Measurements of the B -> X-s gamma branching fraction and photon spectrum from a sum of exclusive final states

Using 88.9 million B (B) over bar events collected by the BABAR detector at the Upsilon(4S), we measure the branching fraction for the radiative penguin process B -> X(s)gamma from the sum of 38 exclusive final states. The inclusive branching fraction above a minimum photon energy E-gamma> 1.9 GeV is B(b -> s gamma)=(3.27 +/- 0.18(stat)(-0.40)(+0.55)(syst)(-0.09)(+0.04)(theory))x10(-4). We also measure the isospin asymmetry between B--> X(s (u) over bar)gamma and (B) over bar (0)-> X(s (d) over bar)gamma to be Delta(0-)=-0.006 +/- 0.058(stat)+/- 0.009(syst)+/- 0.024((B) over bar (0)/B-). The photon energy spectrum is measured in the B rest frame, from which moments are derived for different values of the minimum photon energy. We present fits to the photon spectrum and moments which give the heavy-quark parameters m(b) and mu(pi)(2). The fitted parameters are consistent with those obtained from semileptonic B -> X(c)l nu decays, and are useful inputs for the extraction of V-ub from measurements of semileptonic B -> X(u)l nu decays.