On the chirally rotated Schrödinger functional with Wilson fermions
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Department
Mathematisch-Naturwissenschaftliche Fakultät I
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Abstract
Viele Phaenomene in der Natur sind eng verknuepft mit dem Niederenergieverhalten der QCD und damit von nicht-perturbative Natur. Viele Groeßen benoetigen auch eine nicht-perturbative Renormierung. Als nicht-perturbative Renormierungsschema schlagen wir das chiral gedrehte Schroedingerfunktional, χSF, in einer Gitterregularisierung vor. Auf dem Baumgraphenniveau wird eine analytische Rechnung im Kontinuum und auf dem Gitter durchgefuehrt. Weitere Untersuchungen werden dann in der Valenzquark-Approximation der Gitter QCD durchgefuehrt. Eines der Hauptziele ist es dabei, die im χSF benoetigten Koeffizienten nicht-perturbativ so einzustellen, dass ein wohl-definierter Kontinuumlimes durchgefuehrt werden kann. Es wird gezeigt, dass solch eine Feineinstellung der Parameter des χSF durchfuehrbar ist und dass physikalische Groeßen nicht sensitiv auf die spezielle Wahl der Bedingung zur Einstellung der Parameter sind. Es wird gezeigt, dass das Skalierungsverhalten physikalischer Groeßen konsistent mit fuehrenden O(a2) Diskretisierungseffekten ist. Das Hauptergebnis dieser Arbeit ist der Nachweis, dass das χSF mit den hier berechneten Verbesserungskoeffizienten, zu einem korrekten Kontinuumlimes fuehrt. Dazu wurden drei unterschiedliche Werte der Renormierungsskala verwendet und mehrere uns interessierende physikalische Groeßen berechnet. Wir koennen deshalb den Schluss ziehen, dass das χSF ein viel versprechendes Renormierungsschema darstellt, um eine nicht-perturbative Renormierung vorzunehmen und dabei gleichzeitig die automatische O(a)-Verbesserung aufrecht erhalten. Dies eroeffnet den sehr wichtigen Ausblick, dass das χSF in zukuenftigen nicht-perturbativen Berechnungen von Renormierungskonstanten auch ueber die Valenzquark-Approximation hinaus eingesetzt werden kann.
There are many phenomena in nature which are closely linked to the low energy regime of QCD. Theoretically, these can be dealt with only by means of non-perturbative methods. Often, a non-perturbative renormalization of QCD is required. We employ a 4-dimensional lattice as a regulator of QCD. As a non-perturbative renormalization scheme, we propose the chirally rotated Schrödinger functional, χSF. We perform analytical studies at tree-level of perturbation theory, in the continuum and on the lattice. Beyond tree-level, all studies are performed in the quenched approximation of QCD. One of the main targets has been to perform the non-perturbative tuning of the two required coefficients of the χSF scheme, such that a well defined continuum limit can be reached. We demonstrate that the tuning is feasible and physical quantities are insensitive to the tuning condition. There are also a couple of improvement counterterms at the boundaries. However, besides these boundary O(a) effects, the χSF is expected to be compatible with bulk automatic O(a)-improvement. We show that the scaling behavior of physical quantities is consistent with automatic O(a)-improvement. The other most important achievement has been to demonstrate that the χSF, with the here computed tuning coefficients, leads to the correct continuum limit. For this, we have performed universality tests of the continuum limit, at three different values of the renormalization scale and through the computation of several physical quantities of interest. The conclusion of these results is that the χSF is a promising scheme to perform non-perturbative renormalizations while maintaining bulk automatic O(a)-improvement. This opens the most relevant prospect that the χSF can be safely used in future non-perturbative computations of renormalization factors also beyond the quenched approximation.
There are many phenomena in nature which are closely linked to the low energy regime of QCD. Theoretically, these can be dealt with only by means of non-perturbative methods. Often, a non-perturbative renormalization of QCD is required. We employ a 4-dimensional lattice as a regulator of QCD. As a non-perturbative renormalization scheme, we propose the chirally rotated Schrödinger functional, χSF. We perform analytical studies at tree-level of perturbation theory, in the continuum and on the lattice. Beyond tree-level, all studies are performed in the quenched approximation of QCD. One of the main targets has been to perform the non-perturbative tuning of the two required coefficients of the χSF scheme, such that a well defined continuum limit can be reached. We demonstrate that the tuning is feasible and physical quantities are insensitive to the tuning condition. There are also a couple of improvement counterterms at the boundaries. However, besides these boundary O(a) effects, the χSF is expected to be compatible with bulk automatic O(a)-improvement. We show that the scaling behavior of physical quantities is consistent with automatic O(a)-improvement. The other most important achievement has been to demonstrate that the χSF, with the here computed tuning coefficients, leads to the correct continuum limit. For this, we have performed universality tests of the continuum limit, at three different values of the renormalization scale and through the computation of several physical quantities of interest. The conclusion of these results is that the χSF is a promising scheme to perform non-perturbative renormalizations while maintaining bulk automatic O(a)-improvement. This opens the most relevant prospect that the χSF can be safely used in future non-perturbative computations of renormalization factors also beyond the quenched approximation.
Description
Keywords
Gitter QCD, Renormierung, Verbesserung, Chirale Symmetrie, Lattice QCD, chiral symmetry, renormalization, improvement
Dewey Decimal Classification
530 Physik
Citation
López, Jénifer González.(2011). On the chirally rotated Schrödinger functional with Wilson fermions. 10.18452/16346