Based on a semiclassical expansion for quantum chromodynamics in the instanton liquid background, the correlation function of the $0^{++}$ scalar glueball current is given, and the properties of the $0^{++}$ scalar glueball are studied in the framework of Gaussian sum rules. Besides the pure classical and quantum contributions, the contributions arising from the interactions between the classical instanton fields and quantum gluons are come into play. Instead of the usual zero-width approximation for the resonance, the Breit-Wigner form for the spectral function of the finite-width resonance is adopted. The family of the Gaussian sum rules for the scalar glueball in quantum chromodynamics with and without light quarks is studied. A consistency between the subtracted and unsubtracted sum rules is very well justified, and the values of the decay width and the coupling to the corresponding current for the $0^{++}$ resonance, in which the scalar glueball fraction is dominant, are obtained.
Glueballs, an old and firm prediction of various QCD approaches (lattice QCD, bag models, AdS/QCD, effective models, etc.), have not yet been experimentally confirmed. While for glueballs below $2.6$ GeV some candidates exist, the situation for heavy glueballs (above $2.6$ GeV) is cloudy. Here, after a brief review of scalar, tensor, and pseudoscalar glueballs, we present predictions for the decays of a putative pseudotensor glueball with a lattice predicted mass of $3.04$ GeV and a putative vector glueball with a lattice predicted mass of $3.81$ GeV. Moreover, we discuss in general the width …
The widths of a glueball decay to two pions or kaons are analyzed in the pQCD framework. Our results show that the glueball ground state has small branching ratio for two-meson decay mode, which is around $10^{-2}$. The predicted values are consistent with the data of $ξ\toππ, KK$ if $ξ$ particle is a $2^{++}$ glueball. Applicability of pQCD to the glueball decay and comparison with $χ_{cJ}$ decay are also discussed.
In the framework of a semi-classical expansion for quantum chromodynamics in the instanton liquid background, the correlation function of the $0^{++}$ scalar glueball current is given. Besides the pure classical and quantum contributions, the contributions arising from the interactions between the classical instanton fields and quantum gluons are taken into account as well. Instead of the usual zero-width approximation for the resonance, the Brite-Wigner form for the spectral function of the finite-width resonance is adopted. The family of the Laplace sum rules for the scalar glueball in quant…
Contributions of fermions to the mass of the scalar glueball $0^{++}$ are calculated at two-loop level in the framework of QCD sum rules. It obviously changes the coefficients in the operator product expansion (OPE) and shifts the mass of glueball.
The mass of the lowest scalar glueball is discussed by using QCD sum rules. We find that the glueball mass is sensitive to the choice of moments and slightly depends on the radiative corrections. With the help of suitable moments and stability criteria, we get the scalar glueball mass: $1710\pm110$ MeV without radiative corrections and $1580\pm150$ MeV with radiative corrections.
The $0^{++}$ glueball mass is analyzed in the QCD sum rules. We show that in order to determine the $0^{++}$ glueball mass by using the QCD sum rules method, it is necessary to clarify the following three ingredients: (1) to choose the appropriate moment with acceptable parameters which satisfy all of the criteria; (2) to take account into the radiative corrections; (3) to estimate an additional contribution to the glueball mass from the lowest lying ${\bar q}q$ resonance. We conclude that it is the key point to choose suitable moments to determine the $0^{++}$ glueball mass, the radiative cor…
Nonperturbative Wilson coefficients of the operator product expansion (OPE) for the spin-0 glueball correlators are derived and analyzed. A systematic treatment of the direct instanton contributions is given, based on realistic instanton size distributions and renormalization at the operator scale. In the pseudoscalar channel, topological charge screening is identified as an additional source of (semi-) hard nonperturbative physics. The screening contributions are shown to be vital for consistency with the anomalous axial Ward identity, and previously encountered pathologies (positivity violat…
We calculate the mass spectrum and the decay widths of glueballs in the flux tube model. The glueball is assumed to be a closed flux tube. The breathing motion and the rotational motion are investigated using the WKB approximation. The calculated spectra is consistent with those by lattice QCD. The decay widths are also computed using Schwinger mechanism and it is shown that they have rather large values.
The heaviness of the glueball mass scale is suggested as the source of the OZI rule at low energy. The $J/ψ\to ρπ$ decay "anomaly" implies the vector glueball $O$ has mass $m_O \approx m_{J/ψ}$. Such a heavy mass is supported by other glueball studies. Glueball-meson matrix elements turn out to be not suppressed at all at the 1 GeV scale, and a simple and intuitive picture emerges which is consistent with the Gell-Mann-Okubo mass formula as well as the measured sign of $ϕ$-$ω$ mixing. The suppression of glueball mediated $\bar q_iq_i \longleftrightarrow \bar q_jq_j$ transitions and the cancell…
Based on correction from instanton-gluon interference to correlation function, the properties of the $0^{-+}$ pseudoscalar glueball is investigated in a family of finite-width Gaussian sum rules. In the framework of semiclassical expansion for quantum chromodynamics $(\textrm{QCD})$ in the instanton liquid background, the contribution arising from the the interference between instantons and the quantum gluon fields is calculated, and included in the correlation function together with pure-classical contribution from instantons and the perturbative one. The interference contribution is turned t…
Computations in the quenched approximation on the lattice predict the lightest glueball to be a scalar in the 1.5-1.8 GeV region. Here we calculate the dynamical effect the coupling to two pseudoscalars has on the mass, width and decay pattern of such a scalar glueball. These hadronic interactions allow mixing with the $q \overline q$ scalar nonet, which is largely fixed by the well-established K_0^*(1430). This non-perturbative mixing means that, if the pure gluestate has a width to two pseudoscalar channels of ~100 MeV as predicted on the lattice, the resulting hadron has a width to these ch…
The lowest dimension three-gluon currents that couple to the exotic $0^{\pm-}$ glueballs have been constructed using the helicity formalism. Based on the constructed currents, we obtain new QCD SRs that have been used to extract the masses and the decay constants of the scalar exotic $0^{\pm-}$ glueballs. We estimate the masses for the scalar state and for the pseudoscalar state to be ${m_+=9.8^{+1.3}_{-1.4}}$ GeV and $m_-=6.8^{+1.1}_{-1.2}$ GeV.
We study the vacuum properties of the pseudoscalar glueball and charmed mesons by using the so-called extended Linear Sigma Model (eLSM). This model includes scalar and pseudoscalar mesons, as well as vector and axial-vector mesons. We calculate the mesonic and baryonic decays of the pseudoscalar glueball, where we fixed its mass to $2.6$ GeV, as predicted by lattice-QCD simulations, and take a closer look at the scalar-isoscalar decay channel. As a second step, we enlarge the so-called extended linear Sigma model (eLSM) by including the charm quark to a global $U(4)_r\times U(4)_l$ chiral sym…
We investigate the correlations between the scalar meson configurations and Okuba-Zweig-Iizuka (OZI) rule violations in the hadronic decays of heavy quarkonia, e.g. $J/ψ$ and $Υ$, into isoscalar vector meson ($ϕ$ and $ω$) and scalar mesons ($f_0(1710)$, $f_0(1500)$, and $f_0(1370)$). It shows that the dramatic change of the values of the branching ratio fraction of $ϕf_0/ωf_0$ from low (e.g. in $J/ψ$ decays) to high energies (e.g. in $Υ$ decays) will not only test the glueball-$Q\bar{Q}$ mixings, but also provide important information about the mysterious OZI-rule violations within the scalars…
We present a new calculation of the mass and width of the exotic $0^{--}$ glueball in the framework of the QCD sum rules. We next construct a new current which couples to a pure $0^{--}$ gluon state and derive consistent and stable sum rules. A previously used current in this approach was shown to be inconsistent. We obtain for this state a mass $M_G=6.3^{+0.8}_{-1.1}$ GeV and an upper limit for the total width $Γ_G\leq 235$ MeV. These values can be used as an important guide for the experimental search of this exotic state. We argue that the mixing of this glueball state with $0^{--}$ tetraqu…
We prove a theorem in QCD stating that in the limit of strong coupling, $g\to\infty$, the observed spectrum of glueballs in QCD is the same of a pure Yang-Mills theory, being mixing effects due to the next-to-leading order. A full effective theory for QCD is obtained and the width of the $σ$ resonance decay is straightforwardly computed. This appears as the lowest glueball state. Vacuum gluon condensate is computed that consistently support studies on the identification of this meson as a glueball.
We investigate the two-meson decay modes for $f_0(1500)$. In this calculation we consider this resonance as a glueball. The Fock-Tani formalism is introduced to calculate the decay width.
Although marginally more complicated than the traditional Laplace sum-rules, Gaussian sum-rules have the advantage of being able to probe excited and ground states with similar sensitivity. Gaussian sum-rule analysis techniques are applied to the problematic scalar glueball channel to determine masses, widths and relative resonance strengths of low-lying scalar glueball states contributing to the hadronic spectral function. A feature of our analysis is the inclusion of instanton contributions to the scalar gluonic correlation function. Compared with the next-to-leading Gaussian sum-rule, the a…
Nonlocal gluon condensates are vacuum expectations of the product of gluon field strength tensors. Short-distance expansions of two-, three-, and four-gluon condensates are presented up to dimension-8 local operators. We propose a method for calculating the Wilson coefficients based on the presented expansions and the Feynman diagram technique in the background field approach. The method is demonstrated using the glueball current correlators as examples. Methodological aspects of the background field approach are discussed in relation to glueball studies within QCD sum rules. We confirm the re…
We investigate the impact of instantons on scalar glueball properties in a largely model-independent analytical approach based on the instanton-improved operator product expansion (IOPE) of the $0^{++}$ glueball correlator. The instanton contributions turn out to be dominant, to substantially improve the consistency of the correponding QCD sum rules, and to increase the glueball residue about fivefold.
The mixing angles between scalar isoscalar resonances and a scalar glueball are determined from their decays into two pseudoscalar mesons. For $f_0(1370)$ and $f_0(1500)$, at most a small glueball component is admitted by the data. The decay modes of $f_0(1710)$, $f_0(1770)$, $f_0(2020)$, and $f_0(2100)$ require significant glueball fractions. Above this mass, the errors in the decay frequencies become too large to extract a glueball component. The summation of all observed glueball fractions up to 2100\,MeV yields (78\er18)\%. The glueball fractions as function of the mass are consistent with…
We include instanton effects in QCD sum rules for coupled scalar glueballs and mesons. We find a light glueball/sigma as in earlier studies without instantons, but in a lattice-type pure instanton model the light glueball/sigma is not found. In the 1-2 Gev region we now find that lightest I=0 meson, in the region of the f$_o$(1370), has no direct glueball mixing, with the instanton loop replacing the glueball component. The lightest scalar mainly glueball in the region of the f$_o$(1500) is sensitive to the choice of nonperturbative gluonic parameters.
One-loop quark contributions to the dimension-four gluon condensate term in the operator product expansion (OPE) of the scalar glueball correlation function are calculated in the MS-bar scheme in the chiral limit of $n_f$ quark flavours. The presence of quark effects is shown not to alter the cancellation of infrared (IR) singularities in the gluon condensate OPE coefficients. The dimension-four gluonic condensate term represents the leading power corrections to the scalar glueball correlator and, therein, the one-loop logarithmic contributions provide the most important condensate contributio…
We investigate the hadronic two-body decay modes of the scalar-isoscalar $f_0(1370)$, $f_0(1500)$ and $f_0(1710)$ states as resulting from the mixture of the lowest lying scalar glueball with the isoscalar states of the ground state $^3P_0$ $Q\bar Q$ nonet. In the decay analysis we take into account the direct coupling of the quarkonia and glueball components of the $f_0$ states to the quarkonia components of the two-meson final state with the decay dynamics inspired by the strong coupling limit of QCD. We calculate partial decay widths for the $f_0$ states in the proposed three-state mixing s…
We discuss scenarios for scalar glueballs using arguments based on sum rules, spectral decomposition, the $\frac{1}{N_c}$ approximation, the scales of the strong interaction and the topology of the flux tubes. We analyze the phenomenological support of those scenarios and their observational implications. Our investigations hint a rich low lying glueball spectrum.
We predict glueball/oddball resonances lying on the pomeron/odderon trajectories. A simple new form of the trajectories, with threshold and asymptotic behaviour required by analyticity and unitarity, is proposed. The parameters of these (pomeron and odderon) trajectories are fitted to the data on high-energy elastic proton-proton scattering. The fitted trajectories are extrapolated to the resonance region to predict masses and widths of glueballs and oddballs. The (pomeron and odderon) trajectories may be used to calculate processes of central exclusive diffraction (CED).
A coupled-channel analysis of BESIII data on radiative $J/ψ$ decays into $ππ$, $K\bar K$, $ηη$ and $ωϕ$ has been performed. The partial-wave amplitude is constrained by a large number of further data. The analysis finds ten isoscalar scalar mesons. Their masses, widths and decay modes are determined. The scalar mesons are interpreted as mainly SU(3)-singlet and mainly octet states. Octet isoscalar scalar states are observed with significant yields only in the 1500-2100\,MeV mass region. Singlet scalar mesons are produced over a wide mass range but their yield peaks in the same mass region. The…
We show that the newly discovered scalar meson $f_0(1500)$ at LEAR has properties compatible with the lightest scalar glueball predicted by lattice QCD and incompatible with a $\qqbar$ state. We suggest that decays of glueballs are into pairs of glueballs (including $η, η'$ or $(ππ)_S$) or by mixing with nearby $Q\bar{Q}$ states. The partial widths of $f_0(1500)$ are in accord with this hypothesis, tests of which include characteristic radiative decays to $γϕ,γω, γρ$ and the prediction of a further scalar state, $f_0'(1500 - 1800)$ which couples strongly to $K\bar{K}$, $ηη$ and $ηη'$.
Ground and first radially excited scalar isoscalar meson states and a scalar glueball are described in a nonlocal U(3)xU(3) quark model. The glueball is introduced into the effective meson Lagrangian by means of the dilaton model on the base of the scale invariance of the meson Lagrangian. The scale invariance breaking by current quark masses and gluon anomalies is taken into account. The glueball anomalies turn out to be important for the description of the glueball-quarkonia mixing. The masses of five scalar isoscalar meson states and their strong decay widths are calculated. The state f_0(1…
Several key problems of QCD sum rules in the spin-0 glueball channels are resolved by implementing nonperturbative short-distance physics from direct instantons and topological charge screening. A lattice-based instanton size distribution and the IR renormalization of the nonperturbative Wilson coefficients are also introduced. Results of a comprehensive quantitative sum rule analysis are reviewed and their implications discussed.
We consider a $N_f=3$ chiral Lagrangian which describes the interaction between the pseudoscalar glueball, $J^{PC}=0^{-+}$, and scalar and pseudoscalar mesons. We calculate the decay widths of the pseudoscalar glueball, where we fixed its mass to 2.6 GeV, as predicted by lattice QCD simulations, and take a closer look in the scalar-isoscalar decaying channel. We present our results as branching ratios which are relevant for the future PANDA experiment at the FAIR facility.
The impact of QCD instantons on scalar glueball properties is studied in the framework of an instanton-improved operator product expansion (IOPE) for the 0^{++} glueball correlation function. Direct instanton contributions are found to strongly dominate over those from perturbative fluctuations and soft vacuum fields. All IOPE sum rules, including the one involving a subtraction constant, show a high degree of stability and are, in contrast to previous glueball sum rules, consistent with the low-energy theorem for the zero-momentum correlator. The predicted glueball mass m_{G}=1.53 \pm 0.2 GeV…
The ratios of partial widths for the decay of a glueball into two pseudoscalar mesons are calculated under the assumption that the production of light quark pairs ($u\bar u,d\bar d,s\bar s$) in soft gluon-\-induced reactions goes on within universal symmetry breaking. Parameter of the violation of flavour symmetry is fixed by the central hadron production data in high energy hadron collisions and/or by the ratios of radiative decay amplitudes $J/Ψ\to γη/γη'$ and $J/Ψ\to γϕϕ/γωω$. The ratios of coupling constants $glueball\toππ,K\bar K, ηη,ηη'$ which are calculated with this parameter coincide …
Some recent developments in the phenomenology of the lightest scalar glueball are summarised. Tools for determining 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 are presented. Two $q\bar{q} - G$ mixing schemes for $J^{PC} = 0^{++}$, inspired by the lattice, are shown to lead to similar phenomenology that may be tested at BEPC and in $γγ$ production at LEP2.
The center-of-gravity rule is tested for heavy and light-quark mesons. In the heavy-meson sector, the rule is excellently satisfied. In the light-quark sector, the rule suggests that the $a_0(980)$ could be the spin-partner of $a_2(1320)$, $a_1(1260)$, and $b_1(1235)$; $f_0(500)$ the spin-partner of $f_2(1270)$, $f_1(1285)$, and $h_1(1170)$; and $f_0(980)$ the spin-partner of $f_2'(1525)$, $f_1(1420)$, and $h_1(1415)$. From the decay and the production of light scalar mesons we find a consistent mixing angle $θ^{\rm s}=(14\pm4)^\circ$. We conclude that $f_0(980)$ is likely "octet-like" in SU(3…
We point out a unique mechanism to produce the relic abundance for glueball dark matter from a gauged $SU(N)_d$ hidden sector which is bridged to the standard model sector through heavy vectorlike quarks colored under gauge interactions from both sides. A necessary ingredient of our assumption is that the vectorlike quarks, produced either thermally or non-thermally, are abundant enough to dominate the universe for some time in the early universe. They later undergo dark color confinement and form unstable vectorlike-quarkonium states which annihilate decay and reheat the visible and dark sect…
An effective meson Lagrangian including a scalar glueball is constructed on the base of $U(3)\times U(3)$ chiral symmetry. The glueball is introduced into the meson Lagrangian by using the principle of scale invariance of an effective Lagrangian and the dilaton model. The singlet-octet mixing of scalar meson states is described by means of 't Hooft interaction. The contribution of the scalar and pseudoscalar anomalies into the breaking of scale invariance is taken into account. The mixing of quarkonia with the glueball is described. The mass spectrum of scalar mesons together with the glueball…
We study the three-flavor chirally and dilatation invariant extended Linear Sigma Model with (pseudo)scalar and (axial-)vector mesons as well as a scalar dilaton field whose excitations are interpreted as a glueball. The model successfully describes masses and decay widths of quark-antiquark mesons in the low-energy region up to 1.6 GeV. Here we study in detail the vacuum properties of the scalar-isoscalar channel and find that (i) a narrow glueball is only possible if the vacuum expectation value of the dilaton field is (at tree-level) quite large (i.e., larger than what lattice QCD and QCD s…
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.
We study scalar glueballs and scalar mesons at $T \neq 0$ in the soft wall holographic QCD model. We find that, using the Anti-de Sitter-Black Hole metric for all values of the temperature, the masses of the hadronic states decrease and the widths become broader when T increases, and there are temperatures for which the states disappear from the scalar glueball and scalar meson spectral functions. However, the values of the temperatures in correspondence of which such phenomena occur are low, of the order of 40-60 MeV. A consistent holographic description of in-medium effects on hadron propert…
The recent data for $J/ψ$ hadronic decays from BES raise ``puzzles" about the scalar meson properties, which are different from the naive OZI rule expectation. In this work, we study the implications of a glueball-$Q\bar{Q}$ mixing scheme in the scalar meson productions in $J/ψ$ hadronic decays. We show that the significant OZI violations in $J/ψ\to V f_0^i$ ($i=1,2,3$ correspond to $f_0(1710)$, $f_0(1500)$ and $f_0(1370)$, respectively) are consistent with the requirement of strong glueball-$Q\bar{Q}$ mixings within the scalar meson wavefunctions.
The empirical identification of bound states of gluons has remained a central goal of hadron spectroscopy. We suggest an experimentally challenging, but model--independent way to assess which zero charge, isospin-zero mesons have a large gluonium light-front wavefunction component in the quark and gluon Fock space of QCD. Our method exploits QCD counting rules which relate the power-law fall-off of production amplitudes at high momentum transfer to the meson's twist (dimension minus spin of its minimum interpolating operators). Scalar $0^+$ glueballs composed of two valence gluons with zero in…
Existence of gluonic resonances is among the early expectations of QCD. Today, QCD calculations predict the lightest glueball to be a scalar state with mass within a range of about 900-1700 MeV but there is no consensus about its experimental evidence. In a re-analysis of the phase shifts for pi pi scattering up to 1800 MeV where such states should show up we find the broad resonance f_0(600)/σcontributing to the full mass range and the narrow f_0(980) and f_0(1500) but no evidence for f_0(1370). Phenomenological arguments for the broad state to be a glueball are recalled. It is argued that th…
We calculate the correlation functions of $0^{++}$ $q\bar q$, $s\bar s$ and glueball in the QCD sum rules and obtain the mass matrix where non-diagonal terms are determined by the cross correlations among the three states. Diagonalizing the mass matrix and identifying the eigenstates as the physical $0^{++}$ scalar mesons, we can determine the mixing. Concretely, our calculations determine the fractions of $q\bar q$, $s\bar s$ and glueball in the physical states $f_0(1370)$, $f_0(1500)$ and $f_0(1710)$, the results are consistent with that gained by the phenomenological research.
We consider the two-flavor version of the extended linear sigma model (eLSM), which contains (pseudo)scalar and (axial-)vector quark-antiquark mesons, a scalar glueball (predominantly corresponding to $f_{0}(1710)$), as well as the nucleon and its chiral partner. We extend this model by the additional light scalar meson $f_{0}(500)$, predominantly a putative four-quark state. We investigate various interaction terms of the four-quark and glueball states with the other particles, some of which preserve and some of which explicitly break the $U(1)_{\textrm{A}}$ symmetry. We test our model by per…
We analyze the f_0(1810) state recently observed by the BES collaboration via radiative J/ψdecay to a resonant ϕωspectrum and confront it with DM2 data and glueball theory. The DM2 group only measured ωωdecays and reported a pseudoscalar but no scalar resonance in this mass region. A rescattering mechanism from the open flavored KKbar decay channel is considered to explain why the resonance is only seen in the flavor asymmetric ωϕbranch along with a discussion of positive C parity charmonia decays to strengthen the case for preferred open flavor glueball decays. We also calculate the total glu…
We develop an inverse matrix method to solve for resonance masses from a dispersion relation obeyed by a correlation function. Given the operator product expansion (OPE) of a correlation function in the deep Euclidean region, we obtain the nonperturbative spectral density, which exhibits resonance structures naturally. The value of the gluon condensate in the OPE is fixed by producing the $ρ$ meson mass in the formalism, and then input into the dispersion relations for the scalar, pseudoscalar and tensor glueballs. It is shown that the low-energy limit of the correlation function for the scala…
We compute from lattice QCD in the valence (quenched) approximation the partial decay widths of the lightest scalar glueball to pairs of pseudoscalar quark-antiquark states. These predictions and values obtained earlier for the scalar glueball's mass are in good agreement with the observed properties of $f_J(1710)$ and inconsistent with all other observed meson resonances.
We study the phenomenology of the ground-state (pseudo-)scalar charmonia $η_c$ and $χ_{c0}$ in the framework of a $U(4)_r \times U(4)_l$ symmetric linear sigma model with (pseudo-)scalar and (axial-) vector mesons. Based on previous results for the spectrum of charmonia and the spectrum and (OZI-dominant) strong decays of open charmed mesons, we extend the study of this model to OZI-suppressed charmonia decays. This includes decays into 'ordinary' mesons but also particularly interesting channels with scalar-isoscalar resonances $f_0(1370),\, f_0(1500),\, f_0(1710)$ that may include sizeable c…
The employment of interpolating currents of existed studies of four-quark state and glueball with QCD sum rule approach is analyzed. In terms of suitable currents, the masses of the lowest lying scalar and pseudo-scalar glueball were determined. The masses of some tetraquark states and their first orbital excitations were obtained through a combination of the sum rule with the constituent quark model. Exotica possibility of the new observations by BES is discussed.
We present a two-flavour linear sigma model with global chiral symmetry and (axial-)vector mesons as well as an additional glueball degree of freedom. We study the structure of the well-established scalar resonances f0(1370) and f0(1500): by a fit to experimentally known decay widths we find that f0(1370) is predominantly a \bar{q}q state and f0(1500) is predominantly a glueball state. The overall phenomenology of these two resonances can be well described. Other assignments for our mixed quarkonium-glueball states are also tested, but turn out to be in worse agreement with the phenomenology. …
Scalar glueball is implemented in single nonet linear sigma model (SNLSM) which basically includes lowest lying scalar and pseudoscalar mesons. Our new version of SNLSM involves mixing among scalar matter fields and glueball field which is enforced by scale symmetry considerations and the associated anomaly. Performing iterative Monte Carlo simulations, it is found that among the three candidates of scalar glueball, i.e., $f_0(1370)$, $f_0(1500)$ and $f_0(1710)$, only $f_0(1500)$ is predominately a glueball state with the mass prediction of $1.566 \pm 0.046$ GeV and the other two are predomina…
We estimate the I=0 scalar meson sigma/f_0(600) parameters from pi-pi and gamma-gamma scattering data below 700 MeV using an improved analytic K-matrix model. A fit of the hadronic data gives a complex pole mass M_sigma= 422-i290 MeV, while simultaneous best fits of the gamma-gamma to pi+pi-, pi0pi0 data give a direct width of (0.13+-0.05)keV, a rescattering component of (2.7+-0.4)keV and a total (direct+rescattering) width of (3.9+-0.6)keV. "Running" these results to the physical real axis, the small "direct" gamma-gamma and the large hadronic widths at the "on-shell" mass are compatible with…
The holographic Witten-Sakai-Sugimoto model is an almost parameter-free approximation to large-N QCD with chiral quarks that in a number of cases gives surprisingly good quantitative results for light meson physics. It also allows for predictions of the decay rates of glueballs into pseudoscalar and vector mesons through the coupling of modes on the flavor branes to the massive gravitational modes in the bulk. Including effects from finite quark masses leads to an enhancement of the decay of scalar glueballs into heavier pseudoscalars in good agreement with the decay pattern observed for the s…
Central exclusive diffractive (CED) production of meson resonances potentially is a factory producing new particles, in particular a glueball. The produced resonances lie in trajectories with vacuum quantum numbers, essentially on the pomeron trajectory. A tower of resonance recurrences, the production cross section and the resonances widths are predicted. A new feature is the form of the non-linear pomeron trajectory, producing resonances (glueballs) with increasing widths. At LHC energies, in the nearly forward direction the $t$-channel both in elastic, single or double diffraction dissociat…
