Unravelling soft components in the shape function for inclusive B decays
  In the heavy-quark limit, the decay spectrum for radiative and semileptonic inclusive B-meson decays is determined by a universal structure function, i.e. the shape function. We study the constraints on the bilocal heavy-quark operator for the shape function from the QCD equations of motion and heavy-quark symmetry, and we obtain a new basis of nonlocal operators that reveals relevant soft components in the shape function. Those nonlocal operators represent the ``kinetic energy distribution'' of the b-quark inside the B-meson and the four-parton correlations with additional quarks and gluons. A corresponding local operator basis relevant for relating the shape function to HQET parameters is also given, and novel effects of the quark-gluon correlations are discussed. 
Hiroyuki Kawamura (1), Jiro Kodaira (2), Kazuhiro Tanaka (3) ((1) KEK,   (2) Hiroshima Univ., (3) Juntendo Univ.)