[Show abstract][Hide abstract] ABSTRACT: We study the decay of mesons into final states involving a and report the discovery of Cabibbo suppressed decay modes (179±36 events) and (113±26 events). The branching fraction ratios for the new modes are and .
[Show abstract][Hide abstract] ABSTRACT: We present a search for a pentaquark decaying strongly to Ξ−π− in γN collisions at a center-of-mass energy up to 25 GeV/c2. Finding no evidence for such a state in the mass range of 1480 MeV/c2 to 2400 MeV/c2, we set limits on the yield and on the cross section times branching ratio relative to Ξ∗0(1530).
[Show abstract][Hide abstract] ABSTRACT: 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.
[Show abstract][Hide abstract] ABSTRACT: We present a Kπ mass spectrum analysis of the four-body semileptonic charm decay D+→K−π+μ+ν in the range of 0.65 GeV/c2<mKπ<1.5 GeV/c2. We observe a non-resonant contribution of with respect to the total D+→K−π+μ+ν decay. For the K∗0(892) resonance, we obtain a mass of , a width of , and a Blatt–Weisskopf damping factor parameter of . We also report 90% CL upper limits of 4% and 0.64% for the branching ratios and , respectively.
[Show abstract][Hide abstract] ABSTRACT: 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.
[Show abstract][Hide abstract] ABSTRACT: We present a Kπ mass spectrum analysis of the four-body semileptonic
D→Kπμν in the
range of 0.65 GeV/c<m<1.5 GeV/c.
We observe a non-resonant contribution of 5.30±0.74-0.96+0.99%
with respect to the total
For the K892 resonance, we obtain a mass of
895.41±0.32-0.43+0.35 MeV/c, a width of
47.79±0.86-1.06+1.32 MeV/c, and a Blatt Weisskopf
damping factor parameter of 3.96±0.54-0.90+1.31 GeV.
We also report 90% CL upper limits of 4% and 0.64% for the branching
Physics Letters B 07/2005; 621:72-80. · 4.57 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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 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 . We also present limits on charm mixing.
[Show abstract][Hide abstract] ABSTRACT: Using data from the FOCUS (E831) experiment at Fermilab, we present a new measurement for the Cabibbo-suppressed decay mode D0→K+K−π+π−. We measure: Γ(D0→K+K−π+π−)/Γ(D0→K−π−π+π+)=0.0295±0.0011±0.0008. An amplitude analysis has been performed in order to determine the resonant substructure of this decay mode. The dominant components are the decays D0→K1+(1270)K−, D0→K1+(1400)K− and D0→ρ0(770)ϕ(1020).
[Show abstract][Hide abstract] ABSTRACT: Using data collected by the fixed target Fermilab experiment FOCUS, we present several first measurements for the semileptonic decay . Using a model that includes a s-wave component, we measure the form factor ratios to be rv=1.71±0.68±0.34 and r2=0.91±0.37±0.10 and the s-wave amplitude to be A=0.35±0.22±0.05 GeV−1. Finally, we measure the vector semileptonic branching ratio .
[Show abstract][Hide abstract] ABSTRACT: Using data from the FOCUS experiment (FNAL–E831), we study the decay of baryons into final states containing a Λ hyperon. The branching fractions of into Λπ+, Λπ+π+π− and relative to that into pK−π+ are measured to be 0.217±0.013±0.020, 0.508±0.024±0.024 and 0.142±0.018±0.022, respectively. We also report new measurements of , and . Further, an analysis of the subresonant structure for the decay mode is presented.
[Show abstract][Hide abstract] ABSTRACT: We review genetic programming principles, their application to FOCUS data samples, and use the method to study the doubly Cabibbo suppressed decay D+→K+π+π- relative to its Cabibbo favored counterpart, D+→K-π+π+. We find that this technique is able to improve upon more traditional analysis methods. To our knowledge, this is the first application of the genetic programming technique to High Energy Physics data.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 01/2005;
[Show abstract][Hide abstract] ABSTRACT: Using data from the FOCUS (E831) experiment, we have searched for T violation in charm meson decays using the four-body decay channels D0→K−K+π−π+, , and . The T violation asymmetry is obtained using triple-product correlations and assuming the validity of the CPT theorem. We find the asymmetry values to be ATviol(D0)=0.010±0.057(stat.)±0.037(syst.), ATviol(D+)=0.023±0.062(stat.)±0.022(syst.), and . Each measurement is consistent with no T violation. New measurements of the CP asymmetries for some of these decay modes are also presented.
[Show abstract][Hide abstract] ABSTRACT: We apply a genetic programming technique to search for the doubly Cabibbo suppressed decays and . We normalize these decays to their Cabibbo favored partners and find and 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.
[Show abstract][Hide abstract] ABSTRACT: We present a search for a charmed pentaquark decaying strongly to D(∗)−p. Finding no evidence for such a state, we set limits on the cross-section times branching ratio relative to D∗− and D− under particular assumptions about the production mechanism.
[Show abstract][Hide abstract] ABSTRACT: Using data from the FOCUS experiment (FNAL-E831), we report on the decay of D0 mesons into final states containing more than one . We present evidence for two Cabibbo favored decay modes, and , and measure their combined branching fraction relative to to be . Further, we report new measurements of , , and where the first error is statistical and the second is systematic.