10 pages, 1 figure; talk presented at "Particle Physics, Astrophysics and Quantum Field Theory: 75 Years since Solvay", November 27-29, 2008, Singapore
We employ two simple and robust results to constrain the mixing matrix of the isosinglet scalar mesons $f_0(1710)$, $f_0(1500)$, $f_0(1370)$: one is the approximate SU(3) symmetry empirically observed in the scalar sector above 1 GeV and confirmed by lattice QCD, and the other is the scalar glueball mass at 1710 MeV in the quenched approximation. In the SU(3) symmetry limit, $f_0(1500)$ becomes a pure SU(3) octet and is degenerate with $a_0(1450)$, while $f_0(1370)$ is mainly an SU(3) singlet with a slight mixing with the scalar glueball which is the primary component of $f_0(1710)$. These features remain essentially unchanged even when SU(3) breaking is taken into account. The observed enhancement of $ωf_0(1710)$ production over $ϕf_0(1710)$ in hadronic $J/ψ$ decays and the copious $f_0(1710)$ production in radiative $J/ψ$ decays lend further support to the prominent glueball nature of $f_0(1710)$. We deduce the mass of the pseudoscalar glueball $G$ from an $η$-$η'$-$G$ mixing formalism based on the anomalous Ward identity for transition matrix elements. With the inputs from the recent KLOE experiment, we find a solution for the pseudoscalar glueball mass around $(1.4\pm 0.1)$ GeV, which is fairly insensitive to a range of inputs with or without Okubo-Zweig-Iizuka-rule violating effects. This affirms that $η(1405)$, having a large production rate in the radiative $J/ψ$ decay and not seen in $γγ$ reactions, is indeed a leading candidate for the pseudoscalar glueball. It is much lower than the results from quenched lattice QCD ($>2.0$ GeV) due to the dynamic fermion effect. It is thus urgent to have a full QCD lattice calculation of pseudoscalar glueball masses.
We deduce the mass of the pseudoscalar glueball $G$ from an $η$-$η'$-$G$ mixing formalism based on the anomalous Ward identity for transition matrix elements. With the inputs from the recent KLOE experiment, we find a solution for the pseudoscalar glueball mass around $(1.4\pm 0.1)$ GeV, which is fairly insensitive to a range of inputs with or without Okubo-Zweig-Iizuka-rule violating effects. This affirms that $η(1405)$, having a large production rate in the radiative $J/Ψ$ decay and not seen in $γγ$ reactions, is indeed a leading candidate for the pseudoscalar glueball. Other relevant quanti…
We introduce a parametrization scheme for $J/ψ(ψ^\prime)\to VP$ where the effects of SU(3) flavor symmetry breaking and doubly OZI-rule violation (DOZI) can be parametrized by certain parameters with explicit physical interpretations. This scheme can be used to clarify the glueball-$q\bar{q}$ mixing within the pseudoscalar mesons. We also include the contributions from the electromagnetic (EM) decays of $J/ψ$ and $ψ^\prime$ via $J/ψ(ψ^\prime)\to γ^*\to VP$. Via study of the isospin violated channels, such as $J/ψ(ψ^\prime)\to ρη$, $ρη^\prime$, $ωπ^0$ and $ϕπ^0$, reasonable constraints on the E…
A new meson mass relation for meson nonet is given after considering mixing with glueball. The mixing between pseudoscalar mesons and pseudoscalar glueball will decrease the mass of glueball by about 500 Mev. So, according to the predicted mass of the pure pseudoscalar glueball given by lattice calculation and effective Hamiltonian, the expected mass of mixed pseudoscalar glueball is about 1.7 Gev. This result is helpful for experimemtal search for the mixed Isoscalar pseudoscalar glueball.
We expand the study of the pseudoscalar glueball and its first excited state by constructing an interaction Lagrangian which produces the two- and three-body decays of the pseudoscalar glueball, $J^{PC}=0^{-+}$, into the (pseudo)scalar and the excited (pseudo)scalar mesons as well as by constructing other two different chiral Lagrangians which describe the two- and three-body decays of the first excited pseudoscalar glueball, $J^{PC}=0^{*-+}$, into the (pseudo)scalar and the excited (pseudo)scalar mesons. We compute the decay channels for the ground state of a pseudoscalar glueball with a mass…
We study three different chiral Lagrangians that describe the two- and three-body decays of an excited pseudoscalar glueball, $J^{PC}=0^{*-+}$, into light mesons and charmonium states as well as into a scalar and pseudoscalar glueball. We compute the decay channels for an excited pseudoscalar glueball with a mass of $3.7$ GeV and consider a ground state pseudoscalar glueball of mass $2.6$ GeV, following predictions from lattice QCD simulations. These states and channels are in reach of the ongoing BESIII experiment and the PANDA experiments at the upcoming FAIR facility experiment. We present …
The supernumerous eta(1405) is considered a strong candidate for the pseudoscalar glueball. In a phenomenological chiral approach, we consider a mixing scenario of bare pseudoscalar (n bar n) and (s bar s) quarkonia with the glueball. We study the decay properties and point out the peculiarities of this scenario in order to support the possible identification of the J(PC) = 0(-+) glueball.
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. …
We study whether the pseudoscalar glueball mass in full QCD can differ from the prediction of quenched lattice calculations. Using properties of the correlator of the vacuum topological susceptibility we derive an expression for the upper bound on the QCD glueball mass. We show that the QCD pseudoscalar glueball is lighter than the pure Yang-Mills theory glueball studied in quenched lattice calculations. The mass difference between those two states is of order of $1/N_c$. The value calculated for the $0^{-+}$ QCD glueball mass can not be reconciled with any physical state observed so far in th…
We calculate the branching ratios of the lightest pseudoscalar glueball with a mass of 2.6 GeV predicted by lattice QCD by using a chiral Lagrangian. This study is relevant in view of the planned PANDA experiment at the upcoming FAIR facility, which will measure the energy range in which the pseudoscalar glueball is predicted to exist.
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.
We study a chiral Lagrangian which describes the two- and three-body decays of a pseudoscalar glueball into scalar and pseudoscalar mesons. The various branching ratios are a parameter-free prediction of our approach. We compute the decay channels for a pseudoscalar glueball with a mass of 2.6 GeV, as predicted by Lattice QCD in the quenched approximation, which is in the reach of the PANDA experiment at the upcoming FAIR facility. For completeness, we also repeat the calculation for a glueball mass of 2.37 GeV which corresponds to the mass of the resonance X(2370) measured in the BESIII exper…
We have performed a dynamical analysis of the mixing in the pseudoscalar channel with the goal of understanding the existence and behavior of the pseudoscalar glueball. Our philosophy has not been to predict precise values of the glueball mass but to exploit an adequate effective theory to the point of breaking and to analyze which kind of mechanisms restore compatibility with data. Our study has lead to analytical solutions which allow a clear understanding of the phenomena. The outcome of our calculation leads to a large mass glueball $M_Θ>2000$ MeV, to a large glue content of the $η^\prime$…
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…
We study the interactions of the pseudoscalar glueball with scalar and pseudoscalar quark-antiquark meson fields and with the nucleon and its chiral partner. In both cases we introduce the corresponding chiral Lagrangian and discuss its properties. We calculate the mesonic and baryonic decays of a pseudoscalar glueball with mass of about 2.6 GeV as predicted by Lattice simulations.
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…
The lowest scalar and pseudoscalar glueball masses are evaluated by means of the time-dependent variational approach to the Yang-Mills gauge theory without fermions in the Hamiltonian formalism within a Gaussian wavefunctional approximation. The glueball mass is calculated as a pole of the propagator for a composite glueball field which consists of two massless gluons. The glueball propagator is here evaluated by using the linear response theory for the composite external glueball field. As a result, a finite glueball mass is obtained through the interaction between two massless gluons, in whi…
Topological charge screening in the QCD vacuum is found to provide crucial nonperturbative contributions to the short-distance expansion of the pseudoscalar (0^{-+}) glueball correlator. The screening contributions enter the Wilson coefficients and are an indispensable complement to the direct instanton contributions. They restore consistency with the anomalous axial Ward identity and remedy several flaws in the 0^{-+} glueball sum rules caused by direct instantons in the absence of screening (lack of resonance signals, violation of the positivity bound and of the underlying low-energy theorem…
We study the pseudoscalar glueball candidates in a chiral effective Lagrangian model proposed by 't hooft, motived by taking into account the instanton effects, which can describe not only the chiral symmetry breaking, but also the solution of $U_A(1)$. We study the parameter space allowed by constraints from vacuum conditions and unitary bounds. By considering two scenarios in $0^{++}$ sector, we find that parameter space which can accommodate the $0^{-+}$ sector is sensitive to the conditions in $0^{++}$ sector. From our analysis, it is found that three $η$ states, i.e. $η(1295)$, $η(1405)$,…
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…
Using two simple and robust inputs to constrain the mixing matrix of the isosinglet scalar mesons $f_0(1710)$, $f_0(1500)$, $f_0(1370)$, we have shown that in the SU(3) symmetry limit, $f_0(1500)$ becomes a pure SU(3) octet and is degenerate with $a_0(1450)$, while $f_0(1370)$ is mainly an SU(3) singlet with a slight mixing with the scalar glueball which is the primary component of $f_0(1710)$. These features remain essentially unchanged even when SU(3) breaking is taken into account. We have deduced the mass of the pseudoscalar glueball $G$ from an $η$-$η'$-$G$ mixing formalism based on the a…
A generalization of the chiral effective lagrangian of order $p^2$ is proposed which involves the $η'$-meson, its excitation, and the pseudoscalar (PS) glueball. Model-independent constraints are found for the contributions to the lagrangian of the above singlet states. Those allow one to independently identify the nature of these singlet states in the framework of the approach. The mixing among the iso-singlet states (including $η^8$-state) is analysed, and the hierarchy of the mixing angles is described which is defined by the chiral and large-$N_c$ expansions. The recent PCAC results are re…
In the framework of the so-called extended linear sigma model (eLSM), we include a pseudoscalar glueball with a mass of 2.6 GeV (as predicted by Lattice-QCD simulations) and we compute the two- and three-body decays into scalar and pseudoscalar mesons. This study is relevant for the future PANDA experiment at the FAIR facility. As a second step, we extend the eLSM by including the charm quark according to the global $U(4)_R \times U(4)_L$ chiral symmetry. We compute the masses, weak decay constants and strong decay widths of open charmed mesons. The precise description of the decays of open ch…
An effective chiral lagrangian of order $p^2$, describing the interaction of light pseudoscalar (PS) mesons with $η'$-meson and PS-glueball, has been determined taking into consideration the renorm-group requirements imposed by QCD renormalization. It is shown that the interpolating fields for the lowest singlet quarkic and gluonic states, $η^0$ and $η^G$, may be involved into the effective theory to be renorm-invariant objects not mixing due to QCD renormalization. It is established that the potential describing the ``mass'' term of the lagrangian does not depend on $η^0$. The dependence on $…
We revisit the $U(1)_A$ anomaly in the holographic model of low-energy QCD by Witten, Sakai, and Sugimoto, presenting a new and direct derivation of the Witten-Veneziano mechanism for generating the mass of the $η'$ through an anomalous mixing of the Ramond-Ramond $C_1$ field with the singlet component of the pseudoscalar mesons. The latter turns out to have a kinetic mixing with the normalizable modes of the $C_1$ field representing pseudoscalar glueballs, yielding additional vertices for their production and their decay that dominate over those of the unmixed case considered previously in th…
The top-down holographic Witten-Sakai-Sugimoto model for low-energy QCD, augmented by finite quark masses, has recently been found to be able to reproduce the decay pattern of the scalar glueball candidate f0(1710) on a quantitative level. In this Letter we show that this model predicts a narrow pseudoscalar glueball heavier than the scalar glueball and with a very restricted decay pattern involving eta or eta' mesons. Production should be either in pairs or in association with eta(') mesons. We discuss the prospect of discovery in high-energy hadron collider experiments through central exclus…
The pseudoscalar mesons with the masses higher than 1 GeV are assumed to belong to the meson decuplet including the glueball as the basis state supplementing the standard $SU(3)_F$ nonet of light $q\bar{q}$ states $(u,d,s)$. The decuplet is investigated by means of an algebraic approach based on hypothesis of vanishing the exotic $SU(3)_F$ commutators of "charges" and their time derivatives. These commutators result in a system of equations determining contents of the isoscalar octet state in the physical isoscalar mesons as well as the mass formula including all masses of the decuplet: $π(130…
The Witten-Sakai-Sugimoto model, a top-down gauge/gravity model of large-$N_c$ low-energy QCD based on type-IIA string theory and $N_c$ D4 branes with chiral quarks added by probe D8 branes, involves only one dimensionless parameter, the 't Hooft coupling at its cutoff (Kaluza-Klein) scale. Although this cutoff scale is around 1 GeV, the model has turned out to be surprisingly predictive also quantitatively, reproducing masses of vector and axial vector mesons, their decay rates, as well as the anomalous mass of the η' meson, all within 10-30% errors. Using it as a guide for glueball signature…
We discuss the $0^{+-}$ singlet sector of glueballs in the Klebanov-Strassler theory. We report the results of a numerical study of the linearized equations in the Klebanov-Strasller background and make a comparison with the spectrum of the scalar sector. While for four towers of the total six towers of massive pseudoscalar states our results match the spectrum of the corresponding towers of scalars, the values for the remaining two towers diverge with those of the scalars. We discuss possible interpretations of this divergence.
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 consider the parity doublet structure observed in high hadronic excitations within the instanton model for the QCD vacuum. In the conventional approach this doubling phenomenon is treated as a manifestation of the partial restoration of chiral or $U(1)_A$ symmetry. We demonstrate that the suppression of direct instanton contribution to the masses of excited hadrons leads to the partial $U(1)_A$ symmetry restoration in hadron spectrum. The origin of X(1835) resonance observed by BES Collaboration is studied upon the doublet structure. We argue also how X(1835) be interpreted as the lowest ps…
Discussed is how non-perturbative properties of quark gluon plasma, recently discovered in RHIC experiment, can be related to the change of properties of scalar and pseudoscalar glueballs. We set up a model with the Cornwall-Soni's glueball-gluon interaction, which shows that the pseudoscalar glueball becomes massless above the critical temperature of deconfinement phase transition. This change of properties gives rise to the change of sign of the gluon condensate at $T > T_c$. We discuss the other physical consequences resulting from the drastic change of the pseudoscalar glueball mass above …
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…
In this paper we describe a pseudoscalar subsector of the Klebanov-Strassler model. This subsector completes the holographic reconstruction of the spectrum of the lowest-lying glueball states, which are singlet under the global symmetry group $SU(2)\times SU(2)$. We derive the linearized supergravity equations for the pseudoscalar fluctuations and analyze their spectrum. The system of equation is shown to be compatible with six eigenmodes, as expected from supersymmetry. Our numerical analysis allows to reliably extract four of the corresponding towers. Their values match well the eigenvalues …
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…
We consider the dynamics of the scalar and pseudoscalar glueballs in the Quark-Gluon Plasma (QGP). By using the instanton model for the QCD vacuum we give the arguments that the nonperturbative gluon-gluon interaction is qualitatively different in the confinement and deconfinement phases. Based on this observation it is shown that above $T_c$ the values of the scalar and pseudoscalar glueball masses might be very small. The estimation of the temperature of scale invariance restoration, at which the scalar glueball becomes massless, is given. We also discuss the Bose-Einstein condensation of th…
We evaluate the coupling constant for the lightest scalar glueball to decay to pseudoscalar meson pairs. The calculation is done in the valence approximation on a $16^3 \times 24$ lattice at $β= 5.70$ for two different values of pseudoscalar meson mass.
Here we analyse the low energy confining phase of the $2+1$ dimensional quenched QCD-like theory in anisotropic non-supersymmetric D$2$ brane background with the holographic approach. Two key features of QCD -- flux-tube tension and mass spectrum of pseudoscalar glueball are studied. The non-supersymmetric D$2$ branes with anisotropy in time direction are considered as the gravity theory. Tuning the anisotropic parameter, we get the Hawking-Page transition in the gravity background. On the dual theory, this refers the confinement-deconfinement phase transition. Using the Wilson loop, the linea…
We generalize the dispersive approach to axial anomaly by A.D. Dolgov and V.I. Zakharov to a non-Abelian case with arbitrary photon virtualites. We derive the anomaly sum rule for the singlet current and obtain the $π^0,η,η'\rightarrowγγ^*$ transition form factors. Using them, we established the behavior of a nonperturbative gluon matrix element $\langle 0 |G\tilde{G} |γγ^*(q^2) \rangle$ in both spacelike and timelike regions. We found a significant contribution of the non-Abelian axial anomaly to the processes with one virtual photon, comparable to that of the electromagnetic anomaly. The dua…
We provide results for the spectrum of scalar and pseudoscalar glueballs in pure Yang-Mills theory using a parameter-free fully self-contained truncation of Dyson-Schwinger and Bethe-Salpeter equations. The only input, the scale, is fixed by comparison with lattice calculations. We obtain ground state masses of $1.9\,\text{GeV}$ and $2.6\,\text{GeV}$ for the scalar and pseudoscalar glueballs, respectively, and $2.6\,\text{GeV}$ and $3.9\,\text{GeV}$ for the corresponding first excited states. This is in very good quantitative agreement with available lattice results. Furthermore, we predict ma…
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…
The existence of a glueball has been a tough work for many years study. Utilizing the well developed QCD theory for $B$ meson decays, we propose a new way to identify whether a scalar glueball existed or not. In the presence of mixing between glueballs and ordinary scalar mesons, we explore the possibility to extract the mixing parameters from semileptonic B decays and nonleptonic B decays. We also point out a clean way to identify a glueball through $B_c$ decays.
Ground-state scalar isoscalar mesons and a scalar glueball are described in a U(3)xU(3) chiral quark model of the Nambu--Jona-Lasinio (NJL) type with 't Hooft interaction. The latter interaction produces singlet-octet mixing in the scalar and pseudoscalar sectors. The glueball is introduced into the effective meson Lagrangian as a dilaton on the base of scale invariance. The mixing of the glueball with scalar isoscalar quarkonia and amplitudes of their decays into two pseudoscalar mesons are shown to be proportional to current quark masses, vanishing in the chiral limit. Mass spectra of the sc…
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.
The Kawai model describing the glueball-quarkonia mixing is modified. The mixing of $η$, $η^\prime$ and $η(1410)$ is re-investigated based on the modified Kawai model. The glueball-quarkonia content of the three states is determined from a fit to the data of the electromagnetic decays involving $η$, $η^\prime$. Some predictions about the electromagnetic decays involving $η(1410)$ are presented.
We establish the factorization formula for scalar Glueball production through radiative decays of vector states of heavy quarkonia, e.g. $J/ψ$, $ψ(2S)$ and $Υ(nS)$, where the Glueball mass is much less than the parent heavy quarkonium mass. The factorization is demonstrated explicitly at one-loop level through the next-to-leading order (NLO) corrections to the hard kernel, the non-relativistic QCD (NRQCD) long-distance matrix element (LDMEs) of the heavy quarkonium, and the light-cone distribution amplitude (LCDA) of scalar Glueball. The factorization provides a comprehensive theoretical appro…
Using flavor SU(3) symmetry for the light quarks validated by the available experimental data, we propose an intuitive way to hunt for a scalar glueball in B decays. In the presence of mixing between the glueball and ordinary scalar mesons, we explore the extraction of the mixing parameters. In particular, we discuss the implication from the recently available experimental data and show the sensitivities of B decays as a probe to the scalar structures. The future Super KEKB factory would allow access to establishing the mixing pattern among the scalars, and possibly allow one to disentangle th…
We investigate transition form factors of $B$ meson decays into a scalar glueball in the light-cone formalism. Compared with form factors of $B$ to ordinary scalar mesons, the $B$-to-glueball form factors have the same power in the expansion of $1/m_B$. Taking into account the leading twist light-cone distribution amplitude, we find that they are numerically smaller than those form factors of $B$ to ordinary scalar mesons. Semileptonic $B\to Gl\barν$, $B\to Gl^+l^-$ and $B_s\to Gl^+l^-$ decays are subsequently investigated. We also analyze the production rates of scalar mesons in semileptonic …
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 mixing of $η_c$ and the lowest mass pseudoscalar glueball is estimated within the framework of the instanton liquid model. It is demonstrated that the mixing is large and may explain the difference between the observed mass of the glueball candidate X(1835) and the theoretical prediction of QCD sum rule analysis.
In pure-glue QCD, gluon-gluon scattering in the $J^{PC}=0^{-+}$ channel is described by a very simple equation, especially if one considers just the leading contribution to the scattering kernel. Of all components in this kernel, only the three-gluon vertex, $V_{μνρ}$, is poorly constrained by contemporary analyses; hence, calculations of $0^{-+}$ glueball properties serve as a clear window onto the character and form of $V_{μνρ}$. This is important given that many modern calculations of $V_{μνρ}$ predict the appearance of an infrared suppression in the scalar function which comes to modulate …
Here we study two important properties of $2+1$ dimensional QCD -- confinement and pseudoscalar glueball spectrum -- with holographic approach. We consider the low energy decoupled geometry of the isotropic non-susy D$2$ brane. We find the corresponding gauge theory is similar to the $2+1$-dim Yang-Mills theory with the running coupling $λ^2$. At the extremal limit (i.e. BPS limit), this gauge theory reduces to the super-YM theory. From the Nambu-Goto action of a test string, the potential of a \qq pair located on the boundary is calculated. At large \qq separation it gives the tension $σ$ of …
Glueballs are predicted in various theoretical approaches of QCD (most notably lattice QCD), but their experimental verification is still missing. In the low-energy sector some promising candidate for the scalar glueball exist, and some (less clear) candidates for the tensor and pseudoscalar glueballs were also proposed. Yet, for heavier gluonic states there is much work to be done both from the experimental and theoretical points of view. In these proceedings, we briefly review the current status of research of glueballs and discuss future developments.
Glueballs and fractional anomalous determinants at nonzero $θ$, and the decays of the X(2370)
Jan Kochanowski University（扬·科哈诺夫斯基大学）；Goethe-University（歌德大学）；University of Pittsburgh（匹兹堡大学）；HUN-REN Wigner Research Centre for Physics（匈牙利研究与创新网络维格纳物理研究中心）；University of Wroclaw（弗罗茨瓦夫大学）；Brookhaven National Laboratory（布鲁克海文国家实验室）；Justus Liebig University Giessen（吉森尤斯图斯·李比希大学）；Helmholtz Research Academy Hesse for FAIR (HFHF)（黑森亥姆霍兹FAIR研究院）
We study instanton contributions to hadronic decays of the scalar glueball, the pseudoscalar charmonium state $η_c$, and the scalar charmonium state $χ_c$. Hadronic decays of the $η_c$ are of particular interest. The three main decay channels are $K\bar{K}π$, $ηππ$ and $η'ππ$, each with an unusually large branching ratio $\sim 5%$. On the quark level, all three decays correspond to an instanton type vertex $(\bar{c}c)(\bar{s}s)(\bar{d}d)(\bar{u}u)$. We show that the total decay rate into three pseudoscalar mesons can be reproduced using an instanton size distribution consistent with phenomenol…
Based on the general analysis of branching ratio of two pseudoscalar meson channels, discriminants between mesons and glueballs for $I=0, J^{PC}=even^{++}$ unflavored hadrons with mass between 1.2 GeV and 2.9 GeV are suggested. Known $I=0, J^{PC}=2^{++}, f_2(1525)$ particle is discriminated as a typical meson. The way to discriminate new $I=0, J^{PC}=even^{++}$ unflavored hadrons is discussed.
