J/psi$ events and $4.48times 10^8$ $psi(3686)$ events collected with the BESIII detector, partial wave analyses on the decays $J/psi$ and $psi(3686) to pi^+pi^-eta^prime$ are performed with a relativistic covariant tensor amplitude approach. The dominant contribution is found to be $J/psi$ and $psi(3686)$ decays to $rhoeta^prime$. In the $J/psi$ decay, the branching fraction ${cal B}(J/psito rhoeta^prime)$ is determined to be $(7.90pm0.19(mathrm{stat})pm0.49(mathrm{sys}))times 10^{-5}$. Two solutions are found in the $psi(3686)$ decay, and the corresponding branching fraction ${cal B}(psi(3686)to rhoeta^prime)$ is $(1.02pm0.11(mathrm{stat})pm0.24(mathrm{sys}))times 10^{-5}$ for the case of constructive interference, and $(5.69pm1.28(mathrm{stat})pm2.36(mathrm{sys}))times 10^{-6}$ for destructive interference. As a consequence, the ratios of branching fractions between $psi(3686)$ and $J/psi$ decays to $rhoeta^prime$ are calculated to be $(12.9pm1.4(mathrm{stat})pm3.1(mathrm{sys}))$% and $(7.2pm1.6(mathrm{stat})pm3.0(mathrm{sys}))$%, respectively. We also determine the inclusive branching fractions of $J/psi$ and $psi(3686)$ decays to $pi^+pi^-eta^prime$ to be $(1.36pm0.02(mathrm{stat})pm0.08(mathrm{sys}))times 10^{-4}$ and $(1.51pm0.14(mathrm{stat})pm 0.23(mathrm{sys}))times 10^{-5}$, respectively.
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