Study of rare b decays with the DELPHI detector at LEP

Physics Letters B, 1996

Four candidates for charmless hadronic B decay are observed in a data sample of four million hadronic Z decays recorded by the aleph detector at lep. The probability that these events come from background sources is estimated to be less than 10 6 . The average branching ratio of weakly decaying B hadrons a mixture of B 0 d , B 0 s and b weighted by their production cross sections and lifetimes, here denoted B into two long-lived charged hadrons pions, kaons or protons is measured to be BrB ! h + h = 1 : 7 +1:0 0:7 0:2 10 5 . The relative branching

2000

Physical Review D, 2002

New data from the BaBar, Belle, and CLEO Collaborations on B decays to two-body charmless final states are analyzed, with the following consequences: (1) The penguin amplitude which dominates the decay B + → π + K * 0 has a magnitude similar to that dominating B + → π + K 0 . The decay B + → π + η, a good candidate for observing direct CP violation, should be detectable at present levels of sensitivity. The decays B + → η ′ K + and B + → ηK * + are sufficiently similar in rate to the corresponding decays B 0 → η ′ K 0 and B 0 → ηK * 0 , respectively, that one cannot yet infer the need for "tree" amplitudes t ′ contributing to the B + but not the B 0 decays. Statistical requirements for observing this and other examples of tree-penguin interference are given. Whereas the B + → η ′ K + and B 0 → η ′ K 0 rates cannot be accounted for by the penguin amplitude p ′ alone but require an additional flavor-singlet penguin contribution s ′ , no such flavor-singlet penguin contribution is yet called for in the decays B + → ηK * + or B 0 → ηK * 0 . Predictions for the rates for B + → η ′ K * + and B 0 → η ′ K * 0 are given which would allow one to gauge the importance of these flavor-singlet penguin amplitudes. *

Physics Letters B, 1995

A search for rare charmless decays of B 0 d and B 0 s mesons has been performed in the exclusive c hannels B 0 d(s) ! , B 0 d (s) ! 0 and B 0 d(s) ! 0 0 . The data sample consisted of three million hadronic Z decays collected by the L3 experiment at LEP from 1991 through 1994. No candidate event has been observed and the following upper limits at 90% condence level on the branching ratios have been set Br(B 0 d ! )<4:110 4 ; Br(B 0 s ! )<1:510 3 ; Br(B 0 d ! 0 )<2:510 4 ; Br(B 0 s ! 0 )<1:010 3 ; Br(B 0 d ! 0 0 ) < 6:0 10 5 ; Br(B 0 s ! 0 0 ) < 2:1 10 4 : These are the rst experimental limits on B 0 d ! and on the B 0 s neutral charmless modes. Submitted to Phys. Lett. B 8 1 I . P h ysikalisches Institut, RWTH, D-52056 Aachen, FRG x III. Physikalisches

Physical Review D, 2002

We report on a study of three-body charmless decays B ϩ →K ϩ h ϩ h Ϫ based on a 29.1 fb Ϫ1 data sample collected with the Belle detector. With no assumptions on the intermediate mechanisms, the following threebody branching fractions have been measured for the first time: