# First observation of $\barB^0_s \to D_s^\pm K^\mp$ and measurement of the ratio of branching fractions B$(\barB^0_s\to D_s^\pm K^\mp$ /B$(\barB^0_s\to D_s^+ \pi^-)$

Victoria Martin, CDF Collaboration

Research output: Contribution to journalArticlepeer-review

## Abstract

A combined mass and particle identification fit is used to make the first observation of the decay Bs --> Ds K and measure the branching fraction of Bs --> Ds K relative to Bs --> Ds pi. This analysis uses 1.2 fb^-1 integrated luminosity of pbar-p collisions at sqrt(s) = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron collider. We observe a Bs --> Ds K signal with a statistical significance of 8.1 sigma and measure Br(Bs --> Ds K)/Br(Bs --> Ds pi) = 0.097 +- 0.018(stat) +- 0.009(sys).
Original language English Physical Review Letters 103 https://doi.org/10.1103/PhysRevLett.103.191802 Published - 2009

• hep-ex