Vector Glueball Research Articles

Spin-1 glueballs in the Witten-Sakai-Sugimoto model

We consider the vector and the pseudovector glueball in the top-down holographic model of large-Nc QCD of Witten and their decays into ordinary mesons described by the D8 brane construction due to Sakai and Sugimoto. At leading order, the relevant interactions are determined exclusively by the Chern-Simons action of the D8 branes and are thus rigidly connected to the chiral anomaly and the Wess-Zumino-Witten terms. As found in a previous study of the pseudovector glueball, which we revisit and complete, the resulting decay widths are surprisingly large, implying that both the pseudovector and the vector glueball are very broad resonances, with a conspicuous dominance of decays into a1ρ and K1(1400)K* in the case of the vector glueball. We also obtain a certain weak mixing of vector glueballs with ordinary vector mesons, but we conclude that it does not provide an explanation for the so-called ρπ puzzle in charmonium decays. Published by the American Physical Society 2024

Glueball-meson mixing in holographic QCD

Top-down holographic QCD models often work in the “probe” (or “quenched”) limit, which assumes that the number of colors is much greater than the number of flavors. Relaxing this limit is essential to a fuller understanding of holography and more accurate phenomenological predictions. In this work, we focus on a mixing of glueball and meson mass eigenstates that arises from the DBI action as a finite Nf/Nc effect. For concreteness, we work in the Witten-Sakai-Sugimoto model, and show that this mixing must be treated in conjunction with the backreaction of the flavor branes onto the background geometry. Including the backreaction with the simplification that it is “smeared out” over the compact transverse direction, we derive a corrected effective action for the vector glueball and scalar states. Along the way, we observe a Stückelberg-like mechanism that restores translation invariance in the transverse direction. We also derive a general technique, that lends itself easily to numerics, for finding mass eigenstates of Lagrangians with vector-scalar mixing. We then calculate the first order corrections to the mass spectra of both the vector and scalar particles, and show that the term that explicitly mixes vector and scalar states is the most significant correction to the masses of low-lying scalar mesons.

Decays of the vector glueball

We calculate two- and three-body decays of the (lightest) vector glueball into (pseudo)scalar, (axial-)vector, as well as pseudovector and excited vector mesons\textbf{ }in the framework of a model of QCD. While absolute values of widths cannot be predicted because the corresponding coupling constants are unknown, some interesting branching ratios can be evaluated\textbf{ }by setting the mass of the yet hypothetical vector glueball to $3.8$ GeV as predicted by quenched Lattice QCD\textbf{.} We find that the decay mode $\omega\pi\pi$ should be one of the largest (both through the decay chain $\mathcal{O}\rightarrow b_{1}\pi\rightarrow$ $\omega\pi\pi$ and through the direct coupling $\mathcal{O}\rightarrow\omega\pi\pi$)$.$ Similarly, the (direct and indirect) decay into $\pi KK^{\ast}(892)$ is sizable. Moreover, the decays into $\rho\pi$ and $K^{\ast}(892)K$ are, although subleading, possible and could play a role in explaining the $\rho\pi$ puzzle of the charmonium state $\psi(2S)$ thank to a (small) mixing with the vector glueball. The vector glueball can be directly formed at the ongoing BESIII experiment as well as at the future PANDA experiment at the FAIR facility. If the width is sufficiently small ($\lesssim100$ MeV) it should not escape future detection. It should be stressed that the employed model is based on some inputs and simplifying assumptions: the value of glueball mass (at present, the quenched lattice value is used), the lack of mixing of the glueball with other quarkonium states, and the use of few interaction terms. It then represents a first step toward the identification of the main decay channels of the vector glueball, but shall be improved when corresponding experimental candidates and/or new lattice results will be available.

Dual QCD thermodynamics and quark–gluon plasma

Using grand canonical ensemble formulation of a multi-particle statistical system, the thermodynamical description of dual QCD based on magnetic symmetry has been presented and analyzed for the quark–gluon plasma phase of hadronic matter. The dual QCD based bag construction has been shown to lead to the radial pressure on bag surface in terms of the vector glueball masses of magnetically condensed QCD vacuum. Constructing the grand canonical partition function, the energy density and plasma pressure have been derived and used to compute the critical temperatures for QGP–hadron phase transition along with its dynamics. A comparison of the values of critical temperatures for QGP–hadron phase transition with those obtained for the deconfinement-phase transition, has been shown to lead to either the relaxation of the system via a mixed phase of QGP and hot hadron gas or go through a crossover. The associated profiles of the normalized energy density and specific heat have been shown to lead to a large latent heat generation and indicate the onset of a first-order QGP phase transition which turns into a rapid crossover for the case of temperature dependent bag parameter. The squared speed of sound has been shown to act as a physical measure of large thermodynamical fluctuations near transition point. The possible implications of trace anomaly and conformal measure on QGP formation have also been discussed.

Holographic [formula omitted] Multiplets

In this communication we report on the results of the study of the holographic dual for the anomaly and gravity N = 1 multiplets in the baryonic branch generalization of the Klebanov-Strassler background. We present the equation for the transverse vector glueball in KS case. The spectrum of low lying excitations coincides with the spectrum of the traceless graviton. The anomalous longitudinal part of the the current is degenerate with the scalar glueball, that is a perturbation of the trace of the metric. The latter glueballs are lighter than the gravity multiplet everywhere on baryonic branch.

On the light glueball spectrum in a holographic description of QCD

We investigate the spectra of light scalar and vector glueballs in a holografic description of QCD with a dilaton background bulk field. In particular, we study how the glueball masses depend on the conditions on the dilaton background and on the geometry of the bulk.

An alternative interpretation of X(3872)

It is proposed that X(3872) is a vector glueball mixed with neighboring vector states of charmonium.

COLOR CONFINEMENT AND FINITE TEMPERATURE QCD PHASE TRANSITION

We study an effective theory of QCD in which the fundamental variables are dual magnetic potentials coupled to the monopole field. Dual dynamics are then used to explain the properties of QCD vacuum at zero temperature as well as at finite temperatures. At zero temperature, the color confinement is realized through the dynamical breaking of magnetic symmetry, which leads to the magnetic condensation of QCD vacuum. The flux tube structure of SU(2) QCD vacuum is investigated by solving the field equations in the low energy regimes of the theory, which guarantees dual superconducting nature of the QCD vacuum. The QCD phase transition at finite temperature is studied by the functional diagrammatic evaluation of the effective potential on the one-loop level. We then obtained analytical expressions for the vacuum expectation value of the condensed monopoles as well as the masses of glueballs from the temperature dependent effective potential. These nonperturbative parameters are also evaluated numerically and used to determine the critical temperature of the QCD phase transition. Finally, it is shown that near the critical temperature (Tc≃0.195 GeV ), continuous reduction of vacuum expectation value (VEV) of the condensed monopoles caused the disappearance of vector and scalar glueball masses, which brings a second order phase transition in pure SU(2) gauge QCD.

Elusive vector glueball

If the vector glueball exists in the mass range that theory suggests, its resonance production cross section can be seen in e+e- annihilation only if the decay width is very narrow (< a few MeV). Otherwise it willbe observed only indirectly through its mixing with psi(2S). A few tests of the glueball-psi' mixing are proposed for future charm factories.

On the mixing amplitude of [formula omitted] and vector glueball O

We study the mixing angle θ Oψ and mixing amplitude f Oψ of J ψ and vector glueball O based on the framework of potential models of heavy quarks and constituent gluons. While the state vectors of J ψ and O are constructed from the wave functions of fewbody Schroedinger equations, the mixing dynamics is governed by perturbative QCD. We obtain a value of the mixing angle of |tan θ Oψ | ≈ 0.015 and the mixing amplitude of | f Oψ ( m Oψ 2)| ≈ 0.008 GeV 2. Within our approximation scheme, this result is comparable with phenomenological analysis.

Erratum: Search for a vector glueball by a scan of theJ/ψresonance [Phys. Rev. D 54, 1221 (1996)

Erratum: Search for a vector glueball by a scan of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>J</mml:mi><mml:mo>/</mml:mo><mml:mi>ψ</mml:mi></mml:math>resonance [Phys. Rev. D 54, 1221 (1996)

Glueballs: Charmonium decay andp¯pannihilation

The vector glueball $O$, made of 3 valence gluons, is expected to be ``clean": it mixes less with quarkonia, but mediates OZI violations. The recent $0^{++} $ glueball candidate and the persistence of the $J/\psi, \psi' \to \rho\pi$ puzzle suggest $m_O\simeq m_{J/\psi}$, with mixing angle $\sim 2^\circ - 4^\circ$, hence $\Gamma(O\to \rho\pi$, $K^+K^-$, $e^+e^-) \sim$ MeV, few keV, few eV. Lower and upper bounds on $\Gamma_O$ can be argued from $e^+e^- \to \rho\pi$ energy scan data and the condition $B(O\to \rho\pi) > B(J/\psi\to \rho\pi)$. $O$ dominance may explain the ``large" OZI violation in $^1S_0(\bar pp)\to \phi\gamma$ vs. $\omega\gamma$.

Search for a vector glueball by a scan of the J/ psi resonance.

The cross section for {ital e}{sup +}{ital e}{sup {minus}}{r_arrow}{rho}{pi} has been measured by the BES detector at BEPC at center-of-mass energies covering a 40 MeV interval spanning the {ital J}/{psi} resonance. The data are used to search for the vector gluonium state hypothesized by Brodsky, Lepage, and Tuan as an explanation of the {rho}{pi} puzzle in charmonium physics. The shape of the {rho}{pi} cross section is compatible with that of the total hadronic cross section. No distortions indicating the presence of a vector glueball are seen. {copyright} {ital 1996 The American Physical Society.}

Vector resonances and electromagnetic nucleon structure.

Motivated by new, precise magnetic proton form factor data in the timelike reigon, a hybrid vector meson dominance (hVMD) formalism is employed to investigate the significance of excited vector meson rsonances on electromagnetic nucleon structure. We find that the \ensuremath{\rho}(1700), \ensuremath{\omega}(1600), and two previously unobserved states are required to reproduce the local structure seen in the new LEAR data just above the pp\ifmmode\bar\else\textasciimacron\fi{} threshold. We also investigate sensitivity to the \ensuremath{\varphi} meson. The model dependence of our result is tested by introducing an alternative model which couples the isoscalar vector meson states to a hypothetical vector glueball resonance. We obtain nearly identical results from both models, except for ${\mathit{G}}_{\mathit{E}}^{\mathit{n}}$(${\mathit{q}}^{2}$) in the spacelike region which is very sensitive to the glueball mass and the effective \ensuremath{\varphi}NN coupling.

Determination of the mass of the 1– – vector glueball from quantum chromodynamics sum rule

We analyse the influence of continuum corrections over the quantum chromodynamics sum rule for the 1– – three-gluon conserved current. The mass of the 1– – vector glueball is determined to be 2.4 GeV. It should be noted that this mass value does not sensitively depend on the choice of the combination of the two independent currents.

The vector glueball and its Quantum Chromodynamics sum rule

A gauge invariant and Lorentz-irreducible three-gluon conserved vector current is constructed, and the mass of the vector glueball is calculated in the framework of the Quantum Chromodynamics sum rules.

The vector glueball: An algebraic approach.

The ${J}^{\mathrm{PC}}$${=1}^{\mathrm{\ensuremath{-}}\mathrm{\ensuremath{-}}}$ vector glueball is considered in addition to the usual ${\mathrm{SU}}_{\mathrm{F}}$(4) multiplet consisting of \ensuremath{\rho}, ${K}^{\mathrm{*}}$, \ensuremath{\omega}, \ensuremath{\varphi}, ${D}^{\mathrm{*}}$, ${F}^{\mathrm{*}}$, and J/\ensuremath{\psi} using an algebraic approach consistent with QCD. We calculate the glueball mass to be \ensuremath{\simeq}1.75 GeV and its width to be \ensuremath{\gtrsim}3 MeV. It mixes substantially with J/\ensuremath{\psi}. The vector glueball decays copiously into \ensuremath{\rho}\ensuremath{\pi} and ${K}^{\mathrm{*}}$K\ifmmode\bar\else\textasciimacron\fi{} when compared to its decay into KK\ifmmode\bar\else\textasciimacron\fi{}. The \ensuremath{\Delta}I=1 isovector radiative decays of the vector mesons are predicted. In addition \ensuremath{\Gamma}(${K}^{\mathrm{*}0}$\ensuremath{\rightarrow}${K}^{0}$+\ensuremath{\gamma}) is predicted to be 138 keV. We neglect intermultiplet mixing.

Gluonium states and νc→λX

The effects of gluonium states on νc(2980)→λX are discussed. In order to examine the properties of vector glueball, measurements of the inclusive γ spectrum in νc→λX or those of the $$\rho \pi \left( {\bar KK^* } \right)$$ mass distributions in $$\eta _c \to \gamma \rho \pi \left( {\eta _c \to \gamma \bar KK^* } \right)$$ are suggested.

Vector Gluonium as a Possible Explanation for AnomalousψDecays

Recent experiments at SLAC show unexpectedly large values for the ratios (1) $\frac{B(\ensuremath{\psi}\ensuremath{\rightarrow}\ensuremath{\rho}\ensuremath{\pi})}{B({\ensuremath{\psi}}^{\ensuremath{'}}\ensuremath{\rightarrow}\ensuremath{\rho}\ensuremath{\pi})}$ and (2) $\frac{B(\ensuremath{\psi}\ensuremath{\rightarrow}{K}^{*}\overline{K})}{B({\ensuremath{\psi}}^{\ensuremath{'}}\ensuremath{\rightarrow}{K}^{*}\overline{K})}$. It is proposed that these anomalies are caused by the mixing of the ground-state isoscalar vector mesons ($\ensuremath{\omega}, \ensuremath{\phi}, \ensuremath{\psi}$) with a ${J}^{\mathrm{PC}}={1}^{\ensuremath{-}\ensuremath{-}}$ vector glueball ($O$) which was first postulated by Freund and Nambu in 1975. Its mass is estimated at \ensuremath{\simeq} 2.4 GeV and direct experimental searches for the $O$ are suggested.

A basic guide for the glueball spotter

After a brief review of the theoretical and phenomenological motivation for the existence of gluonic resonances, we examine the expected properties of such states, and consider possible tests for their presence in the hadronic spectrum below 1.5 GeV in mass. The scalar mesons can be classified as an approximately ideally mixed nonet with an additional isoscalar, the S ∗, with all the expected properties of a scalar glueball. It is suggested that the η′ contains a large proportion of glue as well as strange quarks and that, if the E(1420) is not a pseudoscalar, two further pseudoscalars await discovery in the low-lying meson spectrum. The pomeron, a narrow resonance in the ππ D-wave, must be found with a mass around or slightly below that of the S ∗. If the pomeron has a daughter vector glueball which, as has been argued, is fairly close to the φ mass, then it should also have a mother 3 −− glueball with a similar mass. The D(1285) may well be a 2 −+ glueball.