Related papers: Scalar Gluonium and Instantons
The correlator of the square of the Yang-Mills field-strength tensor corresponds to a scalar glueball, i.e., to a bound-state formed by gluonic ingredients only. It has quantum numbers 0++ and its mass, as predicted by different theoretical…
We study the strong and electromagnetic decay properties of scalar mesons above 1 GeV within a chiral approach. The scalar-isoscalar states are treated as mixed states of quarkonia and glueball configurations. A fit to the experimental mass…
In this letter we evaluate one-loop all-plus gluon amplitudes of $\mathrm{SU}(N_c)$ gauge theory with $N_f$ fundamental fermions in the presence of a flavour instanton background. Fermion zero modes are regulated with a chiral mass term.…
We study the mixing structure of isospin-singlet scalars, the light quarkonium $(\bar{q}q)$ and glueball $(gg)$ in two-flavor QCD, based on a holographic model of bottom-up hard-wall type. In the model the pure quarkonium and glueball…
The lattice data on the instanton size distribution suggest an additional O($\rho^2)$ action. The small-$\rho$ effect O($\rho^4)$ predicted by the Operator Product Expansion (OPE) is not observed. Similar deviations are also found for…
The confinement mechanism in the nonperturbative QCD is studied in terms of topological excitation as QCD-monopoles and instantons. In the 't Hooft abelian gauge, QCD is reduced into an abelian gauge theory with monopoles, and the QCD…
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…
String instanton effects in Higgs physics are discussed through a type IIA model based on T^{6}/(Z^{2}\times Z^{'2}) orentifold compactifaction. By inclusion of rigid E2-branes, the model exhibits a MSSM-like spectrum, as well as extra mu…
The isosinglet scalar mesons $f_0(1710)$, $f_0(1500)$, $f_0(1370)$ and their mixing are studied. We employ two recent lattice results as the starting point; one is the isovector scalar meson $a_0(1450)$ which displays an unusual property of…
We study instanton effects on $B \rightarrow X_s\gamma$ decay using the heavy quark effective field theory and the operator product expansion. In the dilute gas approximation the effect is negligibly small. This is in contrast to the result…
We study the role of semi-classical QCD vacuum solutions in high energy scattering by considering the instanton contribution to hadronic cross sections. We propose a new type of instanton-induced interactions (``instanton ladder'') that…
We briefly report on the contribution of QCD-instantons to the phenomenon of saturation in deep-inelastic scattering (DIS) at small Bjorken-x. The explicitly known instanton gauge field serves as a concrete realization of an underlying…
We evaluate a number of new instanton-induced phenomena in QCD, starting with static dipole-dipole potentials, and proceeding to quark-quark and dipole-dipole scattering at high energy. We use a non-perturbative formulation of the…
We report on the interesting possibility of instanton-driven gluon saturation in lepton-nucleon scattering at small Bjorken-x. The explicitly known instanton gauge field serves as a concrete realization of an underlying non-perturbative…
Instanton liquid model being effective model of the QCD vacuum describes well the hadrons at low as well at intermediate energies. Thus, contact with perturbative QCD results is possible providing the unique information about the…
A phenomenological analysis of the scalar glueball and scalar meson spectra is carried out by using the AdS/QCD framework in the bottom-up approach. The resulting spectra are in good agreement for glueballs with lattice QCD results and for…
Axions play a central role in inflationary model building and other cosmological applications. This is mainly due to their flat potential, which is protected by a global shift symmetry. However, quantum gravity is known to break global…
We revisit, scrutinize, improve, confirm and complete our previous results [1-3] from the scalar di-gluonium sum rules within the standard SVZ-expansion at N2LO without instantons and beyond the minimal duality ansatz : "one resonance + QCD…
The instanton contribution to the quark distribution functions in the nucleon is estimated. It is shown, that taking into account the instanton induced interaction between quarks allows to explain the anomalous violation of the Ellis-Jaffe…
We investigate the role of gauge and gravitational instantons in the context of the Swampland program. Our focus is on the global symmetry breaking they induce, especially in the presence of fermions. We first recall and make more precise…