Using a data sample of integrated luminosity ∫ Ldt = 28.9 +/- 1.2 pb-1 of proton-antiproton collisions at a center-of-mass energy s = 1.8 TeV collected with the CDF detector at the Fermilab Tevatron collider, we searched for "penguin" radiative decays of B0d and B0s mesons which involve the flavor-changing neutral-current transition of a b quark into an s quark with the emission of a photon, b→sg . Specifically, we searched for the decays B0d→K*0g, K*0→K+p- and B0s→fg, f→K+K- , as well as for the charge conjugate chains. / In order to collect such decays, we designed a specialized trigger which required information on all the decay products of the B meson decay chain, the first such trigger in a hadron collider environment. This "penguin" trigger collected data during the last quarter of the 1994--1996 data taking period. After all selection criteria, we are left with one candidate B0d→K*0g decay and no B0s→fg candidates in the entire data sample. We then proceed to set upper limits on the branching fractions of the penguin channels. / We exploit the topological similarity between the B&d1;→e-D0 X,D0→K-p + and the penguin decays, by forming ratios of branching fractions between the penguin and the B&d1;→e-D0 X channels. Uncertainties associated with the B meson production cross section, common efficiency corrections and other systematic effects are minimal in the ratio of branching fractions. The uncertainty on the B&d1;→e-D0 X yield is the biggest contribution to the total uncertainty on the penguin branching fraction. We assume equal production rates for B+u and B0d mesons, while the probability of producing B0s mesons relative to B0d mesons, fs/fd, is taken to be 1/3. The inferred upper limits on the ratios of branching fractions are B&parl0;B0 s→fg&parr0;B&parl0; B&d1;→e-D0 X&parr0;<3.5x10-3 at90% C.L. B&parl0;B 0d→K*0g&parr0; B&parl0;B&d1;→e- D0X&parr0;<1.9x10-3 at90%C.L. / Relative branching fraction measurements were combined with the branching fraction measurement of the B&d1;→e-D0 X,D0→K-p + decay chain, B&parl0;B&d1;→e- D0X&parr0;xB&parl0;D0→ K-p+&parr0; = (294 +/- 40) x 10-5, to extract the following absolute branching fraction limits B&parl0;B0s→ fg&parr0;<2.8x10-4 at90%C.L. B&parl0;B0d →K*0g&parr0;<1.5x10-4 at90% C.L. / The upper limit for the B0d→K*0g decay is consistent with the branching fraction measurement reported by the CLEO collaboration, B&parl0;B0d→K*0 g&parr0; = (4.0 +/- 1.9) x 10-5, while the upper limit for the as yet unobserved B0s→fg decay is the most constraining one set to date.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.36626 |
| Date | January 2000 |
| Creators | Kordas, Kostas. |
| Contributors | Ragan, Ken (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Physics.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001746283, proquestno: NQ64593, Theses scanned by UMI/ProQuest. |
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