arXiv subjects

D. V. Shirkov

Publications and source records attributed to D. V. Shirkov.

40 records · Page 3Linked to original sources

arXiv1996

Continuous mass-dependent analysis of the non--singlet DIS data

We consider the issue of an accurate description of the evolution of the non-singlet structure function moments $M_n(Q)$ near heavy quark threshold. To this aim we propose a simple modification of the standard massless \MSbar scheme approach to the next-to-leading QCD analysis of DIS data. We apply it to the processing of the modern CCFR data for $xF_3$ structure function and extract the value of $α_s(M_z) \approx 0.108 \pm 0.004$ We check also the consistency of light gluino hypothesis with CCFR data.

hep-ph↗

arXiv1996

Analytic QCD running coupling with finite IR behaviour and universal ${\bar α}_s(0)$ value

As is known from QED, a possible solution to the ghost-pole trouble can be obtained by imposing the $Q^2$-analyticity imperative. Here, the pole is compensated by the $α$ non-analytic contribution that results in finite coupling renormalization. We apply this idea to QCD and arrive at the $Q^2$ analytic $\barα_s(Q)$. This solution corresponds to perturbation expansion, obeys AF and, due to non-perturbative contribution, has a regular IR behaviour. It does not contain any adjustable parameter and has a finite IR limit $\barα_s(0)$ which depends only on group symmetry factors. In the one-loop approximation it is equal to $4π/β_0 \simeq 1.40\,$ and turns out to be surprisingly stable with respect to higher order corrections. On the other hand, the IR behaviour of our new analytic solution agrees with recent global low energy experimental estimates of $\barα_s(Q^2)$.

hep-ph↗

arXiv1996

The Bogoliubov Renormalization Group

We begin with personal notes describing the atmosphere of "Bogoliubov renormalization group" birth. Then we expose the history of RG discovery in the QFT and of the RG method devising in the mid-fifties. The third part is devoted to proliferation of RG ideas into diverse parts of theoretical physics. We conclude with discussing the perspective of RG method further development and its application in mathematical physics.

hep-th↗

arXiv1994

Mass Dependent $α_S$ Evolution and the Light Gluino Existence

There is an intriguing discrepancy between α_s(M_Z) values measured directly at the CERN $Z_0$-factory and low-energy (at few GeV) measurements transformed to $Q=M_{Z_0}$ by a massless QCD α_s(Q) evolution relation. There exists an attempt to reconcile this discrepancy by introducing a light gluino $\gl$ in the MSSM. We study in detail the influence of heavy thresholds on α_s(Q) evolution. First, we consruct the "exact" explicit solution to the mass-dependent two-loop RG equation for the running α_s(Q). This solution describes heavy thresholds smoothly. Second, we use this solution to recalculate anew α_s(M_Z) values corresponding to "low-energy" input data. Our analysis demonstrates that using {\it mass-dependent RG procedure} generally produces corrections of two types: Asymptotic correction due to effective shift of threshold position; Local threshold correction only for the case when input experiment lies in the close vicinity of heavy particle threshold: $Q_{expt} \simeq M_h $. Both effects result in the effective shift of the \asmz values of the order of $10^{-3}$. However, the second one could be enhanced when the gluino mass is close to a heavy quark mass. For such a case the sum effect could be important for the discussion of the light gluino existence as it further changes the $\gl$ mass.

hep-ph↗