11 research outputs found
A Bayesian analysis of pentaquark signals from CLAS data
We examine the results of two measurements by the CLAS collaboration, one of
which claimed evidence for a pentaquark, whilst the other found no
such evidence. The unique feature of these two experiments was that they were
performed with the same experimental setup. Using a Bayesian analysis we find
that the results of the two experiments are in fact compatible with each other,
but that the first measurement did not contain sufficient information to
determine unambiguously the existence of a . Further, we suggest a
means by which the existence of a new candidate particle can be tested in a
rigorous manner.Comment: 5 pages, 3 figure
First measurement of direct photoproduction on the proton
We report on the results of the first measurement of exclusive
meson photoproduction on protons for GeV and GeV. Data were collected with the CLAS detector at the Thomas
Jefferson National Accelerator Facility. The resonance was detected via its
decay in the channel by performing a partial wave analysis of the
reaction . Clear evidence of the meson
was found in the interference between and waves at GeV. The -wave differential cross section integrated in the mass range of
the was found to be a factor of 50 smaller than the cross section
for the meson. This is the first time the meson has been
measured in a photoproduction experiment
Deeply Virtual Compton Scattering Beam-Spin Asymmetries
The beam spin asymmetries in the hard exclusive electroproduction of photons
on the proton (ep -> epg) were measured over a wide kinematic range and with
high statistical accuracy. These asymmetries result from the interference of
the Bethe-Heitler process and of deeply virtual Compton scattering. Over the
whole kinematic range (x_B from 0.11 to 0.58, Q^2 from 1 to 4.8 GeV^2, -t from
0.09 to 1.8 GeV^2), the azimuthal dependence of the asymmetries is compatible
with expectations from leading-twist dominance, A = a*sin(phi)/[1+c*cos(phi)].
This extensive set of data can thus be used to constrain significantly the
generalized parton distributions of the nucleon in the valence quark sector.Comment: 1 tex file (6 pages), 4 (eps) figure
Three-dimensional geological-geophysical lithosphere model of the central part of the Karelian craton
On the base of analysis and generalization of total available geological-geophysical information accumulated during forty years passed a complex of geophysical models of the earth’s crust has been obtained, which gives up-to-date idea on deep structure of the central part of the Karelian craton. The plotted seismic 3D density and magnetic models define more exactly our notions on stratification of the earth’s crust, the behavior of geophysical boundaries including the crust-mantle one. Complex interpretation of potential fields based on seismic model of the earth’s crust of the region taking into account petro-physical and geological data, made possible to estimate special features of layered-blocky structure of the region and of structural correlation of sub-longitudinal suture (the fragment of Ladoga-Pechenga zone of multiple activization) in tectonic division and its relation to deep magnetic sources
Three-dimensional geological-geophysical lithosphere model of the central part of the Karelian craton
On the base of analysis and generalization of total available geological-geophysical information accumulated during forty years passed a complex of geophysical models of the earth’s crust has been obtained, which gives up-to-date idea on deep structure of the central part of the Karelian craton. The plotted seismic 3D density and magnetic models define more exactly our notions on stratification of the earth’s crust, the behavior of geophysical boundaries including the crust-mantle one. Complex interpretation of potential fields based on seismic model of the earth’s crust of the region taking into account petro-physical and geological data, made possible to estimate special features of layered-blocky structure of the region and of structural correlation of sub-longitudinal suture (the fragment of Ladoga-Pechenga zone of multiple activization) in tectonic division and its relation to deep magnetic sources
A seismic section of the upper mantle along the FENNOLORA profile (Baltic Shield) on the basis of the 2D inhomogeneous model of a medium
Gene structure, localization and role in oxidative stress of methionine sulfoxide reductase A (MSRA) in the monkey retina
Elastic-anisotropic properties of garnet granulites from the lower crust of the belomorian mobile belt: Results of experimental study
Measurement of ep->ep beam spin asymmetries above the resonance region
5 pages, 6 figuresThe beam spin asymmetry (BSA) in the exclusive reaction ep->ep pi0 was measured with the CEBAF 5.77 GeV polarized electron beam and Large Acceptance Spectrometer(CLAS). The xB, Q2, t and phi dependences of the pi0 BSA are presented in the deep inelastic regime. The asymmetries are fitted with a sin(phi) function and their amplitudes are extracted. Overall, they are of the order of 0.04 - 0.11 and roughly independent of t. This is the signature of a non-zero longitudinal-transverse interference. The implications concerning the applicability of a formalism based on generalized parton distributions, as well as the extension of a Regge formalism at high photon virtualities, are discussed