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Register a new userScalar charmonium and glueball mixing in $e^+ e^-to J/psi X$
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We study the possibility of the scalar charmonium and glueball mixing in $e^+ e^-$ annihilation at $sqrt{s}=10.6$ GeV. The effects can be used to explain the unexpected large cross section ($12pm 4$ fb) and the anomalous angular distribution ($alpha= -1.1^{+0.8}_{-0.6}$) of the exclusive $e^+e^-to J/psichi_{c0}$ process observed by Belle experiments at KEKB. We calculate the helicity amplitudes for the process $e^+ e^- to J/psi H(0^{++})$ in NRQCD, where $H(0^{++})$ is the mixed state. We present a detailed analysis on the total cross section and various angular asymmetries which could be useful to reveal the existence of the scalar glueball state.
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We study the $e^+e^-togammaomega J/psi$ process using $11.6 ~rm fb^{-1}$ $e^+ e^-$ annihilation data taken at center-of-mass energies from $sqrt{s}=4.008~rm GeV$ to $4.600~rm GeV$ with the BESIII detector at the BEPCII storage ring. The $X(3872)$ resonance is observed for the first time in the $omega J/psi$ system with a significance of more than $5sigma$. The relative decay ratio of $X(3872)toomega J/psi$ and $pi^+pi^- J/psi$ is measured to be $mathcal{R}=1.6^{+0.4}_{-0.3}pm0.2$, where the first error is statistical and the second systematic (the same hereafter). The $sqrt{s}$-dependent cross section of $e^+e^-togamma X(3872)$ is also measured and investigated, and it can be described by a single Breit-Wigner resonance, referred to as the $Y(4200)$, with a mass of $4200.6^{+7.9}_{-13.3}pm3.0~{rm MeV}/c^2$ and a width of $115^{+38}_{-26}pm12~{rm MeV}$. In addition, to describe the $omega J/psi$ mass distribution above $3.9~rm GeV/c^2$, we need at least one additional Breit-Wigner resonance, labeled as $X(3915)$, in the fit. The mass and width of the $X(3915)$ are measured to be $3926.4pm2.2pm1.2~rm MeV/c^2$ and $3.8pm7.5pm2.6~rm MeV$, or $3932.6pm8.7pm4.7~rm MeV/c^2$ and $59.7pm15.5pm3.7~rm MeV$, respectively, depending on the fit models. The resonant parameters of the $X(3915)$ agree with those of the $Y(3940)$ in $Bto Komega J/psi$ and of the $X(3915)$ in $gammagammatoomega J/psi$ by the Belle and BABAR experiments within errors.
We report on a recent investigation of the single spin asymmetry (SSA) in low virtuality electroproduction of $J/psi$ in color evaporation model. We show that this can be used as a probe for the still unknown gluon Sivers function.
The cross section of $e^+e^- rightarrow eta J/psi$ has been measured by BESIII and Belle experiments. Fit to the $e^+e^- rightarrow eta J/psi$ line shape, three resonant structures are evident. The parameters for the three resonant structures are $M_{1}=(3980pm17pm7)$ MeV/$c^{2}$, $Gamma_{1}=(104pm32pm13)$ MeV; $M_{2}=(4219pm5pm4)$ MeV/$c^{2}$, $Gamma_{2}=(63pm9pm3)$ MeV; $M_{3}=(4401pm12pm4)$ MeV/$c^{2}$, $Gamma_{3}=(49pm19pm4)$ MeV, where the first uncertainties are statistical and the second systematic. We attribute the three structures to $psi(4040)$, $Y(4220)$ and $psi(4415)$ states. The branching fractions $mathcal{B}(psi(4040) rightarrow eta J/psi)$ and $mathcal{B}(psi(4415) rightarrow eta J/psi)$ are given. If $Y(4220)$ is taken as $psi(4S)$ state, the branching fraction $mathcal{B}(psi(4S) rightarrow eta J/psi)$ is also given. Combining all $Y(4220)$ parameters obtained from different decays, we give average parameters for $Y(4220)$, which are $M_{Y(4220)}=(4220.8pm2.4)$ MeV/$c^{2}$, $Gamma_{Y(4220)}=(54.8pm3.3)$ MeV.
We have measured several branching ratios for $psi^prime$ decay using the data collected by FNAL E835 experiment during year 2000, obtaining ${cal B}(psi^prime to e^+ e^-) = 0.0068pm0.0001pm0.0004$, ${cal B}(psi^prime to J/psi pi^+ pi^-) = 0.292pm0.005pm0.018$, ${cal B}(psi^prime to J/psi pi^0 pi^0) = 0.167pm0.005pm0.014$ and ${cal B}(psi^prime to J/psi eta) = 0.028pm0.002pm0.002$. We also present a measurement of the dipion mass distribution in the decays $psi^prime to J/psi pi pi$.
The cross section for $e^+ e^- to pi^+ pi^- J/psi$ between 3.8 GeV and 5.5 GeV is measured with a 967 fb$^{-1}$ data sample collected by the Belle detector at or near the $Upsilon(nS)$ ($n = 1, 2, ..., 5$) resonances. The Y(4260) state is observed, and its resonance parameters are determined. In addition, an excess of $pi^+ pi^- J/psi$ production around 4 GeV is observed. This feature can be described by a Breit-Wigner parameterization with properties that are consistent with the Y(4008) state that was previously reported by Belle. In a study of $Y(4260) to pi^+ pi^- J/psi$ decays, a structure is observed in the $M(pi^pmjpsi)$ mass spectrum with $5.2sigma$ significance, with mass $M=(3894.5pm 6.6pm 4.5) {rm MeV}/c^2$ and width $Gamma=(63pm 24pm 26)$ MeV/$c^{2}$, where the errors are statistical and systematic, respectively. This structure can be interpreted as a new charged charmonium-like state.
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