Georg Viehhauser

Abstract:

Using data recorded with the CLEO II and CLEO II.V detector configurations at the Cornell Electron Storage Rings, we report the first observation and mass measurement of the Sigma(*+)(c) charmed baryon, and an updated measurement of the mass of the Sigma(+)(c) baryon. We find M(Sigma(*+)(c))-M(Lambda(+)(c)) = (231.0+/-1.1+/-2.0) MeV, and M(Sigma(+)(c))-M(Lambda(+)(c)) = (166.4+/-0.2+/-0.3) MeV, where the errors are statistical and systematic, respectively.

Abstract:

Using 13.6 fb -1 of continuum two-jet e + e - →cc events collected with the CLEO detector, we have searched for baryon number correlations at the primary quark level. We have measured the likelihood for a A c+ charmed baryon to be produced in the hemisphere opposite a A c- relative to the likelihood for a A c- charmed baryon to be produced opposite an anticharmed meson D; in all cases, the reconstructed hadrons must have momentum greater than 2.3 GeV/c. We find that, given a A c- (reconstructed in five different decay modes), a Ac+ is observed in the opposite hemisphere (0.72±0.11)% of the time (not corrected for efficiency). By contrast, given a D in one hemisphere, a A c+ is observed in the opposite hemisphere only (0.21 ±0.02)% of the time. Normalized to the total number of either A c- or D "tags," it is therefore 3.52±0.45±0.42 times more likely to find a A c+ opposite a A~ than a D meson. This enhancement is not observed in the JETSET 7.3 e + e - →cc Monte Carlo simulation. ©2001 The American Physical Society.

Abstract:

We report on a search for the decay B+→D*+Ks0 and its charge conjugate with the CLEO detector at the Cornell Electron Storage Ring (CESR). No candidates are found in 9.10 fb-1 of data. The background is estimated to be 0.29±0.05 leading to an upper limit B(B+→D*+K0) = 9.5×10-5 (90% confidence level). ©2001 The American Physical Society.

Abstract:

In a sample of 9.66x10(6)B&Bmacr; pairs collected with the CLEO detector we make the first observation of B decays to an eta(c) and a kaon. We measure branching fractions B(B+-->eta(c)K+) = (0.69(+0.26)(-0.21)+/-0.08+/-0.20)x10(-3) and B(B degrees -->eta(c)K degrees ) = (1.09(+0.55)(-0.42)+/-0.12+/-0.31)x10(-3), where the first error is statistical, the second is systematic, and the third is from the eta(c) branching fraction uncertainty. From these we extract the eta(c) decay constant in the factorization approximation, f(eta(c)) = 335+/-75 MeV. We also search for B decays to a chi(c0) and a kaon. No evidence for a signal is found and we set 90% C.L. upper limits: B(B+-->chi(c0)K+)<4.8x10(-4) and B(B degrees -->chi(c0)K degrees )<5.0x10(-4).