2,226 research outputs found
Révision des espèces de Cladochonus McCoy, 1847 (Tabulata) décrites dans le Frasnien de la Belgique par LECOMPTE en 1939 - Cladochonus frasniens de Belgique
The original material of the three species from the Frasnian of Belgium formerly assigned to the genus Cladochonus McCoy, 1847 by LECOMPTE (1939) has been revised. Two of these species are considered valid and maintained in the genus: C. robustus LECOMPTE, 1939 and C. maillieuxi LECOMPTE, 1939; C. brevicollis devonicus is for us a synonym of the last species. A microstructural study of C. robustus affords a useful comparison with the microstructure of typical Cladochonus from the Carboniferous. A systematical hierarchy of characters is proposed for the family Pyrgiidae DE FROMENTEL, 1861
Sedimentologie et coraux du bioherme de marbre rouge Frasnien (F2j) de Tapoumont (Massif de Phillippeville, Belgique)
The sedimentological study of the Frasnian Tapoumont red marble bioherm (Philippeville antiform, Belgium, «F2j» based on rugose corals) enables recognition of twelve microfacies. They range from sponge spicule mudstones to crinoidal, coral rudstones. Water agitation and light supply normally control the bioherm growth, but three environments do not follow the rule. They are characterized by the abundance of microorganic mats, now in form of irregular plurimetric fenestrae. cemented by radiaxial calcite. They are more and more abundant towards the centre of the buildup. Four lateral microfacies are studied. The bioherm geometry is discussed, and a weak sedimentary slope is proposed
Sedimentologie paleoecologie et paleontologie des calcaires crinoidiques au voisinage de la limite couvinien-givetien a Wellin
The sedimentology of the Eifelian-Givetian boundary beds in the Wellin area indicates a transition from a siliciclastic-carbonate ramp to a gently sloping carbonate platform lacking a true reefal barrier. Prograding decametric sedimentary units form a littoral accretion megasequence. Corallian megafauna and algal microflora are highly diverse and abundant. Several communities are recognized in the ramp but they cannot be used for precise chronostratigraphic correlations.Comparison with other regions of the Dinant Synclinorium shows that the basin was already partitioned into blocks in Late Eifelian time. In Early Givetian several blocks of plurikilometric extension are identified. In this context, recognition of a new formation, provisionnally called "Formation X", between the Jemelle and Hanonet Formations, is significant.This local unit, some 120 meters thick, is composed of crinoidal and reefal limestones and indicates the existence of a sharply subsiding block in the Wellin area
Microstructure du genre Favosites Lamarck 1816 (Tabulata) et de <i>Favositides</i> du Silurien, avec une revision du Neotype de <i>Favosites Gothlandicus</i> Lamarck 1816
The Neotype of Favosites gothlandicus Lamarck 1816, the type species of the genus Favosites Lamarck 1816, is redescribed in detail. Its walls are composed of microlamellae flanking a median plate made of plaquettes. This typical microstructure also occurs in numerous Silurian species of Favosites and Paleofavosites Twenhofel 1914. Diagnoses of these two genera are consequently emendated to include these microstructural details
New data on the Silurian-Devonian paleontology and biostratigraphy of Bolivia
P. 269-314In order to precisely establish the bio- and chronostratigraphic position of several levels of the Silurian–Devonian succession
of Bolivia, with respect to the International Time Scale, additional Silurian and Devonian localities belonging to
the Eastern Cordillera and the Interandean Zone areas have been recently revised and sampled, both for macrofossils and
palynomorphs. Specifically, the localities are Ñuñumayani, and Muruhuta from the late Silurian–early Devonian time
interval. Correlations with other fossiliferous localities are discussed, namely Huacallani and Rumicorral.S
Measurement of the ratio of branching fractions BR(B0 -> K*0 gamma)/BR(Bs0 -> phi gamma)
The ratio of branching fractions of the radiative B decays B0 -> K*0 gamma
and Bs0 -> phi gamma has been measured using 0.37 fb-1 of pp collisions at a
centre of mass energy of sqrt(s) = 7 TeV, collected by the LHCb experiment. The
value obtained is BR(B0 -> K*0 gamma)/BR(Bs0 -> phi gamma) = 1.12 +/- 0.08
^{+0.06}_{-0.04} ^{+0.09}_{-0.08}, where the first uncertainty is statistical,
the second systematic and the third is associated to the ratio of fragmentation
fractions fs/fd. Using the world average for BR(B0 -> K*0 gamma) = (4.33 +/-
0.15) x 10^{-5}, the branching fraction BR(Bs0 -> phi gamma) is measured to be
(3.9 +/- 0.5) x 10^{-5}, which is the most precise measurement to date.Comment: 15 pages, 1 figure, 2 table
Opposite-side flavour tagging of B mesons at the LHCb experiment
The calibration and performance of the oppositeside
flavour tagging algorithms used for the measurements
of time-dependent asymmetries at the LHCb experiment
are described. The algorithms have been developed using
simulated events and optimized and calibrated with
B
+ →J/ψK
+, B0 →J/ψK
∗0 and B0 →D
∗−
μ
+
νμ decay
modes with 0.37 fb−1 of data collected in pp collisions
at
√
s = 7 TeV during the 2011 physics run. The oppositeside
tagging power is determined in the B
+ → J/ψK
+
channel to be (2.10 ± 0.08 ± 0.24) %, where the first uncertainty
is statistical and the second is systematic
Differential branching fraction and angular analysis of the decay B0→K∗0μ+μ−
The angular distribution and differential branching fraction of the decay B 0→ K ∗0 μ + μ − are studied using a data sample, collected by the LHCb experiment in pp collisions at s√=7 TeV, corresponding to an integrated luminosity of 1.0 fb−1. Several angular observables are measured in bins of the dimuon invariant mass squared, q 2. A first measurement of the zero-crossing point of the forward-backward asymmetry of the dimuon system is also presented. The zero-crossing point is measured to be q20=4.9±0.9GeV2/c4 , where the uncertainty is the sum of statistical and systematic uncertainties. The results are consistent with the Standard Model predictions
Observation of two new baryon resonances
Two structures are observed close to the kinematic threshold in the mass spectrum in a sample of proton-proton collision data, corresponding
to an integrated luminosity of 3.0 fb recorded by the LHCb experiment.
In the quark model, two baryonic resonances with quark content are
expected in this mass region: the spin-parity and
states, denoted and .
Interpreting the structures as these resonances, we measure the mass
differences and the width of the heavier state to be
MeV,
MeV,
MeV, where the first and second
uncertainties are statistical and systematic, respectively. The width of the
lighter state is consistent with zero, and we place an upper limit of
MeV at 95% confidence level. Relative
production rates of these states are also reported.Comment: 17 pages, 2 figure
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