The performance for B$^{0}_{s} \rightarrow J/\psi\phi$ and B$^{0} \rightarrow J/\psi K^{0}_{s}$ at LHCb

At LHCb the B/sub s//sup 0/ to J/ psi phi decay will be used to determine the B/sub s//sup 0/ mixing phase sin phi /sub s/ and the decay width difference Delta Gamma /sub s/, while the B/sup 0/ to J/ psi K/sub S//sup 0/ decay will be used to determine the B/sup 0/ mixing phase sin phi /sub d/. A detailed GEANT Monte-Carlo simulation was performed to study the performance at LHCb for these decay channels. The results were used in a 'toy' MC to estimate the sensitivity for sin phi /sub s/, Delta Gamma /sub s// Gamma /sub s/, and sin phi /sub d/. The precisions that will be reached after one year of LHCb for sin phi /sub s/, Delta Gamma /sub s// Gamma /sub s/, and sin phi /sub d/ are 0.064, 0.018, and 0.022, respectively. (7 refs).