519 research outputs found
Deeply Virtual Pseudoscalar Meson Production with CLAS
Deeply virtual meson scattering cross sections and asymmetries for the pi^0
and eta exclusive electroproduction in a very wide kinematic range of Q^2, t
and x_B have been measured with CLAS (JLab). Initial analysis is already
showing remarkable results. These data will help us to better understand the
transition from soft to hard mechanisms.Comment: Prepared for XII Workshop on High Energy Spin Physics DSPIN-07,
Dubna, September 3-7, 200
Lambda(1520,3/2^-) photoproduction reaction via gamma N -> K Lambda(1520)
We investigate Lambda(1520,3/2^-,D_03) photoproduction via the gamma N -> K
Lambda^* reaction process. Using effective Lagrangians, we compute the total
and differential cross sections as well as the dependence on the momentum
transfer for the photoproduction at the tree-level. We employ two different
form factors: The four-dimensional gauge-invariant type and the three
dimensional one depending on the external momenta. We find that the total cross
sections for the proton target are well reproduced as compared with the
experimental data. It turns out that the total cross sections for the neutron
target are significantly smaller than those for the proton target. We also
compare the present results with the gamma N -> bar{K} Theta^+ reaction in
order to extract information of Theta^+. Finally the role of K^*--exchange in
the production reaction is discussed.Comment: 16 pages, 31 figure
Test of the CLAS12 RICH large scale prototype in the direct proximity focusing configuration
A large area ring-imaging Cherenkov detector has been designed to provide
clean hadron identification capability in the momentum range from 3 GeV/c up to
8 GeV/c for the CLAS12 experiments at the upgraded 12 GeV continuous electron
beam accelerator facility of Jefferson Laboratory. The adopted solution
foresees a novel hybrid optics design based on aerogel radiator, composite
mirrors and high-packed and high-segmented photon detectors. Cherenkov light
will either be imaged directly (forward tracks) or after two mirror reflections
(large angle tracks). We report here the results of the tests of a large scale
prototype of the RICH detector performed with the hadron beam of the CERN T9
experimental hall for the direct detection configuration. The tests
demonstrated that the proposed design provides the required pion-to-kaon
rejection factor of 1:500 in the whole momentum range.Comment: 15 pages, 23 figures, to appear on EPJ
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