Lattice Study of Spectator Effects in b-hadron Decays

The Heavy Quark Expansion (HQE) gives an expansion of inclusive decay rates of b-hadrons as a simultaneous series in α_s and 1/m_b, in terms of perturbatively defined coefficients and non-perturbative matrix elements. Spectator effects arise from the dimension-6 operators in the HQE in which along with the heavy quark, a light spectator quark from the hadron participates in the weak decay. In this work, we provide a lattice determination of the bare matrix elements that contribute to the spectator effects for the B⁺-meson, B_d-meson and the Λ_b-baryon. The computations were performed on two separate lattice spacings of the RBC-UKQCD (2+1)-flavor Domain Wall Fermion ensembles. Renormalization and continuum extrapolation of the matrix elements have not yet been computed, and are left to future work.