Theoretical predictions for Bhabha scattering at the two-loop level require the inclusion of hadronic vacuum polarization in the photon propagator. We present predictions for the contributions from reducible amplitudes which are proportional to the vacuum polarization π(q) and from irreducible ones where the vacum polarization appears in a loop representing vertex or box diagramms. The second c...

The Cornell potential with the best fitted parameters αs and κ are modified by adding terms derived from non-perturbative QCD, which are characterized by a series of non-vanishing vacuum condensates of quarks and gluons. In terms of this potential, we study the system of heavy quarkonia. The results show that the correction caused by the additional terms reduces the deviation between the data a...

We discuss the coupling of heavy moduli fields to light fields when the dynamics of the latter, absent such couplings, yields metastable vacua. We show that the survival of the vacuum structure of the local model depends nontrivially on the cross-couplings of the two sectors. In particular we find that for ”local” models (such as those realized by D-branes in type II string theories) with metas...

A test for the Gaussian and exponential Ansätze for the nonperturbative parts of the coefficient functions, D and D 1 , which parametrize the gauge-invariant bilocal correlator of the field strength tensors in the stochastic vacuum model of QCD, is proposed. It is based on the evaluation of the heavy-quark condensate within this model by making use of the world-line formalism and equating the o...

One of the fundamental questions in strong interaction physics concerns the generation of mass in the sector of light quarks. How can nucleons with a mass of roughly 1 GeV arise from up and down quark masses of less than 10 MeV? The answer lies in the nonperturbative structure of the QCD vacuum itself in which quarks and gluons condense. This is in marked contrast to the heavy-quark sector wher...

The quark-line disconnected diagram is a potentially important ingredient in lattice QCD calculations of the hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon. It is also a notoriously difficult one to evaluate. Here, for the first time, we give an estimate of this contribution based on lattice QCD results that have a statistically significant signal, albeit...

Effective operators and vacuum instability as heralds of new physics Abstract For a light enough Higgs boson, the effective potential of the Standard Model develops a dangerous instability at some high energy scale, Λ, signalling the need for new physics below that scale. On the other hand, a typical low-energy remnant of new physics at some heavy scale, M , is the presence of effective non-ren...

It is pointed out that the hadron spectroscopy should be a study of the structure of the QCD vacuum, low-energy elementary excitations on top of which are hadrons. Concentrating on the dynamical breaking of the chiral symmetry in the QCD vacuum, we emphasize the importance to clarify what is going on with mesons in the I = J = 0-channel, i.e., the sigma meson channel, because it is connected to...

We show that adding a vacuum expectation value to a gauge field left over from a dimensional reduction of three-dimensional pure supersymmetric YangMills theory generates mass terms for the fundamental fields in the two-dimensional theory while supersymmetry stays intact. This is similar to the adjoint mass term that is generated by a Chern-Simons term in this theory. We study the spectrum of t...