Showing papers by "A. M. Lopez published in 2002"
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, University of Illinois at Urbana–Champaign5, Indiana University6, Korea University7, Kyungpook National University8, University of Milan9, University of North Carolina at Chapel Hill10, University of Puerto Rico11, University of South Carolina12, University of Tennessee13, Vanderbilt University14, University of Wisconsin-Madison15
TL;DR: In this article, the authors present evidence for a small even spin K−π+ amplitude that interferes with the dominant K ∗0 component in the D+→K−π +μ+ν final state.
61 citations
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, University of Illinois at Urbana–Champaign5, Indiana University6, Korea University7, University of Milan8, University of North Carolina at Asheville9, University of Puerto Rico at Mayagüez10, University of South Carolina11, University of Tennessee12, Vanderbilt University13, University of Wisconsin-Madison14
21 May 2002-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the authors describe the algorithm used to identify charged tracks in the fixed-target charm-photoproduction experiment FOCUS, and contrast this approach with that used in their preceding experiment E687.
Abstract: We describe the algorithm used to identify charged tracks in the fixed-target charm-photoproduction experiment FOCUS. We begin by describing the new algorithm and contrast this approach with that used in our preceding experiment — E687. We next illustrate the algorithm's performance using physics signals. Finally, we briefly describe some of the methods used to monitor the quantum efficiency and noise of the Cherenkov cells.
59 citations
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, University of Illinois at Urbana–Champaign5, Indiana University6, Korea University7, University of Milan8, University of North Carolina at Asheville9, University of Puerto Rico at Mayagüez10, University of South Carolina11, University of Tennessee12, Vanderbilt University13, University of Wisconsin-Madison14
21 May 2002-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, various techniques developed in the Fermilab Wideband Experiments, E687 and FOCUS, were described to reconstruct long-lived states, all of which involve modifications to standard tracking techniques.
Abstract: We describe the various techniques developed in the Fermilab Wideband Experiments, E687 and FOCUS, to reconstruct long-lived states The techniques all involve modifications to standard tracking techniques and are useful to report for future experiments
29 citations
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, University of Illinois at Urbana–Champaign5, Indiana University6, Korea University7, Kyungpook National University8, University of Milan9, University of North Carolina at Chapel Hill10, University of Puerto Rico at Mayagüez11, University of South Carolina12, University of Tennessee13, Vanderbilt University14, University of Wisconsin-Madison15
TL;DR: In this paper, a large sample of D + → K − π + μ + ν decays collected by the FOCUS photoproduction experiment at Fermilab was used to obtain semileptonic form factor ratios.
28 citations
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, University of Illinois at Urbana–Champaign5, Indiana University6, Korea University7, University of Milan8, University of North Carolina at Chapel Hill9, University of Puerto Rico at Mayagüez10, University of South Carolina11, University of Tennessee12, Vanderbilt University13, University of Wisconsin-Madison14
TL;DR: In this paper, 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+.
Abstract: 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)%.
26 citations
TL;DR: In this paper, a high-statistics sample of photoproduced charm from the FOCUS experiment has been used to search for direct CP violation in the decay rates for the following asymmetry parameters relative to
Abstract: A high-statistics sample of photoproduced charm from the FOCUS experiment has been used to search for direct CP violation in the decay rates for ${D}^{+}\ensuremath{\rightarrow}{K}_{S}{\ensuremath{\pi}}^{+}$ and ${D}^{+}\ensuremath{\rightarrow}{K}_{S}{K}^{+}$. We have measured the following asymmetry parameters relative to ${D}^{+}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{+}$: ${A}_{\mathrm{CP}}({K}_{S}{\ensuremath{\pi}}^{+})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}(\ensuremath{-}1.6\ifmmode\pm\else\textpm\fi{}1.5\ifmmode\pm\else\textpm\fi{}0.9)%$, ${A}_{\mathrm{CP}}({K}_{S}{K}^{+})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}(+6.9\ifmmode\pm\else\textpm\fi{}6.0\ifmmode\pm\else\textpm\fi{}1.5)%$, and ${A}_{\mathrm{CP}}({K}_{S}{K}^{+})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}(+7.1\ifmmode\pm\else\textpm\fi{}6.1\ifmmode\pm\else\textpm\fi{}1.2)%$ relative to ${D}^{+}\ensuremath{\rightarrow}{K}_{S}{\ensuremath{\pi}}^{+}$. We have also measured the relative branching ratios and found $\ensuremath{\Gamma}({D}^{+}\ensuremath{\rightarrow}{\overline{K}}^{0}{\ensuremath{\pi}}^{+})/\ensuremath{\Gamma}({D}^{+}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{+})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}(30.60\ifmmode\pm\else\textpm\fi{}0.46\ifmmode\pm\else\textpm\fi{}0.32)%$, $\ensuremath{\Gamma}({D}^{+}\ensuremath{\rightarrow}{\overline{K}}^{0}{K}^{+})/\ensuremath{\Gamma}({D}^{+}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{+})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}(6.04\ifmmode\pm\else\textpm\fi{}0.35\ifmmode\pm\else\textpm\fi{}0.30)%$, and $\ensuremath{\Gamma}({D}^{+}\ensuremath{\rightarrow}{\overline{K}}^{0}{K}^{+})/\ensuremath{\Gamma}({D}^{+}\ensuremath{\rightarrow}{\overline{K}}^{0}{\ensuremath{\pi}}^{+})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}(19.96\ifmmode\pm\else\textpm\fi{}1.19\ifmmode\pm\else\textpm\fi{}0.96)%$.
24 citations
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, University of Illinois at Urbana–Champaign5, Indiana University6, Korea University7, Kyungpook National University8, University of Milan9, University of North Carolina at Asheville10, University of Puerto Rico at Mayagüez11, University of South Carolina12, University of Tennessee13, Vanderbilt University14, University of Wisconsin-Madison15
TL;DR: The first clear observation of the doubly Cabibbo suppressed decay D+→K−K+K+ K+ and the first observation of singly CCSD Ds+→ K−K + K+K+. These signals were obtained by analyzing the high statistics sample of photoproduced charm particles of the FOCUS (E831) experiment at Fermilab.
13 citations
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, University of Illinois at Urbana–Champaign5, Indiana University6, Korea University7, University of Milan8, University of North Carolina at Chapel Hill9, University of Puerto Rico at Mayagüez10, University of South Carolina11, University of Tennessee12, Vanderbilt University13, University of Wisconsin-Madison14
TL;DR: A high statistics measurement of the lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented in this paper, with particular attention to the determination of the systematic uncertainty.
Abstract: A high statistics measurement of the ${\ensuremath{\Lambda}}_{c}^{+}$ lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. We describe the analysis technique with particular attention to the determination of the systematic uncertainty. The measured value of $204.6\ifmmode\pm\else\textpm\fi{}3.4(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}2.5(\mathrm{syst})\mathrm{fs}$ from $8034\ifmmode\pm\else\textpm\fi{}122{\ensuremath{\Lambda}}_{c}^{+}\ensuremath{\rightarrow}{\mathrm{pK}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$ decays represents a significant improvement over the present world average.
12 citations
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, University of Illinois at Urbana–Champaign5, Indiana University6, Korea University7, Kyungpook National University8, University of Milan9, University of North Carolina at Chapel Hill10, University of Puerto Rico at Mayagüez11, University of South Carolina12, University of Tennessee13, Vanderbilt University14, University of Wisconsin-Madison15
TL;DR: In this article, the existence of diffractively photoproduced enhancement in K+K− at 1750 MeV/c2 with nearly 100 times the statistics of previous experiments was confirmed.
12 citations
10 citations
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, University of Illinois at Urbana–Champaign5, Indiana University6, Korea University7, Kyungpook National University8, University of Milan9, University of North Carolina at Chapel Hill10, University of Puerto Rico at Mayagüez11, University of South Carolina12, University of Tennessee13, Vanderbilt University14, University of Wisconsin-Madison15
TL;DR: In this paper, the authors measured the lifetime of the charmed baryon Ξco using the decay channels Ξ co→Ξ−π+ and Ξ c o →Ω − K +.
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, University of Illinois at Urbana–Champaign5, Indiana University6, Korea University7, Kyungpook National University8, University of Milan9, University of North Carolina at Chapel Hill10, University of Puerto Rico at Mayagüez11, University of South Carolina12, University of Tennessee13, Vanderbilt University14, University of Wisconsin-Madison15
TL;DR: In this article, the authors studied the Cabibbo suppressed decay Λ c + → Σ + K *0 (892) and the CSA favored decays and measured their branching ratios.
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, University of Wisconsin-Madison4, Fermilab5, University of Illinois at Urbana–Champaign6, Indiana University7, Korea University8, Kyungpook National University9, University of Milan10, University of North Carolina at Chapel Hill11, University of Puerto Rico at Mayagüez12, University of South Carolina13, University of Tennessee14, Vanderbilt University15
TL;DR: In this paper, the authors used a large sample of charm semileptonic decays collected by the FOCUS photoproduction experiment at Fermilab to obtain new measurements of two semi-ptonic branching ratios.
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, University of Illinois at Urbana–Champaign5, Indiana University6, Korea University7, University of Milan8, University of North Carolina at Asheville9, University of Puerto Rico at Mayagüez10, University of South Carolina11, University of Tennessee12, Vanderbilt University13, University of Wisconsin-Madison14
TL;DR: In this article, the authors present a measurement of the natural widths of Σ c 0 and ǫ c ++ using data from the FOCUS experiment, and they find Γ ( Σc 0 )=1.55 + 0.41 −0.37 ± 0.38
Journal Article•
Journal Article•
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, University of Illinois at Urbana–Champaign5, Indiana University6, Korea University7, University of Milan8, University of North Carolina at Chapel Hill9, University of Puerto Rico at Mayagüez10, University of South Carolina11, University of Tennessee12, Vanderbilt University13, University of Wisconsin-Madison14
TL;DR: In this article, a high-statistics sample of photoproduced charm from the FOCUS experiment has been used to search for direct CP violation in the decay rates for D → K S π + and D + → KS K +.
Abstract: A high-statistics sample of photoproduced charm from the FOCUS experiment has been used to search for direct CP violation in the decay rates for D → K S π + and D + → K S K + . We have measured the following asymmetry parameters relative to D + → K - π + π + : A C P (K S π + ) = (-1.6 ′ 1.5 ′ 0.9)%, A C P (K S K + ) = (+6.9 ′ 6.0 ′ 1.5)%, and A C P (K S K + ) = (+7.1 ′ 6.1 ′ 1.2)% relative to D + → K S π + . We have also measured the relative branching ratios and found Γ(D + + K 0 π + )/Γ(D + → K π + π + ) = (30.60 ′ 0.46 ′ 0.32)%, Γ(D + → K 0 K + )/Γ(D + → K - π + π + ) = (6.04 ′ 0.35 ′ 0.30)%, and Γ(D + → K 0 K + )/Γ(D + → K 0 π + ) = (19.96 ′ 1.19 ′ 0.96)%.