Observation of B-s(0)-\u3e K+K- and measurements of branching fractions of charmless two-body decays of B-0 and B-s(0) mesons in pp collisions at root s=1.96 TeV

We search for decays of the type B-(s)(0)-\u3e h(+)h(\u27-) (where h,h(\u27)=K or pi) in 180 pb(-1) of (p) over barp collisions collected at the Tevatron by the upgraded Collider Detector at Fermilab. We report the first observation of the new mode B-s(0)-\u3e K+K- with a yield of 236 +/- 32 events, corresponding to (f(s)/f(d))xB(B-s(0)-\u3e K+K-)/B(B-0 -\u3e K+pi(-))=0.46 +/- 0.08(stat)+/- 0.07(syst), where f(s)/f(d) is the ratio of production fractions of B-s(0) and B-0. We find results in agreement with world averages for the B-0 modes, and set the following new limits at 90% C.L.: B(B-s(0)-\u3e K-pi(+))\u3c 5.6x10(-6) and B(B-s(0)-\u3epi(+)pi(-))\u3c 1.7x10(-6)