We clarify some aspects of the LSZ formalism and wave function renormalisation for unstable particles in the presence of electroweak interactions when mixing and CP violation are considered. We also analyse the renormalisation of the CKM mixing matrix which is closely related to wave function renormalisation. We critically review earlier attempts to define a set of “on-shell” wave function reno...

The goal of this paper is to present a local convergence analysis of Newton’s method for approximating a locally unique solution of an equation in a Banach space setting. Using the gauge function theory and our new idea of restricted convergence regions we present an extended and unified convergence theory. Key–Words: Newton’s method, Banach space, semilocal convergence, gauge function, converg...

We study operators to create hadronic states made of light quarks in quenched lattice gauge theory. We construct non-local gauge-invariant operators which provide information about the spatial extent of the ground state and excited states. The efficiency of the operators is shown by looking at the wave function of the first excited state, which has a node as a function of the spatial extent of ...

The semiclassical approximation for the partition function in Chern–Simons gauge theory is derived using the invariant integration method. Volume and scale factors which were undetermined and had to be fixed by hand in previous derivations are automatically taken account of in this framework. Agreement with Witten’s exact expressions for the partition function in the weak coupling (large k) lim...

The goal of this seminar is to understand the Nekrasov partition function introduced by Nekrasov in 2003 [Nek03]. This is a generating function for correlation functions in an N = 2 supersymmetric gauge theory, so my goal today is to explain what N = 2 gauge theory is and why we might find it interesting. We begin with the latter question, why is this interesting? There are two intertwined answ...

The gauge invariant two-point correlation function of the gauge field strength tensor is calculated in perturbation theory at the next-to-leading order. Besides a direct calculation in perturbative QCD we also present a derivation of the correlation function in the heavy quark effective theory. Our results are briefly compared with recent determinations of the field strength correlator on the l...

We quantize non-commutative Maxwell theory canonically in the background field gauge for weak and slowly varying background fields. We determine the complete basis for expansion under such an approximation. As an application, we derive the Wigner function which determines the leading order high temperature behavior of the perturbative amplitudes of non-commutative Maxwell theory. To leading ord...

We non-perturbatively study the fermion spectrum in the chiral symmetric phase focusing on the effects of in-medium corrections for gauge boson. The fermion spectrum is derived by solving the Schwinger-Dyson equation (SDE) with ladder approximation on the real time axis. It is shown that the peak of the fermion spectral function is broadened by in-medium effects for gauge boson compared with th...

This paper describes and proves a canonical procedure to decouple perturbations and optimize their gauge around backgrounds with one non-homogeneous dimension, namely of co-homogeneity 1, while preserving locality in this dimension. Derivativelygauged fields are shown to have a purely algebraic action; they can be decoupled from the other fields through gauge-invariant re-definitions; a potenti...

Using the higher covariant derivatives and gauge invariant Pauli-Villars regularization of gauge theories in the framework of the background field method, we obtain a version of the exact renormalization group equation for the regulator fields, whose vacuum energy depends on the background gauge field. It is evaluated using an anomalous Ward-Takahashi identity, which is related to the rescaling...