19 research outputs found
Soft end-point and mass corrections to the eta' g*g* vertex function
Power-suppressed corrections arising from end-point integration regions to
the space-like vertex function of the massive eta'-meson virtual gluon
transition eta' - g*g* are computed. Calculations are performed within the
standard hard-scattering approach (HSA) and the running coupling method
supplemented by the infrared renormalon calculus. Contributions to the vertex
function from the quark and gluon contents of the eta' -meson are taken into
account and the Borel resummed expressions for F_{eta' g*g*}(Q2,\omega ,\eta),
as well as for F_{eta' g g*}}(Q^{2},\omega =\pm 1,\eta) and F_{eta'
g*g*}(Q^{2},\omega =0,\eta) are obtained. It is demonstrated that the
power-suppressed corrections \sim (\Lambda ^{2}/Q^{2})^{n}, in the explored
range of the total gluon virtuality 1 <Q2 < 25 GeV2, considerably enhance the
vertex function relative to the results found in the framework of the standard
HSA with a fixed coupling. Modifications generated by the eta ' -meson mass
effects are discussed
The B^- -> phi phi K^- decay rate with phi phi invariant mass below charm treshold
We investigate the decay mechanism in the B^- -> phi phi K^- decay with the
phi phi invariant mass below the charm threshold and in the neighborhood of the
eta_c invariant mass region. Our approach is based on the use of factorization
model and the knowledge of matrix elements of the weak currents. For the B
meson weak transition we apply form factor formalism, while for the light
mesons we use effective weak and strong Lagrangians. We find that the dominant
contributions to the branching ratio come from the eta, eta' and eta(1490) pole
terms of the penguin operators in the decay chains B^- -> eta (eta', eta(1490))
K^- -> phi phi K^-. Our prediction for the branching ratio is in agreement with
the Belle's result.Comment: 14 pages, 4 figures, 2 table
Population, Land Use and Deforestation in the Pan Amazon Basin: a Comparison of Brazil, Bolivia, Colombia, Ecuador, Perú and Venezuela
This paper discusses the linkages between population change, land use, and deforestation in the Amazon regions of Brazil, Bolivia, Colombia, Ecuador, Perú, and Venezuela. We begin with a brief discussion of theories of population–environment linkages, and then focus on the case of deforestation in the PanAmazon. The core of the paper reviews available data on deforestation, population growth, migration and land use in order to see how well land cover change reflects demographic and agricultural change. The data indicate that population dynamics and net migration exhibit to deforestation in some states of the basin but not others. We then discuss other explanatory factors for deforestation, and find a close correspondence between land use and deforestation, which suggests that land use is loosely tied to demographic dynamics and mediates the influence of population on deforestation. We also consider national political economic contexts of Amazon change in the six countries, and find contrasting contexts, which also helps to explain the limited demographic-deforestation correspondence. The paper closes by noting general conclusions based on the data, topics in need of further research and recent policy proposals.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42720/1/10668_2003_Article_6977.pd