The Experts below are selected from a list of 37803 Experts worldwide ranked by ideXlab platform
K V Stepanyantz  One of the best experts on this subject based on the ideXlab platform.

the all loop perturbative derivation of the nsvz beta β function and the nsvz scheme in the non Abelian Case by summing singular contributions
European Physical Journal C, 2020CoAuthors: K V StepanyantzAbstract:The perturbative allloop derivation of the NSVZ $$\beta $$ function for $${{\mathcal {N}}}=1$$ supersymmetric gauge theories regularized by higher covariant derivatives is finalized by calculating the sum of singularities produced by quantum superfields. These singularities originate from integrals of double total derivatives and determine all contributions to the $$\beta $$ function starting from the twoloop approximation. Their sum is expressed in terms of the anomalous dimensions of the quantum gauge superfield, of the Faddeev–Popov ghosts, and of the matter superfields. This allows obtaining the NSVZ equation in the form of a relation between the $$\beta $$ function and these anomalous dimensions for the renormalization group functions defined in terms of the bare couplings. It holds for an arbitrary renormalization prescription supplementing the higher covariant derivative regularization. For the renormalization group functions defined in terms of the renormalized couplings we prove that in all loops one of the NSVZ schemes is given by the HD + MSL prescription.

the all loop perturbative derivation of the nsvz beta function and the nsvz scheme in the non Abelian Case by summing singular contributions
arXiv: High Energy Physics  Theory, 2020CoAuthors: K V StepanyantzAbstract:The perturbative allloop derivation of the NSVZ $\beta$function for ${\cal N}=1$ supersymmetric gauge theories regularized by higher covariant derivatives is finalized by calculating the sum of singularities produced by quantum superfields. These singularities originate from integrals of double total derivatives and determine all contributions to the $\beta$function starting from the twoloop approximation. Their sum is expressed in terms of the anomalous dimensions of the quantum gauge superfield, of the FaddeevPopov ghosts, and of the matter superfields. This allows obtaining the NSVZ equation in the form of a relation between the $\beta$function and these anomalous dimensions for the renormalization group functions defined in terms of the bare couplings. It holds for an arbitrary renormalization prescription supplementing the higher covariant derivative regularization. For the renormalization group functions defined in terms of the renormalized couplings we prove that in all loops one of the NSVZ schemes is given by the HD+MSL prescription.

three loop nsvz relation for terms quartic in the yukawa couplings with the higher covariant derivative regularization
Nuclear Physics, 2017CoAuthors: Yu V Shakhmanov, K V StepanyantzAbstract:We demonstrate that in nonAbelian N=1 supersymmetric gauge theories the NSVZ relation is valid for terms quartic in the Yukawa couplings independently of the subtraction scheme if the renormalization group functions are defined in terms of the bare couplings and the theory is regularized by higher covariant derivatives. The terms quartic in the Yukawa couplings appear in the threeloop βfunction and in the twoloop anomalous dimension of the matter superfields. We have obtained that the threeloop contribution to the βfunction quartic in the Yukawa couplings is given by an integral of double total derivatives. Consequently, one of the loop integrals can be taken and the threeloop contribution to the βfunction is reduced to the twoloop contribution to the anomalous dimension. The remaining loop integrals have been calculated for the simplest form of the higher derivative regularizing term. Then we construct the renormalization group functions defined in terms of the renormalized couplings. In the considered approximation they do not satisfy the NSVZ relation for a general renormalization prescription. However, we verify that the recently proposed boundary conditions defining the NSVZ scheme in the nonAbelian Case really lead to the NSVZ relation between the terms of the considered structure.
Conrad Newton  One of the best experts on this subject based on the ideXlab platform.

generalized gauge transformation Abelian Case
Physics Letters B, 1994CoAuthors: R Gastmans, Conrad NewtonAbstract:Abstract A gauge transformation in quantum electrodynamics involves the product of field operators at the same spacetime point and hence does not have a welldefined meaning. One way to avoid this difficulty is to generalized the gauge transformation by using different spacetime points in the spirit of Dirac's point splitting. It is found that such a generalization indeed exists and the resulting generalized infinitesimal gauge transformation takes the form of an infinite series in the coupling constant.
Michele Simionato  One of the best experts on this subject based on the ideXlab platform.

gauge consistent wilson renormalization group i the Abelian Case
International Journal of Modern Physics A, 2000CoAuthors: Michele SimionatoAbstract:A version of the Exact Renormalization Group Equation consistent with gauge symmetry is presented. A discussion of its regularization and renormalization is given. The relation with the Callan–Symanzik equation is clarified.

gauge consistent wilson renormalization group i Abelian Case
arXiv: High Energy Physics  Theory, 1998CoAuthors: Michele SimionatoAbstract:A version of the Wilson Renormalization Group Equation consistent with gauge symmetry is presented. A perturbative renormalizability proof is established. A wilsonian derivation of the CallanSymanzik equation is given.
R Gastmans  One of the best experts on this subject based on the ideXlab platform.

generalized gauge transformation Abelian Case
Physics Letters B, 1994CoAuthors: R Gastmans, Conrad NewtonAbstract:Abstract A gauge transformation in quantum electrodynamics involves the product of field operators at the same spacetime point and hence does not have a welldefined meaning. One way to avoid this difficulty is to generalized the gauge transformation by using different spacetime points in the spirit of Dirac's point splitting. It is found that such a generalization indeed exists and the resulting generalized infinitesimal gauge transformation takes the form of an infinite series in the coupling constant.
Giovanni Garberoglio  One of the best experts on this subject based on the ideXlab platform.

heavy quark bound states in a quark gluon plasma dissociation and recombination
Nuclear Physics, 2016CoAuthors: Jeanpaul Blaizot, Davide De Boni, Pietro Faccioli, Giovanni GarberoglioAbstract:Abstract We present a comprehensive approach to the dynamics of heavy quarks in a quark–gluon plasma, including the possibility of bound state formation and dissociation. In this exploratory paper, we restrict ourselves to the Case of an Abelian plasma, but the extension of the techniques used to the nonAbelian Case is doable. A chain of well defined approximations leads eventually to a generalized Langevin equation, where the force and the noise terms are determined from a correlation function of the equilibrium plasma, and depend explicitly on the configuration of the heavy quarks. We solve the Langevin equation for various initial conditions, numbers of heavy quark–antiquark pairs and temperatures of the plasma. Results of simulations illustrate several expected phenomena: dissociation of bound states as a result of combined effects of screening of the potential and collisions with the plasma constituent, formation of bound pairs (recombination) that occurs when enough heavy quarks are present in the system.