701 research outputs found
Dvofotonski raspad b i d mezona u modelu prevladavajuÄih polova
We give a detailed study of the two-gamma decay of some heavy pseudoscalar mesons using the pole-dominance model. The transition matrix elements of PL to bare glueball (G0) are also computed, and it is found that the PL to glueball contribution is comparable with that of PL to Ļ0. From our results, we have obtained the two-gamma decay width of DL and an upper limit of the two-gamma decay widths of BL and BsL mesons.Podrobno se prouÄavaju dvofotonski raspadi teÅ”kih pseudoskalarnih mezona na osnovi modela prevladavajuÄih polova. IzraÄunavaju se matriÄni elementi prijelaza PL u golu gluonsku loptu (G0 ) i nalazi da je doprinos tog procesa usporediv s doprinosom prijelaza PL u Ļ 0 . IzraÄunate su Å”irina dvofotonskog raspada mezona DL i gornje granice Å”irina dvofotonskih raspada BL i BsL mezona
Konstanta vezanja B-mezon ā kvark i Å”irina raspada Bā-mezona
The pion - quark coupling constant (gĻq q) and the B-meson - quark coupling constant (gB-qq) have been found in the processes B*- ā B-Ļ0 and B*- ā B-Ī³. Their decay widths have been calculated through the direct coupling of Ļ0 and B- with quarks which are static inside B*- meson.OdreÄuju se konstante vezanja pion ā kvark (gĻqq) i B-mezon ā kvark (gBāqq) u procesima BāāāBāĻ0 i BāāāBāĪ³. Njihove se Å”irine raspada raÄunaju preko izravnog vezanja Ļ0 i Bā s kvarkovima koji miruju u Bāā mezonu
Routh's procedure for non-Abelian symmetry groups
We extend Routh's reduction procedure to an arbitrary Lagrangian system (that
is, one whose Lagrangian is not necessarily the difference of kinetic and
potential energies) with a symmetry group which is not necessarily Abelian. To
do so we analyse the restriction of the Euler-Lagrange field to a level set of
momentum in velocity phase space. We present a new method of analysis based on
the use of quasi-velocities. We discuss the reconstruction of solutions of the
full Euler-Lagrange equations from those of the reduced equations.Comment: 30 pages, to appear in J Math Phy
Circular Orbits in Einstein-Gauss-Bonnet Gravity
The stability under radial and vertical perturbations of circular orbits
associated to particles orbiting a spherically symmetric center of attraction
is study in the context of the n-dimensional: Newtonian theory of gravitation,
Einstein's general relativity, and Einstein-Gauss-Bonnet theory of gravitation.
The presence of a cosmological constant is also considered. We find that this
constant as well as the Gauss-Bonnet coupling constant are crucial to have
stability for .Comment: 11 pages, 4 figs, RevTex, Phys. Rev. D, in pres
Lipopolysaccharide (LPS) and tumor necrosis factor alpha (TNF[alfa]) blunt the response of Neuropeptide Y/Agouti-related peptide (NPY/AgRP) glucose inhibited (GI) neurons to decreased glucose
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