16 research outputs found
A first estimate of triply heavy baryon masses from the pNRQCD perturbative static potential
Within pNRQCD we compute the masses of spin-averaged triply heavy baryons
using the now-available NNLO pNRQCD potentials and three-body variational
approach. We focus in particular on the role of the purely three-body
interaction in perturbation theory. This we find to be reasonably small and of
the order 25 MeV Our prediction for the Omega_ccc baryon mass is 4900(250) in
keeping with other approaches. We propose to search for this hitherto
unobserved state at B factories by examining the end point of the recoil
spectrum against triple charm.Comment: 18 figures, 21 page
Nucleon resonances in the fourth resonance region
Nucleon and resonances in the fourth resonance region are studied in
a multichannel partial-wave analysis which includes nearly all available data
on pion- and photo-induced reactions off protons. In the high-mass range, above
1850\,MeV, several alternative solutions yield a good description of the data.
For these solutions, masses, widths, pole residues and photo-couplings are
given. In particular, we find evidence for nucleon resonances with
spin-parities . For one set of solutions, there are four
resonances forming naturally a spin-quartet of resonances with orbital angular
momentum L=2 and spin S=3/2 coupling to . Just below 1.9\,GeV we
find a spin doublet of resonances with and . Since a spin
partner with is missing at this mass, the two resonances form a
spin doublet which must have a symmetric orbital-angular-momentum wave function
with L=1. For another set of solutions, the four positive-parity resonances are
accompanied by mass-degenerate negative-parity partners -- as suggested by the
conjecture of chiral symmetry restoration. The possibility of a spin doublet at 1900\,MeV belonging to a 20-plet is discussed.Comment: 16 page
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Gyrotron: an ECH system component
The gyrotron, or electron-cyclotron maser, in the form of a gyromonotron, is being developed as a source of millimeter wave energy for fusion plasma heating. The characteristics of this high power, high efficiency electron tube are described in terms of the requirements for the beam power supply system, the mechanical support system, the cooling system, the focusing and tuning magnets, and the waveguide system. Requirements of power level and transmission efficiency dictate the use of oversize waveguide. The implications, both to the user and to the interaction mechanisms in the gyrotron, of the use of oversize waveguide are treated. The effects of variations of various operating parameters upon the gyrotron's power output and stability are also discussed. Data from gyrotron development and system operation are used where appropriate
Trace metals in sediments from the humber estuary: A statistical analysis of spatial uniformity
Comparação das comunidades de Entomobryidae e Isotomidae (Collembola) entre plantio direto em três níveis de fertilidade, plantio convencional e um ecossistema natural (campo nativo) em Ponta Grossa, Paraná, Brasil
Aspects toxiques du cuivre sur la biomasse et la productivit� du phytoplancton de la rivi�re du Saguenay, Qu�bec
The impact of altered precipitation on spatial stratification and activity-densities of springtails (Collembola) and spiders (Araneae)
Relativistic quark-diquark model of baryons with a spin-isospin transition interaction: Non-strange baryon spectrum and nucleon magnetic moments
The relativistic interacting quark-diquark model of baryons, recently developed, is here extended introducing in the mass operator a spin-isospin transition interaction. This refined version of the model is used to calculate the non-strange baryon spectrum. The results are compared to the present experimental data. A preliminary calculation of the magnetic moments of the proton and neutron is also presented