Related papers: Instantons and Meson Correlators in QCD
Taking the gauge invariant quark correlator as an example, in this work we perform a direct comparison of lattice QCD simulations with the QCD sum rule approach. The quark correlator is first investigated in the framework of QCD sum rules…
We calculate meson correlators in the epsilon-regime within partially quenched chiral perturbation theory. The valence quark masses and sea quark masses can be chosen arbitrary and all non-degenerate. Taking some of the sea quark masses to…
We analyze the relation between instantons and abelian projected monopoles in both phases of pure QCD by calculating local correlation functions between topological charge densities and monopole densities. On an $8^{3} \times 4$ lattice, it…
Instanton calculations in QCD are generically plagued by infrared divergencies associated with the integration over the instanton size $\rho$. Here, we demonstrate explicitly that the typical inverse hard momentum scale ${\mathcal Q}^{-1}$…
Axion models with generation-dependent Peccei-Quinn charges can lead to flavor-changing neutral currents, thus motivating QCD axion searches at precision flavor experiments. We rigorously derive limits on the most general effective…
We calculate the electromagnetic pion form factor at intermediate space-like momentum transfer from the QCD sum rule for the correlation function of two {\it pseudoscalar } interpolating fields and the electromagnetic current. This…
The Standard Model of particle physics predicts the existence of quantum tunnelling processes across topological inequivalent vacua, known as Instantons. In the electroweak sector, instantons provide a source of baryon asymmetry within the…
The non-diagonal correlators of vector and scalar currents are considered at three-loop order in QCD. The full mass dependence is computed in the case where one of the quarks is massless and the other one carries mass $M$. We exploit the…
We argue that lattice calculations of the $\eta'$ mass in QCD with $N_c=2$ colors performed at non-zero baryon chemical potential can be used to study the mechanism responsible for the mass of the $\eta'$. QCD with two colors is an ideal…
The known calculations of the fermion condensate $<\bar{\psi}\psi>$ and the correlator $<\bar{\psi}\psi(x) ~\bar{\psi}\psi(0)>$ have been interpreted in terms of {\em localized} instanton solutions minimizing the {\em effective} action.…
A straightforward algebraic derivation is carried out of light quark propagator and effective action in the instanton-anti-instanton molecule. Exact expressions are obtained which contain contributions of all quark modes. Possible…
In the lecture we review several issues related to recent development in non-perturbative QCD. The ``instanton liquid model'' reproduces not only the basic vacuum parameters (the condensates), but even hadronic correlators. New information…
In this paper the quark zero modes creation effect is studied in the context of the AdS/QCD approach. This effect is generated, in presence of instantons, by a new that can be added in the bulk.
Instanton-dyons are topological solitons -- solutions of Yang-Mills equations -- which appear at non-trivial expectation value of $A_0$ at nonzero temperatures. Using the ensembles of those, generated in our previous work, for 2-color and…
To elucidate the role played by instantons in chiral symmetry breaking, we explore their properties in full QCD, around the critical temperature. We study in particular spatial correlations between low-lying Dirac eigenmodes and instantons.…
We investigate chiral-restoration patterns of QCD for N_{c}=3 and N_{f}=2 at finite temperature (T) and zero quark-chemical potential beyond the chiral limit, indicating the explicit chiral-symmetry breaking. To this end, we employ the…
In QCD the spontaneous breaking of chiral symmetry and the U(1) axial anomaly can be understood considering instantons as the gauge configurations mediating quark-quark interaction. The existence of an exact zero mode solution of the Dirac…
We studied meson-meson interactions using the 't Hooft model, which represents QCD in 1+1 dimensions and assumes a large number of colors ($N_c$). The dominant interactions in this large $N_c$ limit are generated by quark exchange. Our…
The instanton size $\rho$ and inter-instanton distance $R$ are the main parameters of Instanton Liquid Model (ILM) of the QCD vacuum. Various estimates show that $\rho\approx1/3$ fm and $R\approx1$ fm, and the corresponding packing…
We measure correlations appropriate for favour-singlet mesons using dynamical quark configurations from UKQCD. Improved methods of evaluating the disconnected quark diagrams are presented. The scalar and pseudoscalar meson channels are…