Pregled međuigre slabih i hadronskih skyrmiona

We review a case of cross-fertilization of two distinct areas of physics, namely, hadronic and electroweak theory. In hadronic physics, concepts like solitons, nonperturbative and nonlinear phenomena, and anomalies have found many applications in the Skyrme model of baryons. This has in turn given a large additional impetus to the studies of such concepts and phenomena in electroweak physics too. To close the circle, these studies give us clues how to represent the other kind of hadrons, namely mesons, as solitons of the Skyrme type.Dan je pregled jednog slučaja unakrsne fertilizacije dvaju različitih područja fizike, naime hadronske i elektroslabe teorije. U hadronskoj fizici, pojmovi kao solitoni, neperturbativne i nelinearne pojave i anomalije mnogo su primjenjivani u Skyrmeovom model u bariona. To je pak dalo veliki dodatni podsticaj proučavanjima takvih pojmova i pojava u fizici elektroslabih procesa. Krug se zatvara time što nam ta proučavanja kažu kako prikazati drugu vrstu hadrona, naime mezone, kao solitone Skyrmeovog tipa

Pseudoscalar qqbar mesons and effective QCD coupling enhanced by <A^2> condensate

Recent developments provided evidence that the dimension 2 gluon condensate is important for the nonperturbative regime of Yang-Mills theories (quantized in the Landau gauge). We show that it may be relevant for the Dyson-Schwinger approach to QCD. In order that this approach leads to a successful hadronic phenomenology, an enhancement of the effective quark-gluon interaction seems to be needed at intermediate (p^2 \sim 0.5 GeV^2) momenta. It is shown that the gluon condensate provides such an enhancement. It is also shown that the resulting effective strong running coupling leads to the sufficiently strong dynamical chiral symmetry breaking and successful phenomenology at least in the light sector of pseudoscalar mesons.Comment: revtex4, 4 eps figures, 8 pages, improved presentation, to appear in Phys. Rev.

Pregled međuigre slabih i hadronskih skyrmiona

We review a case of cross-fertilization of two distinct areas of physics, namely, hadronic and electroweak theory. In hadronic physics, concepts like solitons, nonperturbative and nonlinear phenomena, and anomalies have found many applications in the Skyrme model of baryons. This has in turn given a large additional impetus to the studies of such concepts and phenomena in electroweak physics too. To close the circle, these studies give us clues how to represent the other kind of hadrons, namely mesons, as solitons of the Skyrme type.Dan je pregled jednog slučaja unakrsne fertilizacije dvaju različitih područja fizike, naime hadronske i elektroslabe teorije. U hadronskoj fizici, pojmovi kao solitoni, neperturbativne i nelinearne pojave i anomalije mnogo su primjenjivani u Skyrmeovom model u bariona. To je pak dalo veliki dodatni podsticaj proučavanjima takvih pojmova i pojava u fizici elektroslabih procesa. Krug se zatvara time što nam ta proučavanja kažu kako prikazati drugu vrstu hadrona, naime mezone, kao solitone Skyrmeovog tipa

Bethe–Salpeterova jednadžba s efektivnim QCD vezanjem i 〈A2〉-pojačanjem

Dyson-Schwinger equations provide an effective approach to physics of strong interactions. To reproduce the hadronic phenomenology well, the Dyson-Schwinger approach in the rainbow-ladder approximation must employ an effective interaction between quarks which is fairly strong at intermediate (Q2 ∼ 0.5 GeV2 ) spacelike transferred momenta. We have recently proposed that such an interaction may originate from the dimension-2 gluon condensate 〈A2〉 which has recently attracted much attention. We showed that the resulting effective running coupling leads to the sufficiently strong dynamical chiral symmetry breaking and successful phenomenology, at least in the light sector of pseudoscalar mesons. In the present paper, we give a more detailed investigation of the parameter dependence of these results.Dyson-Schwingerove jednadžbe predstavljaju važan pristup fizici jakih međudjelovanja. Da bi se dobro opisala hadronska fenomenologija, Dyson-Schwingerov pristup u ljestvičastom približenju mora rabiti efektivno međudjelovanje među kvarkovima koje je prilično jako na srednjim (Q2 ∼ 0.5 GeV2 ) prostornim prijenosima impulsa. Nedavno smo predložili da to međudjelovanje može nastati od gluonskog kondenzata 〈A2〉 i dimenzije 2, koji je u posljednje vrijeme privukao dosta pažnje. Pokazali smo da dobiveno efektivno vezanje vodi na dovoljno jako lomljenje dinamičke kiralne simetrije i uspješnu fenomenologiju, barem u sektoru lakih pseudoskalarnih mezona. U ovom radu opisujemo detaljno istraživanje parametarskih ovisnosti

The dependence of the asymptotic behaviour of the γ* γ → π^0 transition on the dressed quark-photon vertices

It is discussed how various Ansätze for the dressed quark-photon (qqγ) vertices Γ^µ(q,q´) influence the asymptotics of the γ* γ→ π^0 transition form factor. In this regard, we rectify certain misconceptions present in the literature

Ovisnost asimptotskog ponašanja prijelaza γ* γ u π0 o obučenim vrhovima kvark-foton

It is discussed how various Ansätze for the dressed quark-photon (qqγ) vertices Γµ(q,q˘) influence the asymptotics of the γ*γ → π0 transition form factor. In this regard, we rectify certain misconceptions present in the literature.Raspravljamo kako razne postavke za obučene vrhove kvark-foton (qqγ) Γµ(q, q0 ) utječu na asimptotsko ponašanje formfaktora prijelaza γ*γ → π0. Ispravljamo neka pogrešna shvaćanja koja se nalaze u literaturi

Bethe–Salpeterova jednadžba s efektivnim QCD vezanjem i 〈A2〉-pojačanjem

Dyson-Schwinger equations provide an effective approach to physics of strong interactions. To reproduce the hadronic phenomenology well, the Dyson-Schwinger approach in the rainbow-ladder approximation must employ an effective interaction between quarks which is fairly strong at intermediate (Q2 ∼ 0.5 GeV2 ) spacelike transferred momenta. We have recently proposed that such an interaction may originate from the dimension-2 gluon condensate 〈A2〉 which has recently attracted much attention. We showed that the resulting effective running coupling leads to the sufficiently strong dynamical chiral symmetry breaking and successful phenomenology, at least in the light sector of pseudoscalar mesons. In the present paper, we give a more detailed investigation of the parameter dependence of these results.Dyson-Schwingerove jednadžbe predstavljaju važan pristup fizici jakih međudjelovanja. Da bi se dobro opisala hadronska fenomenologija, Dyson-Schwingerov pristup u ljestvičastom približenju mora rabiti efektivno međudjelovanje među kvarkovima koje je prilično jako na srednjim (Q2 ∼ 0.5 GeV2 ) prostornim prijenosima impulsa. Nedavno smo predložili da to međudjelovanje može nastati od gluonskog kondenzata 〈A2〉 i dimenzije 2, koji je u posljednje vrijeme privukao dosta pažnje. Pokazali smo da dobiveno efektivno vezanje vodi na dovoljno jako lomljenje dinamičke kiralne simetrije i uspješnu fenomenologiju, barem u sektoru lakih pseudoskalarnih mezona. U ovom radu opisujemo detaljno istraživanje parametarskih ovisnosti