Richard J. S. Morrison

Measurement of the D0, D+ and D(s)+ Lifetimes

We have measured the lifetimes of the D/sup 0/, D/sup +/, and D/sub s//sup +/ mesons which were produced by a high-energy photon beam incident on beryllium. Using the Fermilab Tagged Photon Spectrometer with a silicon-microstrip vertex detector we have collected 10/sup 8/ events from which we have extracted about 4200 D/sup 0/ decays in the K/sup -/..pi../sup +/ and K/sup -/..pi../sup +/..pi../sup -/..pi../sup +/ modes, 3000 D/sup +/ into the K/sup -/..pi../sup +/..pi../sup +/ channel, and a total of 230 D/sub s//sup +/ into phi..pi../sup +/ and K-bar/sup *//sup 0/K/sup +/. From an analysis of these events we have determined the lifetimes for the D/sup 0/, D/sup +/, and D/sub s//sup +/ to be 0.422 +- 0.008 +- 0.010, 1.090 +- 0.030 +- 0.025, and 0.47 +- 0.04 +- 0.02 psec, respectively

Study of the decays D r arrow K 3. pi

We report measurements of the decays {ital D}{sup 0}{r arrow}{ital K}{sup {minus}}{pi}{sup +}{pi}{sup +}{pi}{sup {minus}}, {ital D}{sup +}{r arrow}{ital {bar K}}{sup 0}{pi}{sup +}{pi}{sup +}{pi}{sup {minus}}, {ital D}{sup +}{r arrow}{ital K}{sup {minus}}{pi}{sup +}{pi}{sup +}{pi}{sup 0}, and {ital D}{sup 0}{r arrow}{ital {bar K}}{sup 0}{pi}{sup +}{pi}{sup {minus}}{pi}{sup 0} from Fermilab photoproduction experiment E691. A complete resonant substructure analysis is used to determine the relative fractions and phases of amplitudes contributing to the decays {ital D}{sup 0}{r arrow}{ital K}{sup {minus}}{pi}{sup +}{pi}{sup +}{pi}{sup {minus}}, {ital D}{sup +}{r arrow}{ital {bar K}}{sup 0}{pi}{sup +}{pi}{sup +}{pi}{sup {minus}}, and {ital D}{sup +}{r arrow}{ital K}{sup {minus}}{pi}{sup +}{pi}{sup +}{pi}{sup 0}.

Resonance structure of {tau}{sup -}{yields}K{sup -}{pi}{sup +}{pi}{sup -}{nu}{sub {tau}} decays

Using a sample of 4.7/fb integrated luminosity accumulated with the CLEO II detector at the Cornell Electron Storage Ring (CESR), we investigate the mass spectrum and resonant structure in tau->Kpipi decays. We measure the relative fractions of K1(1270) and K1(1400) resonances in these decays, as well as the K1 masses and widths. Our fitted K1 resonances are somewhat broader than previous hadroproduction measurements, and in agreement with recent LEP results from tau decay. The larger central value of our measured width supports models which attribute the small tau->Kpipi branching fraction to larger K1 widths than are presently tabulated. We also determine the Ka-Kb mixing angle theta_K.

Study of the decays D r arrow K sup 0. pi. sup + and D r arrow K sup 0 K sup +

We report measurements of the decays {ital D}{sup +}{r arrow}{ital {bar K}}{sup 0}{pi}{sup +}, {ital D}{sup +}{r arrow}{ital {bar K}}{sup 0}{ital K}{sup +}, and {ital D}{sub {ital s}}{sup +}{r arrow}{ital {bar K}}{sup 0}{ital K}{sup +} from Fermilab photoproduction experiment E691. The relative branching fractions obtained are {ital B}({ital D}{sup +}{r arrow}{ital {bar K}}{sup 0}{pi}{sup +})/{ital B}({ital D}{sup +}{r arrow}{ital K}{sup {minus}}{pi}{sup +}{pi}{sup +})=0.274{plus minus}0.030{plus minus}0.031, {ital B}({ital D}{sup +}{r arrow}{ital {bar K}}{sup 0}{ital K}{sup +})/{ital B}({ital D}{sup +}{r arrow}{ital {bar K}}{sup 0}{pi}{sup +})=0.271{plus minus}0.065{plus minus}0.039, and {ital B}({ital D}{sub {ital s}}{sup +}{r arrow}{ital {bar K}}{sup 0}{ital K}{sup +})/{ital B}({ital D}{sub {ital s}}{sup +}{r arrow}{phi}{pi}{sup +})=1.15{plus minus}0.31{plus minus}0.19.

A Study of the Semileptonic Decay Mode D0 ---> K- e+ Electron-neutrino

We present an analysis of the exclusive semileptonic decay mode D/sup 0/ ..-->.. K/sup -/e/sup +/nu/sub e/. We have measured the ratio of decay rates GAMMA(D/sup 0/ ..-->.. K/sup -/e/sup +/nu/sub e/)/GAMMA(D/sup 0/ ..-->.. K/sup -/..pi../sup +/). After correcting for the reconstruction efficiencies and subtracting the contribution from other decay modes we have found the ratio to be equal to 0.77 +- 0.12(stat) +- 0.13(syst).