We study meson-meson interactions using an extended $q^2\bar{q}^2(g)$ basis that allows calculating coupling of an ordinary meson-meson system to a hybrid-hybrid one. We use a potential model matrix in this extended basis which at quark level is known to provide a good fit to numerical simulations of a $q^2\bar{q}^2$ system in pure gluonic theory for static quarks in a selection of geometries. We use a combination of resonating group method formalism and Born approximation to include the quark motion using wave functions of a $q\bar{q}$ potential within a cluster. This potential is taken to be quadratic for ground states and has an additional smeared $\frac{1}{r}$ (Gaussian) for the matrix elements between hybrid mesons. For the parameters of this potential, we use values chosen to 1) minimize the error resulting from our use of a quadratic potential and 2) best fit the lattice data for differences of $Σ_{g}$ and $Π_{u}$ configurations of the gluonic field between a quark and an antiquark. At the quark (static) level, including the gluonic excitations was noted to partially replace the need for introducing many-body terms in a multi-quark potential. We study how successful such a replacement is at the (dynamical) hadronic level of relevance to actual hard experiments. Thus we study effects of both gluonic excitations and many-body terms on mesonic transition amplitudes and the energy shifts resulting from the second order perturbation theory (i.e. from the respective hadron loops). The study suggests introducing both energy and orbital excitations in wave functions of scalar mesons that are modelled as meson-meson molecules or are supposed to have a meson-meson component in their wave functions.
We present a short survey of the theoretical expectations on glueballs and hybrids as well as of the present phenomenological status. The possibility to obtain new information on gluonic mesons from the study of gluon jets in comparison to quark jets is discussed.
Non-perturbative QCD mechanisms are of fundamental importance in strong interaction physics. In particular, the flavor singlet axial anomaly leads to a gluonic pole mechanism which has been shown to explain the $η^{\prime}$ mass, violations of the OZI rule and more recently the proton spin. We show here that the interaction derived from the gluonic pole exchange explains the high momentum transfer behavior of the photoproduction cross sections of vector mesons at JLab energies.
On the basis of the confinement mechanism earlier proposed by author, the electric form factor of $η$-meson is nonperturbatively calculated. The latter is then applied to describe electromagnetic decay $η\to2γ$ which entails estimates for parameters of the confining SU(3)-gluonic field in $η$-meson. The corresponding estimates of the gluon concentrations, electric and magnetic colour field strengths are also adduced for the mentioned field.
A quarkonium-gluonium mixing scheme previously developed to describe the characteristic of the pseudoscalar mesons is applied to axial and tensor mesons. The parameters of the model are determined by fitting the eigenvalues of a mass matrix. The corresponding eigenvectors give the proportion of light quarks, strange quarks and glueball in each meson. However the predictions of the model for branching ratios and electromagnetic decays are incompatible with the experimental results. These results suggest the absence of gluonic components in the states of axial and tensor isosinglet mesons analyz…
On the basis of the confinement mechanism earlier proposed by author the electric formfactor of $π^0$-meson is nonperturbatively calculated. The latter is then applied to describing electromagnetic decays $π^0\to2γ$ and $π^0\to e^+e^-γ$ which entails estimates for parameters of the confining SU(3)-gluonic field in $π^0$-meson. The corresponding estimates of the gluon concentrations, electric and magnetic colour field strengths are also adduced for the mentioned field.
The confinement mechanism proposed earlier by the author is applied to estimate the possible parameters of the confining SU(3)-gluonic field in an $η^\prime$-meson. For this aim the electric form factor of an $η^\prime$-meson is nonperturbatively computed in an explicit analytic form. The estimates obtained are also consistent with the width of the electromagnetic decay $η^\prime\to2γ$. The corresponding estimates of the gluon concentrations, electric and magnetic colour field strengths are also adduced for the mentioned field at the scales of the meson under consideration.
The chromoelectric polarizability of mesons governs the strength of the gluonic van der Waals force and therefore of non-quark-exchange processes in hadronic physics. We compute the polarizability of heavy mesons with the aid of lattice gauge theory and the Born--Oppenheimer adiabatic expansion. We find that the operator product expansion breaks down at surprisingly large quarks masses due to nonperturbative gluodynamics and that previous conclusions concerning $J/ψ$--nuclear matter interactions and $J/ψ$ dissociation in the quark-gluon plasma must be substantially modified.
We have examined decays of low-lying gluonic excitations of mesons (hybrids) by chromoelectric flux-tube breaking. An analytical calculation of non-relativistic flux-tube model decay amplitudes is performed in an harmonic oscillator approximation. Specific decay signatures of all $J^{PC}$ charmonium hybrids are identified and the widths predicted. We introduce a new selection rule which can be used to understand the systematics of numerical decay calculations.
The eta(1760) may be significantly produced in J/Psi radiative decay. We deduce from experimental data that its branching ratio to two gluons is bounded, 0.4 +- 0.3 < BR(eta(1760) -> gg) < 0.9 +- 0.3, consistent with gluonic admixture. Moreover, the expectation that there should be an isoscalar analogue of the gluonic (hybrid) meson candidate pi(1800) is argued to reinforce hybrid admixture in eta(1760). Two-gluon coupling of hybrids is estimated in a spectator model to be considerably larger than that of quarkonium. In addition, the two-photon coupling of eta(1760) is estimated to be 1.4 +- 0…
The gluonic widths of four leading glueball candidates are determined from their production in radiative quarkonium decays, allowing quantitative estimation of their glue content. Lattice predictions for the scalar and tensor channels seem to be in reasonable agareement with present data (allowing for mixing with $q \bar{q}$ states). However there is a glueball-like-state in the pseudoscalar spectrum whose mass is considerably lower than expected from lattice estimates.
We report on some interesting recent theoretical and experimental advances on J^PC exotics and hybrid mesons. These are the decay selection rules governing J^PC exotic decay, the experimental evidence for a J^PC = 1^-+ exotic in eta pi and rho pi, and the production of charmonium hybrids at forthcoming B-factories.
The observed inclusive decay of B-mesons into eta' + X is interpreted as the consequence of the gluonic decay of the b-quark into an s-quark. As a result of the QCD anomaly this decay proceeds partly as the decay b ---> s + eta', similar to b ---> s + J/psi. The hadronic recoiling system is found to have a relatively large mass. Analogously one expects a decay of the type b ---> s + sigma. The branching ratios for these decays are large (of the order of 10%). The results indicate that there is no room for an anomalously large chromomagnetic decay mode of the b-quark. Gluon jets are expected to…
The inclusive and exclusive B decays into the eta' meson plus others are investigated in a model based on the QCD anomaly. The invariant mass distribution is discussed. The constraint of the effective coupling is obtained from the data of the exclusive decay modes. The branching ratio of J/psi -> eta'eta gamma is predicted to be as large as 5.4*10^{-5}, which can be tested in the forthcoming CLEO-c experiments.
We review the phenomenological and theoretical evidences for dynamical gluon mass generation and the main features of the glueball spectrum in (pure gauge) Yang-Mills theories. The mixing between glueball and conventional $\bar q q$ states in $f_0$ scalar mesons is discussed. For pseudoscalar mesons, the inclusion of the glue field in an effective low energy theory is presented leading to a third isoscalar $η''$ partner of the $η$ and $η'$. Branching ratios for processes involving $η''$ are given and, when available, compatible with data for $η(1405)$.
The existence of glueballs is predicted in QCD, the lightest one with quantum numbers J^{PC}=0^{++}, but different calculations do not well agree on its mass in the range below 1800 MeV. Several theoretical schemes have been proposed to cope with the experimental data which often have considerable uncertainties. Further experimental studies of the scalar meson sector are therefore important and we discuss recent proposals to study leading clusters in gluon jets and charmless B-decays to serve this purpose.
We develop tools to determine the gluonic content of a resonance of known mass, width and $J^{PC}$ from its branching fraction in radiative quarkonium decays and production cross section in $γγ$ collisions. We test the procedures by applying them to known $q\bar{q}$ mesons, then analyze four leading glueball candidates. We identify inconsistencies in data for $J/ψ\to γf_0(1500)$ and $J/ψ\to γf_J(1710)$ whose resolution can quantify their glueball status.When $Γ(f_0(1500) \to γγ)$ and $Γ(f_J(1710) \to γγ)$ are known, the $n\bar{n}, s\bar{s},gg$ mixing angles can be determined. The enigmatic sit…
Lattice QCD gives reliable predictions for hybrid charmonium and multi-GeV glueball masses. Proton-antiproton annihilation may offer an excellent opportunity for the first observation of these states. There are two distinct possible programs: The search for J^PC-exotic and non-J^PC-exotic states. The latter program represents substantially higher cross sections and does not absolutely require partial wave analysis, two very attractive features. The program can be performed with a varying pbar energy <10 GeV and a fixed target.
Currently, the long-standing issue concerning the size of the gluonic content of the eta' and eta mesons remains unsettled. With this in mind we consider the central exclusive production (CEP) of eta', eta meson pairs in the perturbative regime, applying the Durham pQCD-based model of CEP and the `hard exclusive' formalism to evaluate the meson production subprocess. We calculate for the first time the relevant parton-level processes gg --> qqbar gg and gg --> gggg, where the final-state gg and qqbar pairs form a pseudoscalar flavour-singlet state. We observe that these amplitudes display some…
We present the results of recent work on the central exclusive production of meson pairs. We concentrate on the case of flavour-singlet pseudoscalar mesons eta, eta' and show that the central exclusive process, as modelled using a recent novel application of the 'hard exclusive' perturbative formalism, is potentially highly sensitive to the size of the gluon content of these states. We also discuss the exclusive production of meson pairs in the lower mass region, and present the first results of the new Dime Monte Carlo.
The paper is devoted to applying the confinement mechanism proposed earlier by one of the authors to estimate the possible parameters of the confining SU(3)-gluonic field in vector $ϕ$-meson. The estimates obtained are consistent with the leptonic widths of the given meson. The corresponding estimates of the gluon concentrations, electric and magnetic colour field strengths are also adduced for the mentioned field at the scales of the meson under consideration.
We interpret the spectrum of meson states recently obtained in non-perturbative lattice QCD calculations in terms of constituent quark-antiquark bound states and states, called `hybrids', in which the qqbar pair is supplemented by an excitation of the gluonic field. We identify a lightest supermultiplet of hybrid mesons with JPC = (0,1,2)-+, 1-- built from a gluonic excitation of chromomagnetic character coupled to qqbar in an S-wave. The next lightest hybrids are suggested to be quark orbital excitations with the same gluonic excitation, while the next distinct gluonic excitation is significa…
We discuss the recent observation of f_0(980) in charmless B-decays and in gluon jets which hints toward a gluonic coupling of this meson similar to eta'. Further predictions on B-decays into scalar particles are presented. Charmless B decays also show a broad K Kbar (and possibly pi pi) S-wave enhancement which we relate to the 0^{++} glueball. These gluonic mesons represent a sizable fraction of the theoretically derived decay rate for b -> sg.
In this paper, lattice simulations are used to propose a potential model for gluonic excited $Σ^-_u$ states of bottomonium meson . This proposed model is used to calculate radial wave functions, masses and radii of $Σ_u^-$ bottomonium hybrid mesons. Here, gluonic field between a quark and an antiquark is treated as in the Born-Oppenheimer expansion, and Schr$\ddot{o}$dinger equation is numerically solved employing shooting method. Results of calculated masses for $Σ^-_{u}$ state are in quite good agreement with the lattice simulations.
Gaussian QCD sum-rules are ideally suited to the study of mixed states of gluonium (glueballs) and quark ($q\bar q$) mesons because of their capability to resolve widely-separated states of comparable strength. The analysis of the Gaussian QCD sum-rules (GSRs) for all possible two-point correlation functions of gluonic and non-strange ($I=0$) quark scalar ($J^{PC}=0^{++}$) currents is discussed. For the non-diagonal sum-rule of gluonic and $q\bar q$ currents we show that perturbative and gluon condensate contributions are chirally suppressed compared to non-perturbative effects of the quark co…
New experimental information on the non-exotic J^PC = 0^-+ isovector seen at 1.8 GeV by VES yields convincing evidence of its excited gluonic (hybrid) nature when a critical study of alternative quarkonium assignments is made in the context of ^3 P_0 decay by flux-tube breaking. Production of this gluonic excitation via meson exchange is promising, although its two photon production vanishes.
The confinement mechanism proposed earlier by the author is employed for to compute the decay constants $f_P$ corresponding to leptonic decays $P\to l^\pm+ν_l$, $l=μ, e$, where $P$ stands for any meson from $π^\pm$, $K^\pm$. For this aim the weak axial form factor of $P$-meson is nonperturbatively calculated. The study entails estimates for parameters of the confining SU(3)-gluonic field in charged pions and kaons. The corresponding estimates of the gluon concentrations, electric and magnetic colour field strengths are also adduced for the mentioned field at the scales of the mesons under cons…
Gaussian QCD sum-rules are used to analyze all possible two-point correlation functions of scalar gluonic and quark currents. The independent predictions of the masses and relative coupling strengths from the different correlators are remarkably consistent with a scenario of two scalar states that couple to nearly-maximal mixtures of quark and gluonic currents.
We provide an overview of theoretical developments on hybrid mesons and glueballs in the last year at this turn of the millenium conference. Cracks in potential models of conventional mesons are developing. Hybrid meson adiabatic surfaces have been calculated and interpreted, experimental J^PC exotics have hybrid meson, four-quark state or non-resonant interpretations, and the strong decay mechanism of hybrids has been studied. All theoretical progress on hybrid mesons in the last year is mentioned. Overall features of glueballs are visited: decays and the successes of the large N_c limit. Two…
The $η$-$η^\prime$ pseudoscalar mixing angle and the gluonium content of the $η^\prime$ meson are deduced from an updated phenomenological analysis of $J/ψ$ decays into a vector and a pseudoscalar meson. The values for the mixing angle and the gluonic content of the $η^\prime$ wave function are $ϕ_P=(44.5\pm 4.3)^\circ$ and $Z^2_{η^\prime}=0.28\pm 0.21$, respectively.
We study the narrow decay width of low-lying penta-quark baryons in the QCD string theoryin terms of gluonic excitations. In the QCD string theory, the penta-quark baryon decays via a gluonic-excited state of a baryon and meson system, where a pair of Y-shaped junction and anti-junction is created. Since lattice QCD shows that the lowest gluonic-excitation energy takes a large value of about 1 GeV, the decay of the penta-quark baryon near the threshold is considered as a quantum tunneling process via a highly-excited state (a gluonic-excited state) in the QCD string theory. This mechanism stro…
The spin-independent and transversity generalised form factors (GFFs) of the $ϕ$ meson are studied using lattice QCD calculations with light quark masses corresponding to a pion mass $m_π\sim450(5)$ MeV. One transversity and three spin-independent GFFs related to the lowest moments of leading-twist spin-independent and transversity gluon distributions are obtained at six non-zero values of the momentum transfer up to 1.2 GeV$^2$. These quantities are compared with the analogous spin-independent quark GFFs and the electromagnetic form factors determined on the same lattice ensemble. The results…
The models for hybrid mesons are discussed, in which the gluonic excitations manifest themselves as the vibrations of the quark- antiquark QCD string. The predictions for the spectra, decays and mixing with hadronic channels are presented.
The heavy quark expansion of Quantum Chromodynamics and the strong coupling flux tube picture of nonperturbative glue are employed to develop the phenomenology of hybrid meson decays. The decay mechanism explicitly couples gluonic degrees of freedom to the pair produced quarks and hence does not obey the well known, but model-dependent, selection rule which states that hybrids do not decay to pairs of L=0 mesons. However, the nonperturbative nature of gluonic excitations in the flux tube picture leads to a new selection rule: light hybrids do not decay to pairs of identical mesons. New feature…
We review recent experimental results on hadronic decays and lifetimes of hadrons containing b and c quarks. We discuss charm counting and the semileptonic branching fraction in B decays, the color suppressed amplitude in B and D decay, and the search for gluonic penguins in B decay.
Gaussian sum-rules, which are related to a two-parameter Gaussian-weighted integral of a hadronic spectral function, are able to examine the possibility that more than one resonance makes a significant contribution to the spectral function. The Gaussian sum-rules, including instanton effects, for scalar gluonic and non-strange scalar quark currents clearly indicate a distribution of the resonance strength in their respective spectral functions. Furthermore, analysis of a two narrow resonance model leads to excellent agreement between theory and phenomenology in both channels. The scalar quark …
I review some outstanding issues in meson spectroscopy. The most important qualitative issue is whether hadrons with explicit gluonic degrees of freedom exist. To answer this question requires a much better understanding of conventional $q\bar{q}$ mesons. I therefore begin by examining the status of conventional meson spectroscopy and how the situation can be improved. The expected properties of gluonic excitations are discussed with particular emphasis on hybrids to give guidance to experimental searches. Multiquark systems are commented upon as they are likely to be important in the mass reg…
I describe the results from lattice studies of probing the vacuum with static colour sources. Topics include (i) Twang the flux tube: string models and hybrid mesons. (ii) Charge up the flux tube: adjoint and sextet sources. (iii) Several sources: how does the colour flux get arranged?
Using the QCD string theory, we investigate the physical reason of the narrow width of penta-quark baryons in terms of the large gluonic-excitation energy. In the QCD string theory, the penta-quark baryon decays via a gluonic-excited state of a baryon and meson system, where a pair of Y-shaped junction and anti-junction is created. On the other hand, we find in lattice QCD that the lowest gluonic-excitation energy takes a large value of about 1 GeV. Therefore, in the QCD string theory, the decay of the penta-quark baryon near the threshold is considered as a quantum tunneling process via a hig…
We discuss states in the meson spectrum which have explicit gluonic components. Glueballs (with no valence quarks) and hybrid mesons (with valence quarks) are both reviewed. We present in some detail lattice simulation results. ( to appear in proceedings of QCD-20 years, Aachen Workshop)
The mass difference of $c$ and $u$ quarks is similar to the energy needed to excite gluonic degrees of freedom in strong QCD. This underpins the degeneracy of $D$ and a recently observed candidate hybrid excitation of the $π$ at$\sim 1.8$GeV and may generate a strong analogue of Penguin mixing together with a measurable CP-violation in $D$ and $D_s$ decays.
It is shown that the QCD anomaly may lead to an abnormal mixing behavior of the axial vector mesons similar to the pseudoscalar mesons. These mixing effects, involving a gluonic axial vector state, generate a non-vanishing strange quark component in the nucleon. They reduce the matrix element of the singlet axial vector in comparison to the value obtained in a naive quark model. The results are in agreement with the data obtained in the polarized lepton-nucleon scattering experiments.
We study $\bar qq$-hybrid mixing for the light vector mesons and $\bar qq$-glueball mixing for the light scalar mesons in Monte-Carlo based QCD Laplace sum rules. By calculating the two-point correlation function of a vector $\bar qγ_μq$ (scalar $\bar q q$) current and a hybrid (glueball) current we are able to estimate the mass and the decay constants of the corresponding mixed "physical state" that couples to both currents. Our results do not support strong quark/gluonic mixing for either the $1^{--}$ or the $0^{++}$ states.
An effective hamiltonian for heavy quarkonia is derived from QCD by separating gluonic fields in background and quantum fields and neglecting anharmonic contributions. Mesonic states with nonperturbative gluonic components are constructed. These states are invariant under gauge changes of the background fields and form an orthogonal basis. The effective hamiltonian is diagonalized in this basis in a systematic $1/m$- and short distance expansion. For very heavy quarkonia, we obtain an effective potential similar to the phenomenological funnel potential. We compare our method to $2^{\rm nd}$ or…
At high energy, the photoproduction or electroproduction of Vector Mesons allow to prepare a beam of quark-antiquark pairs of a given flavor. At high momentum transfer, the study of the scattering of these pairs on a nucleon opens up an original window on the quark-gluon structure of hadronic matter, which may eventually shed light on its gluonic content, on correlations between quarks and on the van der Walls part of the interaction between hadrons.
The constituent nature of candidate gluonic mesons can be studied by comparing their production in quark and gluon jets. The production rate for such mesons depends on the colour confinement processes at the end of the perturbative evolution. Whereas we expect enhanced production of hybrids in the fragmentation region of a gluon jet, the rate for glueballs depends on the relative importance of colour triplet and colour octet neutralization. These neutralization processes can be studied independently in events with large rapidity gaps. If octet processes turn out important the recently suggeste…
An analytic calculation of the breaking of excited chromoelectric flux-tubes is performed in an harmonic oscillator approximation and applied to predict the dynamics of all $J^{PC}$ low-lying gluonic excitations of mesons (hybrids). Widths, branching ratios and production dynamics of some recently discovered $J^{PC} = 1^{-+}, 0^{-+}$ and $1^{--}$ mesons are found to be in remarkable agreement with these results. We introduce the selection rules that can be used to understand the systematics of numerical decay calculations and we find possible significant breaking of these rules for specific ch…
Using our analytical expressions that well model the lattice simulations of the gluonic excitations, we use the extended quark potential model to study the effects of orbital and radial excitations on the masses and sizes of conventional and hybrid $B_c$ mesons. A non relativistic formalism is used to numerically calculate the wave functions using the shooting method; this allows us also calculating the $E1$, $M1$ radiative partial widths for conventional meson to meson and hybrid to hybrid transitions. We incorporate spin mixing and compare our calculated spectrum and decay widths with the av…
The inclusive nonleptonic transition rate of B meson in gluonic penguin channel is calculated in QCD using the heavy quark mass expansion. We found the branching ratio to be approximately 0.25%.
In the framework of quark models, hybrid mesons are either seen as two-body $q\bar q$ systems with an excited flux tube connecting the quark to the antiquark or as three-body $q\bar q g$ systems including a constituent gluon. In this work we show that, starting from the three-body wave function of the $q\bar q g$ hybrid meson in which the gluonic degrees of freedom are averaged, the excited flux tube picture emerges as an equivalent $q\bar q$ potential. This equivalence between the excited flux tube and the constituent gluon approach is confirmed for heavy hybrid mesons but, for the first time…
Thermodynamics and the phase structure of the Polyakov loop-extended two flavor chiral quark-meson model (PQM) are explored. The analysis of the PQM model is based on the functional renormalization group (FRG) method. An appropriate truncation of the effective action with quarks coupled to background gluonic fields is introduced. Within this scheme, we derive the renormalization group flow equation for the scale-dependent thermodynamic potential at finite temperature and density in the presence of a symmetry breaking external field. The influence of fluctuations and of the background gluon fie…
The ground and first excited states of the hybrid charmonium ${\bar c} c g$, with non-exotic quantum numbers $J^{PC}=0^{-+}$, $1^{--}$ and $1^{++}$ are investigated using quenched lattice QCD. They are completely ignored in the literature, only because their ground states are degenerate with $η_c$, $J/ψ$, and $χ_{c1}$, and are difficult to be distinguished from these conventional charmonium mesons in experiment. However, we observe strong gluonic radial excitations in the first excited states; We predict that their masses are 4.352(225)GeV, 4.379(149)GeV and 7.315(257)GeV, completely different…
We study gluonic excitations inside a $B_{c} $ meson in the constituent gluon model, treating a bottom-charm hybrid meson $ c \bar{b} g $ as a three-body system. We obtain the mass spectra for the hybrid mesons with magnetic gluon and electric gluon and see that their lowest states appear above the $ D B $ threshold. Also, we consider the decays of the low-lying states of the hybrid meson into $ DB , \; D^{*} B, DB^{*} $, $ D^{*}B^{*} $, $ D_{s} B_{s} $, and $D_{s} B_{s}^{*} $ mesons, developing an existing model for the strong decays. We estimate their partial decay widths and find that the w…
As a topic of "quantum color dynamics", we study various mass generation of colored particles and gluonic dressing effect in a non-perturbative manner, using the Schwinger-Dyson (SD) formalism in (scalar) QCD. First, we review dynamical quark-mass generation in QCD in the SD approach as a typical fermion-mass generation via spontaneous chiral-symmetry breaking. Second, using the SD formalism for scalar QCD, we investigate the scalar diquark, a bound-state-like object of two quarks, and its mass generation, which is clearly non-chiral-origin. Here, the scalar diquark is treated as an extended c…
The status of non-perturbative QCD calculations for mesons with gluonic excitation is presented. Lattice results for the glueball spectrum are reviewed. For hybrid mesons, the heavy quark results are summarised and new results are presented for light quarks. Preliminary results for the spectrum of light-quark hybrid mesons indicate substantial mixing with quark model states for non-exotic $J^{PC}$. For the exotic $J^{PC}$ hybrid mesons, the $J^{PC}=1^{-+}$, $0^{+-}$ and $2^{+-}$ states are explored.
The amplitudes of $π$-meson decays are calculated in a relativistic nonperturbative quark model which assumes that mesons are made of a quark antiquark pair and of a scalar neutral component representing the contribution of the nonelementary fluctuations of the quark gluonic field. The experimental data can be fitted in a satisfactory manner using current quark masses $m_u\approx1.5\ MeV, m_d\approx9\ MeV$.
We study hybrid mesons from the clover and improved gauge actions at $β=2.6$ on the anisotropic $12^3\times36$ lattice using our PC cluster. We estimate the mass of $1^{-+}$ light quark hybrid as well as the mass of the charmonium hybrid. The improvement of both quark and gluonic actions, first applied to the hybrid mesons, is shown to be more efficient in reducing the lattice spacing and finite volume errors.
Signatures of dominant and central production of glueballs (binary gluonic mesons) in heavy ion and hadromic collisions are discussed. Search strategies are proposed.
