M. Boschini

Analysis of the D+, Ds + → K+K-π+ Dalitz plots

Abstract Amplitude analyses of the D + and D s + → K + K − π + Dalitz plots are presented using data collected by the Fermilab high energy photoproduction experiment E687. Our data are fit to a model consisting of a sum of Breit-Wigner amplitudes for the intermediate two-body resonant decay modes. We extract decay fractions and relative phases. These results are used to infer new branching ratios for D + → K + K − π + inclusive as well as the Φπ + and K ∗ (892) 0 K + channels.

First measurement of the lifetime of the omega(c)0.

Abstract We present the first measurement of the lifetime of the Ω c 0 baryon. The data were collected in the Fermilab high energy photoproduction experiment E687. The measured lifetime is τ = 86−20+27(stat.) ± 28(syst.) fr. Thus the Ω c 0 has one of the shorter lifetimes among the weakly decaying singly charmed baryons.

Analysis of the Cabibbo suppressed decay D0 → π−l+ν

Abstract Results for the Cabibbo suppressed semileptonic decays D 0 → π − e + ν and D 0 → π − μ + ν (charge conjugates are implied) are reported by Fermilab photoproduction experiment E687. We find 45.4 ± 13.3 events in the electron mode and 45.6 ± 11.8 in the muon mode. The relative branching ratio BR (D 0 →π − l + v) BR (D 0 →K − l + v) for the combined sample is measured to be 0.101 ± 0.020 (stat.) ± 0.003 (syst.) 14 .

Study of charged hadronic four-body decays of the D0 meson

Abstract Charged hadronic four-body decays of D 0 mesons have been studied in the E687 photoproduction experiment at Fermilab. Branching ratios relative to the D 0 → K − π + π + π − decay mode for the Cabibbo-suppressed decays D 0 → π − π + π − π + , D 0 → K − K + π − π + have been measured and the first evidence of the D 0 → K − K + K − π + decay mode is reported. An analysis of the D 0 → K − K + π − π + resonance structure is also presented.

Search for CP violation in the decays D+ ---> K(S) pi+ and D+ ---> K(S) K+

A high statistics sample of photo-produced charm from the FOCUS(E831) experiment at Fermilab has been used to search for direct CP violation in the decays D+->K_S pi+ and D+ ->K_S K+. We have measured the following asymmetry parameters relative to D+->K-pi+pi+: A_CP(K_S pi+) = (-1.6 +/- 1.5 +/- 0.9)%, A_CP(K_S K+) = (+6.9 +/- 6.0 +/- 1.5)% and A_CP(K_S K+) = (+7.1 +/- 6.1 +/- 1.2)% relative to D+->K_S pi+. The first errors quoted are statistical and the second are systematic. We also measure the relative branching ratios: \Gamma(D+->\bar{K0}pi+)/\Gamma(D+->K-pi+pi+) = (30.60 +/- 0.46 +/- 0.32)%, \Gamma(D+->\bar{K0}K+)/\Gamma(D+->K-pi+pi+) = (6.04 +/- 0.35 +/- 0.30)% and \Gamma(D+->\bar{K0}K+)/\Gamma(D+->\bar{K0}pi+) = (19.96 +/- 1.19 +/- 0.96)%.

Study of higher mass charm baryons decaying to Λc

Abstract We report on the study of charm baryons decaying to Λ c + : Λ c ★+ (2625) → Λ c + π + π − , Λ c ★+ (2593) → Λ c + π + π − , Σ c 0 → Λ c + π − and Σ c ++ → Λ c + π + . We present a confirmation of the state Λ c ∗+ (2593) and determine its mass difference to be M ( Λ c ★+ (2593)) − M ( Λ c + ) = 309.2 ± 0.7 ± 0.3 MeV/ c 2 . We determine the lower limit on the resonant branching ratio to be BR (Λ c ★+ (2593) → Σ c π ± Λ c ★+ (2593) → Λ c + π + π − ) > 0.51 (90% c.l.). We also measure the mass differences M ( Σ c 0 ) − M ( Λ c + ) = 166.6±0.5±0.6 MeV/ c 2 and M ( Σ c ++ ) − M ( Λ c + ) = 167.6±0.6±0.6 MeV/ c 2 . Finally, we measure the relative photoproduction cross sections for Λ c ★+ and Σ c with respect to the (inclusive) photoproduction cross section for Λ c + .

Doubly and singly Cabibbo suppressed charm decays into the K+π-π+ final state

Abstract Branching ratios and upper limits at 90% confidence level for D+ and Ds+ → K+π−π+ decays collected in Fermilab photoproduction experiment E-687 are reported. The D+ results are: Γ(D + → K + π − π + ) Γ(D + → K − π + π + ) = (7.2 ± 2.3 ± 1.7) × 10 −3 , Γ(D + → K ∗0 (892)π + ) Γ(D + → K − π + π + ) , and Γ(D + → K + ϱ 0 (770)) Γ(D + → K − π + π + ) . The Ds+ results are: Γ(D s + → K + π − π + ) Γ(D s + → Φ(1020)π + ) = 0.28 ± 0.06 ± 0.05 , Γ(D s + → K ∗0 (892)π + Γ(D s + → Φ(1020)π + ) = 0.18 ± 0.05 ± 0.04 , and Γ(D s + → K + ϱ 0 (770)) Γ(D s + → Φ(1020)π + ) .

Observation of the vector meson Cabibbo suppressed decay D+ → ρ0π+ν

Abstract We report on the first statistically significant observation of the vector meson Cabibbo suppressed semileptonic decay D+ → ρ0μ+ν. We measure the branching ratio of the decay mode D+ → ρ0μ+ν (plus possible unobserved γ from D+ → η′μ+ν, η′ → γρ0) with respect to the decay mode D + → K ∗0 μ + ν to be BR (D + → ρ 0 μ + ν) BR (D + → K ∗0 μ + ν) = 0.079 ± 0.019 ( stat ) ± 0.013 ( syst ) . Data were collected by Fermilab photoproduction experiment E687.

Search for the decay of D+ and Ds+ mesons to three charged kaons

Abstract We report the results of a search for the doubly Cabibbo suppressed decays D+ → K+K−K+ and D+ → ΦK+, and the singly Cabibbo suppressed decays Ds+ → K+K−K+ and Ds+ → ΦK+. Our measurements are all consistent with zero branching ratio, and we set 90% confidence level upper limits on the relative D+ branching ratios: BR(ΦK + ) BR(Φπ + ) , BR(K + K − K + ) BR(Φπ + ) and BR(K + K − K + ) BR(K − π + π + ) , and the relative Ds+ branching ratios: BR(ΦK + ) BR(Φπ + ) and BR(K + K − K + ) BR(Φπ + ) . The data were accumulated by the Fermilab high energy photoproduction experiment E687.

Study of charged hadronic five-body decays of the D+ and Ds+ mesons

Abstract Charged hadronic five-body decays of D + and D s + mesons have been studied in the E687 photoproduction experiment at Fermilab. We report the first compelling evidence of the decay mode D + , D s + → π − π − β + π + π + and the measurements of the decays D + → K − π − π + π + π + , D s + → K − K + π − π + π + and D s + → φπ − π + π + . An analysis of the D + → K − π − π + π + π + resonance structure is also presented.