34 research outputs found
A measurement of lifetime differences in the neutral D-meson system
Using a high statistics sample of photoproduced charm particles from the
FOCUS experiment at Fermilab, we compare the lifetimes of neutral D mesons
decaying via D0 to K- pi+ and K- K+ to measure the lifetime differences between
CP even and CP odd final states. These measurements bear on the phenomenology
of D0 - D0bar mixing. If the D0 to K-pi+ is an equal mixture of CP even and CP
odd eigenstates, we measure yCP = 0.0342 \pm 0.0139 \pm 0.0074.Comment: 15 pages, 5 figure
Search for CP violation in D0 and D+ decays
A high statistics sample of photoproduced charm particles from the FOCUS
(E831) experiment at Fermilab has been used to search for CP violation in the
Cabibbo suppressed decay modes D+ to K-K+pi+, D0 to K-K+ and D0 to pi-pi+. We
have measured the following CP asymmetry parameters: A_CP(K-K+pi+) = +0.006 +/-
0.011 +/- 0.005, A_CP(K-K+) = -0.001 +/- 0.022 +/- 0.015 and A_CP(pi-pi+) =
+0.048 +/- 0.039 +/- 0.025 where the first error is statistical and the second
error is systematic. These asymmetries are consistent with zero with smaller
errors than previous measurements.Comment: 12 pages, 4 figure
Measurements of the Sigma_c^0 and Sigma_c^{++} Mass Splittings
Using a high statistics sample of photoproduced charmed particles from the
FOCUS experiment at Fermilab (FNAL-E831), we measure the mass splittings of the
charmed baryons Sigma_c^0 and Sigma_c^{++}. We find M(Sigma_c^0 - Lambda_c^+) =
167.38 +/- 0.21 +/- 0.13 MeV/c^2 and M(Sigma_c^++ - Lambda_c^+) = 167.35 +/-
0.19 +/- 0.12 MeV/c^2 with samples of 362 +/- 36 and 461 +/- 39 events,
respectively. We measure the isospin mass splitting M(Sigma_c^++ - Sigma_c^0)
to be -0.03 +/- 0.28 +/- 0.11 Mev/c^2. The first errors are statistical and the
second are systematic.Comment: 10 pages, 2 figure
Evidence for a narrow dip structure at 1.9 GeV/c in diffractive photoproduction
A narrow dip structure has been observed at 1.9 GeV/c in a study of
diffractive photoproduction of the final state performed by the
Fermilab experiment E687.Comment: The data of Figure 6 can be obtained by downloading the raw data file
e687_6pi.txt. v5 (2nov2018): added Fig. 7, the 6 pion energy distribution as
requested by a reade
Ultimate pit limit determination for semi mobile in-pit crushing and conveying system: a case study
Semi mobile in-pit crushing and conveying systems have different pit shape requirements to traditional truck haulage systems due to the inclusion of a conveyor flight in the pit. As the shape of a pit is heavily influenced by the ultimate pit limit, it is desirable to have the additional shape requirements included in the ultimate pit limit determination process. This paper introduces in-pit crushing and conveying systems and discusses their differences and benefits. The differences and requirements of pit design between truck haulage and semi mobile in-pit crushing and conveying systems are then highlighted. A method of including the additional requirements during the ultimate pit limit determination is presented. A case study has been included that shows the method working successfully, with scheduling of the pits to further highlight semi mobile in-pit crushing and conveying viability. This case study shows that through the reduced mining costs, a semi mobile in-pit crushing and conveying pit can return a higher Net Present Value, despite being smaller than the traditional truck and shovel pit for the same deposit. The development of this method provides the opportunity for the metalliferous industry to accurately determine ultimate pit limits for a mines considering the use of semi mobile in-pit crushing and conveying systems
Palaeobotanical evidence for warm summers in the East Siberian Arctic during the last cold stage
Plant macrofossils from the Mamontovy Khayata permafrost sequence (71°60N, 129°25E) on the Bykovsky Peninsula reflect climate and plant biodiversity in west Beringia during the last cold stage. 70 AMS and 20 conventional 14C dates suggest sediment accumulation between about 60,000 and 7500 14C yr B.P. The plant remains prove that during the last cold stage arctic species (Minuartia arctica, Draba spp., Kobresia myosuroides) coexisted with aquatic (Potamogeton vaginatus, Callitriche hermaphroditica), littoral (Ranunculus reptans, Rumex maritimus), meadow (Hordeum brevisubulatum, Puccinellia tenuiflora) and steppe taxa (Alyssum obovatum, Silene repens, Koeleria cristata, Linum perenne). The reconstructed vegetation composition is similar to modern vegetation mosaics in central and northeast Yakutian relict steppe areas. Thus, productive meadow and steppe communities played an important role in the Siberian Arctic vegetation during the late Pleistocene, and could have served as food resource for large populations of herbivores. The floristic composition reflects an extremely continental, arid climate with winters colder and summers distinctly warmer than at present. Holocene macrofossil assemblages indicate a successive paludification possibly connected with marine transgression, increased oceanic influence, and atmospheric humidity. Although some steppe taxa were still present in the early Holocene, they disappeared completely before ~2900 14C yr B.P
Visual Color Deterioration in Blackcurrant Syrup Predicted by Different Instrumental Variables
Search for the decay of D+ and Ds+ mesons to three charged kaons
We report the results of a search for the doubly Cabibbo suppressed decays D+ \u2192 K+K 12K+ and D+ \u2192 phi K+, and the singly Cabibbo suppressed decays Ds+ \u2192 K+K 12K+ and Ds+ \u2192 phi K+. Our measurements are all consistent with zero branching ratio, and we set 90% confidence level upper limits on the relative D+ branching ratios: BR(phi K+)/BR(phi pi+) < 0.021, BR(K+K-K+)/BR(phi pi+) < 0.025, and BR(K+K-K+)/BR(K-pi+pi+) < 0.0016, and the relative Ds+ branching ratios: BR(phi K+) / BR(phi pi+) < 0.013 and BR(K+K-K+)/BR(phi pi+) < 0.016. 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
Charged hadronic five-body decays of D+ and Ds+ mesons have been studied in the E687 photoproduction experiment at Fermilab. We report the first compelling evidence of the decay mode D+, Ds+ \u2192 pi 12pi 12pi+pi+pi+ and the measurements of the decays D+ \u2192 K 12pi 12pi+pi+pi+, Ds+ \u2192 K 12K+pi 12pi+pi+ and Ds+ \u2192 phi pi 12pi+pi+. An analysis of the D+ \u2192 K 12pi 12pi+pi+pi+ resonance structure is also presente