出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：We construct the S-wave part of the electromagnetic vector annihilation current to O(asv2), where
v is the non-relativistic quark velocity, for heavy quarks whose dynamics are described by the
NRQCD action on the lattice. The NRQCD vector current for Q ¯Q annihilation is expressed as a
linear combination of lattice operators with quantum numbers L=0, JP =1−, and the coefficients
are determined by matching to the corresponding continuum current in QCD to O(v2) at oneloop.
The annihilation channel gives a complex amplitude with Coulomb-exchange and infrared
singularities, making a careful choice for the contours of integration and infrared subtraction
functions in the numerical integration necessary. An automated vertex generation program written
in Python is employed, allowing us to use a realistic NRQCD action and an improved gluon lattice
action; a change in the definition of either action is easily accommodated in this procedure. The
final result is applicable to simulations of electromagnetic decays of heavy quarkonia, notably the
¡ meson.
