Alexander Efremov

• PhD
• PostDoc Position at University of Lille

We study nonlinear sigma models on target manifolds with constant (positive or negative) curvature using the functional renormalization group and the background field method. We pay particular attention to the splitting Ward identities associated to the invariance under reparametrization of the background field. Implementing these Ward identities i...

We study non-linear sigma models on target manifolds with constant (positive or negative) curvature using the functional renormalization group and the background field method. We pay particular attention to the splitting Ward identities associated to the invariance under reparametrization of the background field. Implementing these Ward identities...

We formulate the Hartree–Fock method using a functional integral approach. Then we consider a nonperturbative component of the vacuum polarization. For the Dirac–Coulomb operator the renormalization flow of the vacuum polarization is calculated numerically. For the Hartree–Fock operator the polarization is obtained by integrating an appropriately r...

We consider a general solution of the Langevin equation describing massive fermions to an appropriate boundary problem. Assuming existance we show that all correlators coincide with the Schwinger functions of corresponding Euclidean Quantum Field Theory.

We make progress towards a derivation of a low energy effective theory for SU(2) Yang–Mills theory. This low energy action is computed to 1-loop using the renormalization group technique, taking proper care of the Slavnov–Taylor identities in the Maximal Abelian Gauge. After that, we perform the Spin-Charge decomposition in a way proposed by Faddee...

The goal of this work is a rigorous perturbative construction of the SU(2) Yang-Mills theory in four dimensional Euclidean space. The functional integration technique gives a mathematical basis for establishing the differential Flow Equations of the renormalization group for the effective action. While the introduction of momentum space regulators...

We give a proof of perturbative renormalizability of SU(2) Yang--Mills theory in four-dimensional Euclidean space which is based on the Flow Equations of the renormalization group. The main motivation is to present a proof which does not make appear mathematically undefined objects (as for example dimensionally regularized generating functionals),...