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Register a new userRadiative $h_{c/b}$ decays to $eta$ or $eta^prime$
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Motivated by recent measurements of the radiative decay rates of the emph{P}-wave spin singlet charmonium $h_c$ to the light meson $eta$ or $eta^prime$ by the BESIII Collaboration, we investigate the decay rates of these channels at order $alpha alpha_s^4$. The photon is radiated mainly from charm quark pairs in the lowest order Feynman diagrams, since the diagrams where a photon radiated from light quarks are suppressed by $alpha_s$ or the relative charm quark velocity $v$, due to Charge parity conservation. The form factors of two gluons to $eta$ or $eta^prime$ are employed, which are the major mechanism for $eta$ and $eta^prime$ productions. $eta(eta^prime)$ is treated as a light cone object when we consider that the parent charmonium mass is much heavier than that of the final light meson. We obtain the branching ratio ${cal B}(h_cto gammaeta^prime) = (1.94^{+0.70}_{-0.51})times 10^{-3}$ in the nonrelativistic QCD approach, which is in agreement with the BESIII measurement. The prediction of the branching ratio of $h_cto gammaeta$ is also within the range of experimental error after including the larger uncertainty of the total decay width $Gamma_{h_c}$. The applications of these formulae to the radiative decays to $eta(eta^prime)$ of the emph{P}-wave spin singlet bottomonium $h_b(nP)$ are presented. These studies will shed some light on the $eta - eta^prime$ mixing effects, the flavor SU(3) symmetry breaking, as well as the nonperturbative dynamics of charmonium and bottomonium.
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u007fA search for radiative decays of the $P$-wave spin singlet charmonium resonance $h_c$ is performed based on $4.48 times 10^{8}$ $psi$ events collected with the BESIII detector operating at the BEPCII storage ring. Events of the reaction channels $h_{c} rightarrow gamma eta$ and $gamma eta$ are observed with a statistical significance of $8.4 sigma$ and $4.0 sigma$, respectively, for the first time. The branching fractions of $h_{c} rightarrow gamma eta$ and $h_{c} rightarrow gamma eta$ are measured to be $mathcal{B}(h_{c} rightarrow gamma eta)=(1.52 pm 0.27 pm 0.29)times10^{-3}$ and $mathcal{B}(h_{c} rightarrow gamma eta)=(4.7 pm 1.5 pm 1.4)times10^{-4}$, respectively, where the first errors are statistical and the second are systematic uncertainties.
The hadronic decays eta, eta-prime -> 3 pi and eta-prime -> eta pi pi are investigated within the framework of U(3) chiral effective field theory in combination with a relativistic coupled-channels approach. Final state interactions are included by deriving s- and p-wave interaction kernels for meson-meson scattering from the chiral effective Lagrangian and iterating them in a Bethe-Salpeter equation. Very good overall agreement with currently available data on decay widths and spectral shapes is achieved.
Recently CLEO has studied the radiative decay of $Upsilon$ into $eta$ and an upper limit for the decay has been determined. Confronting with this upper limit,most of theoretical predictions for the decay fails. After briefly reviewing these predictions we re-examine the decay by separating nonperturbative effect related to the quarkonium and that related to $eta$ or $eta$, in which the later is parameterized by distribution amplitudes of gluons in $eta$. With this factorization approach we obtain theoretical predictions which are in agreement with experiment. Uncertainties in our predictions are discussed. The possibly largest uncertainties are from relativistic corrections for $J/Psi$ and the value of the charm quark mass. We argue that the effect of these uncertainties can be reduced by using quarkonium masses instead of using quark masses. An example of the reduction is shown with an attempt to explain the violation of the famous 14% rule in radiative decays of charmonia.
In this work, we propose the $4S$-$3D$ mixing scheme to assign the $Upsilon(10753)$ into the conventional bottomonium family. Under this interpretation, we further study its hidden-bottom hadronic decays with a $eta^{(prime)}$ or $omega$ emission, which include $Upsilon(10753)toUpsilon(1S)eta^{(prime)}$, $Upsilon(10753)to h_{b}(1P)eta$ and $Upsilon(10753)tochi_{bJ}omega$ ($J$=0,1,2) processes. Since the $Upsilon(10753)$ is above the $Bbar{B}$ threshold, the coupled-channel effect cannot be ignored, thus, when calculating partial decay widths of these $Upsilon(10753)$ hidden-bottom decays, we apply the hadronic loop mechanism. Our result shows that these discussed decay processes own considerable branching fractions with the order of magnitude of $10^{-4}sim 10^{-3}$, which can be accessible at Belle II and other future experiments.
We study the hadronic decays of $Lambda_{c}^{+}$ to the final states $Sigma^{+}eta$ and $Sigma^+eta^prime$, using an $e^{+}e^{-}$ annihilation data sample of 567 pb$^{-1}$ taken at a center-of-mass energy of 4.6 GeV with the BESIII detector at the BEPCII collider. We find evidence for the decays $Lambda_{c}^{+}rightarrowSigma^{+}eta$ and $Sigma^+eta^prime$ with statistical significance of $2.5sigma$ and $3.2sigma$, respectively. Normalizing to the reference decays $Lambda_c^+toSigma^+pi^0$ and $Sigma^+omega$, we obtain the ratios of the branching fractions $frac{{mathcal B}(Lambda_c^+toSigma^+eta)}{{mathcal B}(Lambda_c^+toSigma^+pi^0)}$ and $frac{{mathcal B}(Lambda_c^+toSigma^+eta^prime)}{{mathcal B}(Lambda_c^+toSigma^+omega)}$ to be $0.35 pm 0.16 pm 0.03$ and $0.86 pm 0.34 pm 0.07$, respectively. The upper limits at the 90% confidence level are set to be $frac{{mathcal B}(Lambda_c^+toSigma^+eta)}{{mathcal B}(Lambda_c^+toSigma^+pi^0)}<0.58$ and $frac{{mathcal B}(Lambda_c^+toSigma^+eta^prime)}{{mathcal B}(Lambda_c^+toSigma^+omega)}<1.2$. Using BESIII measurements of the branching fractions of the reference decays, we determine $mathcal B({Lambda_{c}^{+}rightarrowSigma^{+}eta})=(0.41pm0.19pm0.05)%$ ($<0.68%$) and $mathcal B({Lambda_{c}^{+}rightarrowSigma^{+}eta})=(1.34pm0.53pm0.21)%$ ($<1.9%$). Here, the first uncertainties are statistical and the second systematic. The obtained branching fraction of $Lambda_c^+toSigma^+eta$ is consistent with the previous measurement, and the branching fraction of $Lambda_{c}^{+}rightarrowSigma^{+}eta^{prime}$ is measured for the first time.
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