Using a large sample of D+→K−π+μ+ν decays collected by the FOCUS photoproduction experiment at Fermilab, we present the first measurements of the helicity basis form factors free from the assumption ...of spectroscopic pole dominance. We also present the first information on the form factor that controls the s-wave interference discussed in a previous paper by the FOCUS Collaboration. We find reasonable agreement with the usual assumption of spectroscopic pole dominance and measured form factor ratios.
We apply a genetic programming technique to search for the doubly Cabibbo suppressed decays Λc+→pK+π− and Ds+→K+K+π−. We normalize these decays to their Cabibbo favored partners and find ...BR(Λc+→pK+π−)/BR(Λc+→pK−π+)=(0.05±0.26±0.02)% and BR(Ds+→K+K+π−)/BR(Ds+→K−K+π+)=(0.52±0.17±0.11)% where the first errors are statistical and the second are systematic. Expressed as 90% confidence levels (CL), we find <0.46 and <0.78%, respectively. This is the first successful use of genetic programming in a high energy physics data analysis.
Measurement of the D(s)+ lifetime Yager, P M; Anjos, J C; Bediaga, I ...
Physical review letters,
2005-Jul-29, 20050729, 2005-07-29, Volume:
95, Issue:
5
Journal Article
Peer reviewed
A high statistics measurement of the D(s)+ lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. We describe the analysis of the two decay modes, D(s)+ --> ...phi(1020)pi+ and D(s)+ -->K*(892)0K+, used for the measurement. The measured lifetime is 507.4 +/- 5.5(stat) +/- 5.1(syst) fs using 8961 +/- 105 D(s)+ --> phi(1020)pi+ and 4680 +/- 90 D(s)+ --> K*(892)0K+ decays. This is a significant improvement over the present world average.
A precise determination of the charm-strange baryon Ξc+ lifetime is presented. The data were accumulated by the Fermilab high-energy photoproduction experiment FOCUS. The measurement is made with ...300Ξc+→Ξ−π+π+ decays, 130Ξc+→Σ+K−π+ decays, 45Ξc+→pK−π+ decays and 58Ξc+→Λ0K−π+π+ decays. The Ξc+ lifetime is measured to be 0.439±0.022±0.009 ps.
We present an analysis of the decay D0→K+π− based on FOCUS data. From a sample of 234 signal events, we find a branching ratio of Γ(D0→K+π−)Γ(D0→K−π+)=(0.429−0.061+0.063±0.027)% under the assumptions ...of no mixing and no CP violation. Allowing for CP violation, we find a branching ratio of (0.429±0.063±0.028)% and a CP asymmetry of 0.18±0.14±0.04. The branching ratio for the case of mixing with no CP violation is (0.381−0.163+0.167±0.092)%. We also present limits on charm mixing.
In recent years charm physics has encountered renovated interest; the excellent quality of the data and high statistics allow for unprecedented sensitivity and sophisticated studies never possible ...before. Investigation of decay dynamics in both the hadronic and semileptonic sectors reveals manifestation of quantum mechanical interference and phase effects that allow probing FSI and possible CPV effects. Lifetime measurements at a level of 1% or better can shed light onto the non-spectator contribution to the charm decays, and mixing could represent a possible window to new physics. It is in this context that the results selected from the Focus experiment here have to be accommodated.
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