arXiv subjects
Publications and source records attributed to FOCUS collaboration.
Using data collected by the high energy photoproduction experiment FOCUS at Fermilab we study the doubly and singly Cabibbo suppressed decays D+ and Ds+ --> K+ pi+ pi-. Branching ratios and Dalitz plot analyses are performed.
Using data collected by the fixed target Fermilab experiment FOCUS, we measure the branching ratios of the Cabibbo favored decays $Ξ_c^+ \to Σ^+K^-π^+$, $Ξ_c^+ \to Σ^+ \bar{K}^{*}(892)^0$, and $Ξ_c^+ \to Λ^0K^-π^+π^+$ relative to $Ξ_c^+ \to Ξ^-π^+π^+$ to be $0.91\pm0.11\pm0.04$, $0.78\pm0.16\pm0.06$, and $0.28\pm0.06\pm0.06$, respectively. We report the first observation of the Cabibbo suppressed decay $Ξ_c^+ \to Σ^+K^+K^-$ and we measure the branching ratio relative to $Ξ_c^+ \to Σ^+K^-π^+$ to be $0.16\pm0.06\pm0.01$. We also set 90% confidence level upper limits for $Ξ_c^+ \to Σ^+ ϕ$ and $Ξ_c^+ \to Ξ^*(1690)^0(Σ^+ K^-) K^+$ relative to $Ξ_c^+ \to Σ^+K^-π^+$ to be 0.12 and 0.05, respectively. We find an indication of the decays $Ξ_c^+ \to Ω^-K^{+}π^+$ and $Ξ_c^+ \to Σ^{*}(1385)^+ \bar{K}^0$ and set 90% confidence level upper limits for the branching ratios with respect to $Ξ_c^+ \to Ξ^-π^+π^+$ to be 0.12 and 1.72, respectively. Finally, we determine the 90% C.L. upper limit for the resonant contribution $Ξ_c^+ \to Ξ^{*}(1530)^0 π^+$ relative to $Ξ_c^+ \to Ξ^-π^+π^+$ to be 0.10.
The FOCUS experiment(FNAL-E831) has used two channels, $Ω^- π^+$ and $Ξ^-K^- π^+ π^+$,to measure the lifetime of the $Ω_c^0$ charmed baryon. From a sample of $64 \pm 14$ signal events at a mass of 2.698 GeV/$c^2$, we measure an $Ω_c^0$ lifetime of $72 \pm 11$ (stat.) $\pm 11$ (sys.) fs, substantially improving upon the current world average.
We have studied hadronic four-body decays of $D^+$ and $D^+_s$ mesons with a $K_S$ in the final state using data recorded during the 1996-1997 fixed-target run at Fermilab high energy photoproduction experiment FOCUS. We report a new branching ratio measurement of $Γ(D^+\to K_S K^-π^+π^+)/Γ(D^+\to K_S π^+π^+π^-)=0.0768\pm0.0041\pm0.0032$. We make the first observation of three new decay modes with branching ratios $Γ(D^+\to K_S K^+π^+π^-)/Γ(D^+\to K_S π^+π^+π^-)=0.0562\pm0.0039\pm0.0040$, $Γ(D^+\to\K_S K^+ K^-π^+)/Γ(D^+\to K_S π^+π^+π^-)=0.0077\pm0.0015\pm0.0009$, and $Γ(D^+_s\to K_S K^+π^+π^-)/Γ(D^+_s\to K_S K^-π^+π^+)=0.586\pm0.052\pm0.043$, where in each case the first error is statistical and the second error is systematic.