Glueballs and other resonances with large gluonic components are predicted as bound states by Quantum Chromodynamics (QCD). The lightest (scalar) glueball is estimated to have a mass in the range from 1 to 2 GeV/c**2; a pseudoscalar and tensor glueball are expected at higher masses. Many different experiments exploiting a large variety of production mechanisms have presented results in recent years on light mesons with J(PC) = 0(++), 0(-+), and 2(++) quantum numbers. This review looks at the experimental status of glueballs. Good evidence exists for a scalar glueball which is mixed with nearby mesons, but a full understanding is still missing. Evidence for tensor and pseudoscalar glueballs are weak at best. Theoretical expectations of phenomenological models and QCD on the lattice are briefly discussed.
We revisit the mixing mechanism for pesudscalar mesons and glueball which is introduced by the axial vector anomaly. We demonstrate that the physical mass of the pseudoscalar glueball does not favor to be lower than 1.8 GeV if all the parameters are reasonably constrained. This conclusion, on the one hand, can accommodate the pseudoscalar glueball mass calculated by Lattice QCD, and on the other hand, is consistent with the high-statistics analyses at BESIII that all the available measurements do not support the presence of two closely overlapping pseudoscalar states in any exclusive channel. …
Using 53 pb$^{-1}$ of $e^+e^-$ annihilation data taken at $\sqrt{s}=3.686$ GeV, a comprehensive study has been made of the radiative decays of samples of 5.1 million $J/ψ$ and 24.5 million $ψ(2S)$ into pairs of pseudoscalar mesons, $π^+π^-$, $π^0π^0$, $K^+K^-$, $K_S^0K_S^0$, and $ηη$. Product branching fractions for the radiative decays of $J/ψ$ and $ψ(2S)$ to scalar resonances $f_0(1370,1500,1710,2100, \text{and} 2200)$, and tensor resonances $f_2(1270,1525, \text{and} 2230)$ have been determined, and are discussed in relation to predicted glueballs. For $ψ(2S)$ radiative decays the search fo…
We present a detailed study of the interactions among scalar and pseudoscalar mesons and glueballs within the framework of the generalized linear sigma model in the SU(3) flavor limit. The basis of our approach is to develop a global understanding of light scalar and pseudoscalar mesons (up to around 2 GeV) and thereby explore the underlying mixings among composite quark matter fields and glueballs. The chiral sector of the Lagrangian is formulated in terms of two chiral nonets representing quark-antiquarks and tetraquarks (in the leading order, this sector contains terms with eight or fewer n…
We aim to explore the production rate of the pseudoscalar glueball in $J/ψ$ radiative decay by lattice QCD in quenched approximation. The calculation is performed on three anisotropic lattices with the spatial lattice spacing ranging from 0.222(2) fm to 0.110(1) fm. As a calibration of some systematical uncertainties, we first extract the $M1$ form factor $\hat{V}(0)$ of the process $J/ψ\toγη_{c}$ and get the result $\hat{V}(0)=1.933(41)$ in the continuum limit, which gives the partial width $Γ(J/ψ\toγη_{c})=2.47(11)$ keV. These results are in agreement with that of previous lattice studies. A…
We point out that the recent Belle measurements of the $B_{d/s} \to J/Ψη^{(')}$ decays imply large pseudoscalar glueball contents in the $η^{(\prime)}$ meson. These decays are studied in the perturbative QCD (PQCD) approach, considering the $η$-$η'$-$G$ mixing, where $G$ represents the pseudoscalar glueball. It is shown that the PQCD predictions for the $B_{d/s} \to J/Ψη^{(')}$ branching ratios agree well with the data for the mixing angle $ϕ_G\approx 30^\circ$ between the flavor-singlet state and the pure pseudoscalar glueball. Extending the formalism to the $η$-$η'$-$G$-$η_c$ tetramixing, th…
Calculations within QCD (lattice and sum rules) find the lightest glueball to be a scalar and with mass in the range of about 1000-1700 MeV. Several phenomenological investigations are discussed which aim at the identification of the scalar meson nonets of lowest mass and the super-numerous states if any. Results on the flavour structure of the light scalars f0(500), f0(980) and f0(1500) are presented; the evidence for f0(1370) is scrutinized. A significant surplus of leading clusters of neutral charge in gluon jets is found at LEP in comparison with MCs, possibly a direct signal for glueball …
We calculated the form factors of $B_{c}$ transitions into $η^{(')}$ meson and pseudoscalar Glueball, where the $B_{c}$ meson is a bound state of two different heavy flavors and is treated as a nonrelativistic state, while the mesons $η^{(')}$ and Glueball are treated as light-cone objects since their masses are smaller enough compared to the transition momentum scale. The mechanism of two gluon scattering into $η^{(')}$ dominated the form factors of $B_{c}$ decays into $η^{(')}$. We considered the $η-η'-$Glueball mixing effect, and then obtained their influences on the form factors. The form …
Crystal Barrel Results on Two-Body Decays of the Scalar Glueball
水晶桶合作观测到$\bar p p$湮灭中的标量介子共振。基于测量和分波分析，这些都是$^3$ P $_0$基态九重奏的候选者。多余的$f_0(1500)$共振被确定为一个标量基态胶球。它的特征的重要信息来自于衰变到赝标和标量介子的模式。在质量区的K介子衰变的数据达到1700 MeV，现在可以在水晶桶。提出了新的分析结果。
We study the mixing of the scalar glueball into the isosinglet mesons $f_0 (1370)$, $f_0(1500)$, and $f_0(1710)$ to describe the two-body decays to pseudoscalars. We use an effective Hamiltonian and employ the two-angle mixing scheme for $η$ and $η'$. In this framework, we analyse existing data and look forward to new data into $η$ and $η'$ channels. For now, the $f_0 (1710)$ has the largest glueball component and a sizable branching ratio into $ηη'$, testable at BESIII.
COMPASS is a fixed-target experiment at CERN SPS which focused on light-quark meson spectroscopy during the data-taking periods in 2008 and 2009. The central exclusive production of glueball candidates is studied with a 190GeV/c proton beam impinging on a liquid hydrogen target. We select centrally produced systems with two pseudo-scalar mesons in the final state. The decay of this system is decomposed in terms of partial waves, with particular attention paid to the inherent mathematical ambiguities of the amplitude analysis. We show that simple parametrisation are able to describe the mass de…
Probing Glueball content of X(2370) through heavy quarkonium radiative decays and electron-positron annihilation
Nanjing Normal University（南京师范大学）；Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；University of Chinese Academy of Sciences（中国科学院大学）
In the past few years there has been a great deal of theoretical and experimental activity related to the search for low-mass scalars, pseudoscalars, and vectors in various scenarios of physics beyond the standard model. I review the current status of this topic, focusing on results obtained since FPCP 2014.
Production of $f_0(1710)$, $f_0(1500)$, and $f_0(1370)$ in $J/ψ$ hadronic decays
基于先前提出的胶球和$Q\bar{Q}$九元混合方案，以及$J/ψ\to V f_0^i$衰变的因子分解，对$J/ψ\to V f_0 \to V PP$中$f_0^i$（$i=1$，2，3对应于$f_0(1710)$，$f_0(1500)$，和$f_0(1370)$）的产生进行了相干研究.其中$V$表示等差矢量介子$ϕ$和$ω$，$P$表示赝标介子.结果表明，$J/ψ$衰变对这些标量介子的结构非常敏感，并且在$1.5-1.7$ GeV区域存在一个胶球，这与格点QCD一致。在标量波函数中存在显著的胶球混合产生了$J/ψ\to V f_0^i\to VPP$的分支比的特殊模式，这与最近发表的BES合作的实验数据吻合得很好。
COMPASS is a fixed-target experiment at the CERN SPS which focused on light-quark hadron spectroscopy during the data taking periods in 2008 and 2009. A world-leading data set was collected with a 190GeV/c hadron beam impinging on a liquid hydrogen target in order to study, inter alia, the central exclusive production of glueball candidates in the light-meson sector. Especially the double-Pomeron exchange mechanism is well suited for the production of mesons without valence quark content. We select centrally produced systems with two pseudo-scalar mesons in the final state from the COMPASS dat…
Confronted with some surprising claims about experimentally measured or theoretically expected dependencies on the involved momentum transfer of various form factors of pseudoscalar mesons, we reassess the present status of these quantities by means of QCD sum rules. This approach provides well-developed and very efficient tools to relate in an analytical manner the parameters of QCD to the empirical properties of hadrons. Within this framework, we show that a few theoretical findings for the pion elastic form factor and one experimental result for the pion-to-photon transition form factor are…
