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Titolo:
Gauge dependence and matching procedure of a nonrelativistic QED-QCD boundstate formalism - art. no. 105001
Autore:
Hasebe, K; Sumino, Y;
Indirizzi:
Tohoku Univ, Dept Phys, Sendai, Miyagi 9808578, Japan Tohoku Univ Sendai Miyagi Japan 9808578 ys, Sendai, Miyagi 9808578, Japan
Titolo Testata:
PHYSICAL REVIEW D
fascicolo: 10, volume: 6110, anno: 2000,
pagine: 5001 -
SICI:
0556-2821(20000515)6110:10<5001:GDAMPO>2.0.ZU;2-0
Fonte:
ISI
Lingua:
ENG
Soggetto:
QUARK PAIR PRODUCTION; MUONIUM HYPERFINE-STRUCTURE; PRODUCTION NEAR-THRESHOLD; EFFECTIVE-FIELD THEORIES; TO-LEADING ORDER; T(T)OVER-BAR PRODUCTION; MOMENTUM DISTRIBUTIONS; RADIATIVE-CORRECTIONS; LATTICE NRQCD; HEAVY QUARKS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
--discip_EC--
Citazioni:
65
Recensione:
Indirizzi per estratti:
Indirizzo: Hasebe, K Tohoku Univ, Dept Phys, Sendai, Miyagi 9808578, Japan Tohoku Univ Sendai Miyagi Japan 9808578 , Miyagi 9808578, Japan
Citazione:
K. Hasebe e Y. Sumino, "Gauge dependence and matching procedure of a nonrelativistic QED-QCD boundstate formalism - art. no. 105001", PHYS REV D, 6110(10), 2000, pp. 5001

Abstract

A nonrelativistic bound state formalism used in contemporary calculations is investigated. It is known that the effective Hamiltonian of the bound state system depends on the choice of gauge. We obtain the transformation charge Q of the Hamiltonian for an arbitrary infinitesimal change of gauge, bywhich gauge independence of the mass spectrum and gauge dependences of thebound state wave functions are dictated. We give formal arguments based onthe BRST symmetry supplemented by power countings of Coulomb singularitiesof diagrams. For illustration, (1) we calculate Q up to O(1/c) and (2) we examine the gauge dependences of diagrams for a decay of a q (q) over bar bound state up to O(1/c) and show that cumbersome gauge cancellations can becircumvented by directly calculating Q. As an application we point out that the present calculations of the top quark momentum distribution in the t (t) over bar threshold region are gauge dependent. We also show the possibilities for incorrect calculations of physical quantities of bound states when the on-shell matching procedure is employed. We give a proof of a justification for the use of the equation of motion to simplify the form of a local NRQCD Lagrangian. The formalism developed in this work will provide useful cross-checks in computations involving NRQED or NRQCD bound states.

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Documento generato il 05/12/20 alle ore 19:25:28