QCD-Instantons and Conformal Space-Time Inversion Symmetry

Autor(en)

Daniela Klammer, Fridger Schrempp

Abstrakt

In this paper, we explore the appealing possibility that the strong suppression of large-size QCD instantons — as evident from lattice data — is due to a surviving conformal space-time inversion symmetry. This symmetry is both suggested from the striking invariance of high-quality lattice data for the instanton size distribution under inversion of the instanton size ρ → langleρrangle2/ρ and from the known validity of space-time inversion symmetry in the classical instanton sector. We project the instanton calculus onto the four-dimensional surface of a five-dimensional sphere via conformal stereographic mapping, before investigating conformal inversion. This projection to a compact, curved geometry is both to avoid the occurence of divergences and to introduce the average instanton size ρ→langleρrangle2/ρ from the lattice data as a new length scale. The average instanton size is identified with the radius b of this 5d-sphere and acts as the conformal inversion radius. For b = langleρrangle, our corresponding results are almost perfectly symmetric under space-time inversion and in good qualitative agreement with the lattice data. For ρ/b → 0 we recover the familiar results of instanton perturbation theory in flat 4d-space. Moreover, we illustrate that a (weakly broken) conformal inversion symmetry would have significant consequences for QCD beyond instantons. As a further successful test for inversion symmetry, we present striking implications for another instanton dominated lattice observable, the chirality-flip ratio in the QCD vacuum.

Organisation(en)

Mathematische Physik

Externe Organisation(en)

Deutsches Elektronen-Synchrotron DESY

Journal

Journal of High Energy Physics

Band

2008

Anzahl der Seiten

24

ISSN

1029-8479

DOI

https://doi.org/10.1088/1126-6708/2008/06/098

Publikationsdatum

2008

Peer-reviewed

Ja

ÖFOS 2012

103008 Experimentalphysik

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/b36f16f3-0d35-4629-bcd6-dcc5a79fa22d