Testing factorization inB→D(*)Xdecays

Abstract

In QCD the amplitude forB 0 → D ( * )+ π − factorizes in the large N c limit or in the large energy limit Q ≫ Λ QCD where Q = {m b , m c , m b − m c }. Data also suggests factorization in the processes B → D * π + π − π − π 0 and B → D * ωπ − , however by themselves neither large N c nor large Q can account for this. Noting that the condition for large energy release inB 0 → D + π − is enforced by the SV limit, m b ≫ m b − m c ≫ Λ, we propose that the combined large N c and SV limits justify factorization in B → D ( * ) X. This combined limit is tested with the B → D * X inclusive decay spectrum measured by CLEO. We also give exact large N c relations among isospin amplitudes forB → D ( * ) X andB → D ( * )D( * ) X, which can be used to test factorization through exclusive or inclusive measurements. Predictions for the modes B → D ( * ) ππ, B → D ( * ) KK and B → D

Threshold resummation for nonleptonic B meson decays

“…Both effects are necessary, especially when the end-point singularity is linear. Considering either of them, though smears the singularity [6,18], does not suppress the soft contribution strongly enough [16]. The results derived in this work provide a useful reference for the study of two-body nonleptonic B meson decays.…”

Soft, collinear, and nonrelativistic modes in radiative decays of very heavy quarkonium

“…Analogously, for the P-wave color octet shape functions, we obtain from the second diagram of Fig. 1 Im͓T (8,3 …”

Heavy-to-light currents at NNLO in SCET and semi-inclusive decay

“…A generic heavy-to-light currentq Γ i b is represented in SCET by a set of non-local "twobody" and "three-body" [3][4][5][6] …”

“…The matrix elements of the currents, usually parameterized by several transition form factors, are also important inputs to the factorization formulae for non-leptonic B decays [1]. In the kinematic region where the hadronic final state has small invariant mass but large energy, softcollinear effective theory (SCET) [2,3] is the appropriate theoretical framework, with which transparent factorization formulae for the heavy-to-light form factors have been derived [4] (see also [5,6]). Thus, the accurate representation of the heavy-to-light currents in SCET is of particular interest.…”