Experimental investigation of the two-photon widths of the chi(c0) and the chi(c2) mesons.
Phys Rev Lett 87:6 (2001) 061801
Abstract:
Using 12.7 fb(-1) of data collected with the CLEO detector at CESR, we observed two-photon production of the cc states chi(c0) and chi(c2) in their decay to pi(+)pi(-)pi(+)pi(-). We measured gamma(gammagamma)(chi(c))xB(chi(c)-->pi(+)pi(-)pi(+)pi(-)) to be 75+/-13(stat)+/-8(syst) eV for the chi(c0) and 6.4+/-1.8(stat)+/-0.8(syst) eV for the chi(c2), implying gamma(gammagamma)(chi(c0)) = 3.76+/-0.65(stat)+/-0.41(syst)+/-1.69(br) keV and gamma(gammagamma)(chi(c2)) = 0.53+/-0.15(stat)+/-0.06(syst)+/-0.22(br) keV. Also, cancellation of dominant experimental and theoretical uncertainties permits a precise comparison of gamma(gammagamma)(chi(c0))/gamma(gammagamma)(chi(c2)), evaluated to be 7.4+/-2.4(stat)+/-0.5(syst)+/-0.9(br), with QCD-based predictions.Bounds on the CP asymmetry in b --> sgamma decays.
Phys Rev Lett 86:25 (2001) 5661-5665
Abstract:
We have measured the CP asymmetry A(CP) identical with[gamma(b-->sgamma)-gammab-->sgamma)]/[gamma(b-->sgamma)+gamma(b-->sgamma)] to be A(CP) = (-0.079+/-0.108+/-0.022) (1.0+/-0.030), implying that, at 90% confidence level, A(CP) lies between -0.27 and +0.10. These limits rule out some extreme non-standard-model predictions, but are consistent with most, as well as with the standard model.Bounds on the CP asymmetry in like-sign dileptons from B(0)B*(0) meson decays.
Phys Rev Lett 86:22 (2001) 5000-5003
Abstract:
We have measured the charge asymmetry in like-sign dilepton yields from B(0)B*(0) meson decays using the CLEO detector at the Cornell Electron Storage Ring. We find a(0)(ll) identical with[N(l(+)l(+))-N(l(-)l(-))]/[N(l(+)l(+))+N(l(-)l(-))] = +0.013+/-0.050+/-0.005. We combine this result with a previous, independent measurement and obtain Re(epsilon(B))/(1+ the absolute value of epsilon(B)(2)) = +0.0035+/-0.0103+/-0.0015 (uncertainties are statistical and systematic, respectively) for the CP impurity parameter, epsilon(B).Observation of new states decaying into Λc +π-π+
Physical Review Letters 86:20 (2001) 4479-4482
Abstract:
The spectrum of charmed baryons consisting of a charmed quark and two light quarks denoted by Ac and σc baryons were investigated. The sample used in the investigation corresponds to an integrated luminosity 13.7/fb from the data taken on the Y(4S) resonance and in the continuum at energies just below the Y(4S). A broad state with an invariant mass roughly above 480 MeV above that of the Ac baryon and a narrow state with an invariant mass of 596 MeV above the Ac mass were found.Observation of new states decaying into Lambda+(c)pi(-)pi(+).
Phys Rev Lett 86:20 (2001) 4479-4482