Renormalization in Minkowski space–time

The multiplicative and the functional renormalization group methods are applied for the four-dimensional scalar theory in Minkowski space–time. It is argued that the appropriate choice of the subtraction point is more important in Minkowski than in Euclidean space–time. The parameters of the cutoff theory, defined by a subtraction point in the quasi-particle domain, are complex due to the mass-shell contributions and the renormalization group flow becomes much more involved than its Euclidean counterpart.

Quark matter in the perturbation QCD model with a rapidly convergent matching-invariant running coupling

The properties of dense quark matter are investigated in the perturbation theory with a rapidly convergent matching-invariant running coupling. The fast convergence is mainly due to the resummation of an infinite number of known logarithmic terms in a compact form. The only parameter in this model, the ratio of the renormalization subtraction point to the chemical potential, is restricted to be about 2.64 according to the Witten–Bodmer conjecture, which gives the maximum mass and the biggest radius of quark stars to be, respectively, two times the solar mass and 11.7[Formula: see text]km.

Renormalization of Chiral Nuclear Forces with Multiple Subtractions in Peripheral Channels

We analyse the renormalization of the of two-nucleon interaction with multiple subtractions in peripheral waves considering two chiral forces at N3LO. Phase shifts at low energies are then computed with several subtraction points below μ=10 fm−1. We show that for most peripheral waves the phase shifts have nearly no dependence on the renormalization scale. In two cases the phase shifts converge slowly as the renormalization scale approaches μ=1 fm−1 and in one case the phase shifts presented oscillations with respect to the subtraction point μ.

Improved fD(s)∗, fB(s)∗ and fBc from QCD Laplace sum rules

Anticipating future precise measurements of the D- and B-like (semi)leptonic and hadronic decays for alternative determinations of the CKM mixing angles, we pursue our program on the D- and B-like mesons by improving the estimates of [Formula: see text] and [Formula: see text] (analogue to [Formula: see text]) by using the well-established (inverse) Laplace sum rules (LSR) and/or their suitable ratios less affected by the systematics, which are known to N2LO pQCD and where the complete [Formula: see text] nonperturbative condensate contributions are included. The convergence of the PT series is analyzed by an estimate of the N3LO terms based on geometric growth of the coefficients. In addition to the standard LSR variable [Formula: see text] and the QCD continuum threshold [Formula: see text] stability criteria, we extract our optimal results by also requiring stability on the variation of the arbitrary QCD subtraction point [Formula: see text] which reduces the errors in the analysis. We complete the study of the open bottom states by an estimate of [Formula: see text]. Our results summarized in Tables 3 and 4 are compared with some other recent sum rules and lattice estimates.

EFFECTIVE COUPLING CONSTANTS IN GAUGE THEORIES AT HIGH TEMPERATURE

High temperature behavior of the effective gauge coupling constants, defined through the effective Lagrangians L(H, T) of strong magnetic field H=const, is investigated for a number of models. In spinor QED the well-known zero charge behavior is realized in the limit T≫(gH)1/2>μ, μ is subtraction point in the field. In scalar QED in addition to logarithmic term ~ln T/T0 describing the zero charge, the term ~T/(gH)1/2 appears and dominates at high temperatures. Similar terms are also present in the non-Abelian models and spoil asymptotic freedom of perturbative vacuum. In the latter models, the linear in T terms are resulted in the generation of classical homogeneous magnetic fields. At this background asymptotic freedom is restored.