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A. G. Grozin

Publications and source records attributed to A. G. Grozin.

At least 37 records · Page 2Linked to original sources
arXiv2007

The B-meson mass splitting from non-perturbative quenched lattice QCD

We perform the non-perturbative (quenched) renormalization of the chromo-magnetic operator in Heavy Quark Effective Theory and its three-loop matching to QCD. At order 1/m of the expansion, the operator is responsible for the mass splitting between the pseudoscalar and vector B-mesons. These new computed factors are affected by an uncertainty negligible in comparison to the known bare matrix element of the operator between B-states. Furthermore, they push the quenched determination of the spin splitting for the Bs-meson much closer to its experimental value than the previous perturbatively renormalized computations. The renormalization factor for three commonly used heavy quark actions and the Wilson gauge action and useful parametrizations of the matching coefficient are provided.

hep-lat↗
arXiv2007

Three-Loop Chromomagnetic Interaction in HQET

We compute the three-loop QCD corrections to the quark chromomagnetic moment and thus obtain the matching coefficient and the anomalous dimension of the chromomagnetic interaction in HQET. As a byproduct we obtain the three-loop corrections to the quark anomalous magnetic moment.

hep-ph↗
arXiv2007

Decoupling of heavy quarks in HQET

Decoupling of c-quark loops in b-quark HQET is considered. The decoupling coefficients for the HQET heavy-quark field and the heavy-light quark current are calculated with the three-loop accuracy. The last result can be used to improve the accuracy of extracting f_B from HQET lattice simulations (without c-quark loops). The decoupling coefficient for the flavour-nonsinglet QCD current with n antisymmetrized gamma-matrices is also obtained at three loops; the result for the tensor current (n=2) is new.

hep-ph↗
arXiv2005

B-meson distribution amplitudes

B-meson light-cone distribution amplitudes are discussed in these lectures in the framework of HQET. The evolution equation for the leading-twist distribution amplitude is derived in one-loop approximation. QCD sum rules for distribution amplitudes are discussed.

hep-ph↗
arXiv2005

TeXmacs-maxima interface

This tutorial presents features of the new and improved TeXmacs-maxima interface. It is designed for running maxima-5.9.2 from TeXmacs-1.0.5 (or later).

cs.SC↗
arXiv2004

Correlator of heavy-quark currents at small q^2 in the large-beta_0 limit

The correlator of vector heavy-quark currents at small q^2 is considered in the large-beta_0 limit. The leading IR renormalon ambiguity of the sum of the perturbative series is canceled by the UV renormalon ambiguity of the gluon condensate. Asymptotic behaviour of the perturbative series is obtained in a model-independent way, up to a single unknown normalization factor. Gluon-virtuality distribution functions for the perturbative correction are calculated.

hep-ph↗
arXiv2003

Lectures on multiloop calculations

I discuss methods of calculation of propagator diagrams (massless, those of Heavy Quark Effective Theory, and massive on-shell diagrams) up to 3 loops. Integration-by-parts recurrence relations are used to reduce them to linear combinations of basis integrals. Non-trivial basis integrals have to be calculated by some other method, e.g., using Gegenbauer polynomial technique. Many of them are expressed via hypergeometric functions; in the massless and HQET cases, their indices tend to integers at $ε\to0$. I discuss the algorithm of their expansion in $ε$, in terms of multiple $ζ$ values. These lectures were given at Calc-03 school, Dubna, 14--20 June 2003.

hep-ph↗
arXiv2003

Renormalons: technical introduction

The large-beta_0 limit of QCD is discussed, with the emphasize on simple technical methods of calculating various quantities at the order 1/β_0. Many examples, mainly from heavy quark physics, are considered. Some QCD results based on renormalization group (and not restricted to the large-β_0 limit) are also discussed.

hep-ph↗
arXiv2003

Asymptotics of the perturbative series for f_{B^*}/f_B

We investigate the structure of the leading IR renormalon singularity in the QCD/HQET matching coefficients for heavy-light quark currents beyond the large-β_0 limit. From this result, we derive the large-order behaviour of the perturbative series for these coefficients, and for ratios of meson matrix elements, such as f_{B^*}/f_B.

hep-ph↗
arXiv2003

Perturbative HQET

Methods of calculation of loop diagrams in Heavy Quark Effective Theory (HQET) are presented.

hep-ph↗
arXiv2002

Some topics in heavy-quark physics

Some topics which can be easily explained to undergraduate students are presented, with elementary derivations. For a more systematic treatment of heavy-quark physics, see the textbook by Manohar and Wise.

hep-ph↗
arXiv2002

Multiloop calculations in HQET

Recently, algorithms for calculation of 3-loop propagator diagrams in HQET and on-shell QCD with a heavy quark have been constructed and implemented. These algorithms (based on integration by parts recurrence relations) reduce an arbitrary diagram to a combination of a finite number of basis integrals. Here I discuss various ways to calculate non-trivial bases integrals, either exactly or as expansions in epsilon. Some integrals of these two classes are related to each other by inversion, which provides a useful cross-check.

hep-ph↗
arXiv2001

TeXmacs interfaces to Maxima, MuPAD and REDUCE

GNU TeXmacs is a free wysiwyg word processor providing an excellent typesetting quality of texts and formulae. It can also be used as an interface to Computer Algebra Systems (CASs). In the present work, interfaces to three general-purpose CASs have been implemented.

cs.SC↗