First Observation and Measurement of the Branching Fraction for the Decay B[subscript s][superscript 0] → D[subscript s][superscript ∗] ∓ K[superscript ±]

The first observation of the B[subscript s][superscript 0] → D[subscript s][superscript ∗] ∓ K[superscript ±] decay is reported using 3.0 fb[superscript −1] of proton-proton collision data collected by the LHCb experiment. The D [subscript s][superscript ∗ ∓] mesons are reconstructed through the decay chain D[subscript s][superscript ∗ ∓] → γD[subscript s][superscript ∓] (K[superscript ∓] K[superscript ±] π[superscript ∓]). The branching fraction relative to that for B[subscript s][superscript 0] → D[subscript s][superscript ∗ −] π[superscript +] decays is measured to be B(B[superscript 0][subscript s] →D[subscript s][superscript ∗][superscript ∓]K[superscript ±])/B(B[superscript 0][superscript s]→D[superscript ∗-][subscript s]π[superscript +])=0.068±0.005+0.003−0.002, where the first uncertainty is statistical and the second is systematic. Using a recent measurement of B(B[superscript 0][subscript s]→D[subscript s][superscript ∗−]π[superscript +]) , the absolute branching fraction of B[subscript s][superscript 0] → D[subscript s][superscript ∗ ∓] K[superscript ±] is measured as B(B[superscript 0][subscript s]→D[subscript s][superscript ∗∓]K[superscript ±])=(16.3±1.2(stat)+0.7−0.5(syst)±4.8(norm))×10[superscript −5], where the third uncertainty is due to the uncertainty on the branching fraction of the normalisation channel. Keywords: Branching fraction, B physics, Flavor physics, Hadron-Hadron ScatteringNational Science Foundation (U.S.