Sea quark effects inBspectroscopy and decay constants

We present comprehensive results for the spectrum and decay constants of hadrons containing a single b quark. The heavy quark is simulated using an $O(1/M)\mathrm{}$ NRQCD action and the light quark using the $O\left(a\right)\mathrm{}$ tadpole-improved clover action on gauge configurations containing two degenerate flavors of sea quarks at ${\beta }^{n_f=2\mathrm{}}=5.6\mathrm{}$ provided by the HEMCGC Collaboration. We present detailed results for the lower lying S and P wave B meson states and the ${\Lambda }_b$ baryon. We find broad agreement with experiment. In addition, we present results for the pseudoscalar and, for the first time, the vector decay constants fully consistent to $O(\alpha /M):$ $f_B=186\mathrm{}\left(5\right)\mathrm{}$ (stat) (19) (pert) (9) (disc) (13) (NRQCD) ${\mathrm{}(+50\mathrm{})(a}^{-1})\hspace{0.5em}\mathrm{MeV},$ $f_B^{*}=181\mathrm{}\left(6\right)\mathrm{}$ (stat) (18) (pert) (9) (disc) (13) (NRQCD) ${\mathrm{}(+55\mathrm{})(a}^{-1})\hspace{0.5em}\mathrm{MeV}$ and $f_{B_s}{/f}_B=1.14\mathrm{}\left(2\right)\mathrm{}$ (stat) $\left(-2\right)\left({\kappa }_s\right).\mathrm{}$ We present an investigation of sea quark effects in the B spectrum and decay constants. We compare our results with those from similar quenched simulations at ${\beta }^{n_f=0\mathrm{}}=\mathrm{6.0.}\mathrm{}$. For the spectrum, the quenched results reproduce the experimental spectrum well and there is no significant difference between the quenched and $n_f=2\mathrm{}$ results. For the decay constants, our results suggest that sea quark effects may be large.