Quenched Chiral Corrections to Heavy-Light Decay Constants at Order 1/M
  Quenched chiral perturbation is used to study the decay constants for heavy-light mesons beyond the leading order in 1/M. The results are used to estimate the error in quenched lattice calculations of the decay constants. For the double ratio $R_1 = ( f_{D_s}/f_D) / (f_{B_s}/f_B)$ we find that the error is small, conservatively 6%, but likely smaller. We also find that quenching decreases the ratio $f_{D_s}/f_D$ relative to the unquenched theory. 
Michael J. Booth