Measurement of the lambda(+)(c) lifetime

The Lambda+c lifetime is measured using 9.0 fb(-1) of e+e- annihilation data collected on or just below the Upsilon(4S) resonance with the CLEO II.V detector at CESR. Using an unbinned maximum likelihood fit, the Lambda+c lifetime is measured to be 179.6+/-6.9(stat)+/-4.4(syst) fs. The precision of this colliding beam measurement is comparable to other measurements, which are based on fixed-target experiments, with different systematic uncertainties.     

Measurement of the lifetime difference between Bs mass eigenstates

We present measurements of the lifetimes and polarization amplitudes for B(0)(s)-->J/psiphi and B(0)(d)-->J/psiK(*0) decays. Lifetimes of the heavy and light mass eigenstates in the B(0)(s) system are separately measured for the first time by determining the relative contributions of amplitudes with definite CP as a function of the decay time. Using 203+/-15 B(0)(s) decays we obtain tau(L) = (1.05(+0.16)(-0.13) +/- 0.02) ps and tau(H) = (2.07(+0.58)(-0.46) +/- 0.03) ps. Expressed in terms of the difference DeltaGamma(s) and average Gamma(s), of the decay rates of the two eigenstates, the results are DeltaGamma(s)/Gamma(s) = (65(+25)(-33) +/- 1)% and DeltaGamma(s) = (0.47(+0.19)(-0.24) +/- 0.01) ps(-1).     

Remarks on the lifetime of charmed baryonΛ c +

The interference andW-exchange contributions toΛ _c ⁺ inclusive nonleptonic decay rate are expressed in terms of matrix elements of effective fourquark operators and evaluated in the MIT bag model. It is found that although theW-exchange is not necessarily subject to helicity and color suppression, it does not suffice to explain the measured lifetime ofΛ _c ⁺. The observed semileptonic branching ratio ofΛ _c ⁺, however, requires that its inclusive decay rate be dominated by the nonspectator contribution and thus theW-exchange be substantially enhanced by some nonperturbative effects. The implication for exclusive two-body decays ofΛ _c ⁺ is briefly discussed.     

Measurement of mass and lifetime of hadronically produced charmed F mesons

We have observed three unique decays of F mesons into KKπ and five unique decays of D mesons into KKπ using the NA11 spectrometer together with a telescope of high-resolution silicon microstrip detectors. The mass value obtained for the F meson is (1975 ± 4) MeV, the lifetime (3.2±_1.3^3..0)×10^?13 s.     

Measurement of the lifetime of the first 2+ state in 124Ba

The lifetime of the first 2⁺ state in the nucleus ¹²⁴Ba has been measured by γ-γ coincidence recoil-distance Doppler shift method. The ¹⁰⁹Ag(¹⁹F, 4n)¹²⁴Ba reaction at a beam energy of 75 MeV was employed to populate excited states in ¹²⁴Ba. The mean lifetime was determined to be 275(12) ps using the differential decay curve method. The value of B(E2;0₁ ⁺→ 2₁ ⁺) for ¹²⁴Ba deduced from the lifetime is in reasonable agreement with the prediction of the proton-neutron interacting boson model(IBM-2) without Pauli blocking effect. Received: 23 February 1998     

Measurement of the τ lifetime

Using the 3-prong decays of τ leptons observed at the CELLO detector at PETRA, the τ lifetime is determined to be 4.7(_?2.9^+3.9)×10^?13s.     

Measurement of the Bc+ meson lifetime using the decay mode Bc+ --> J/Psie+nue

We present a measurement of the Bc+ meson lifetime in the decay mode Bc+ --> J/Psie+nue using the Collider Detector at Fermilab II detector at the Fermilab Tevatron Collider. From a sample of about of 360 pb(-1) of pp collisions at square root of s = 1.96 TeV, we reconstruct J/Psie+ pairs with invariant mass in the kinematically allowed range 4< M(J/Psie) < 6 GeV/c2. A fit to the decay-length distribution of 238 signal events yields a measured Bc+ meson lifetime of 0.463(-0.065)(+0.073)(stat) +/- 0.036(syst) ps.