2,897 research outputs found
Ultrahigh energy neutrino scattering: an update
We update our estimates of charged and neutral current neutrino total cross
sections on isoscalar nucleons at ultrahigh energies using a global (x, Q^2)
fit, motivated by the Froissart bound, to the F_2 (electron-proton) structure
function utilizing the most recent analysis of the complete ZEUS and H1 data
sets from HERA I. Using the large Q^2, small Bjorken-x limits of the "wee"
parton model, we connect the ultrahigh energy neutrino cross sections directly
to the large Q^2, small-x extrapolation of our new fit, which we assume
saturates the Froissart bound. We compare both to our previous work, which
utilized only the smaller ZEUS data set, as well as to recent results of a
calculation using the ZEUS-S based global perturbative QCD parton distributions
using the combined HERA I results as input. Our new results substantiate our
previous conclusions, again predicting significantly smaller cross sections
than those predicted by extrapolating pQCD calculations to neutrino energies
above 10^9 GeV.Comment: 8 pages, 1 figure, 3 table
Anveshak - A Groundtruth Generation Tool for Foreground Regions of Document Images
We propose a graphical user interface based groundtruth generation tool in
this paper. Here, annotation of an input document image is done based on the
foreground pixels. Foreground pixels are grouped together with user interaction
to form labeling units. These units are then labeled by the user with the user
defined labels. The output produced by the tool is an image with an XML file
containing its metadata information. This annotated data can be further used in
different applications of document image analysis.Comment: Accepted in DAR 201
Decoupling the coupled DGLAP evolution equations: an analytic solution to pQCD
Using Laplace transform techniques, along with newly-developed accurate
numerical inverse Laplace transform algorithms, we decouple the solutions for
the singlet structure function and of the two
leading-order coupled singlet DGLAP equations, allowing us to write fully
decoupled solutions: F_s(x,Q^2)={\cal F}_s(F_{s0}(x), G_0(x)), G(x,Q^2)={\cal
G}(F_{s0}(x), G_0(x)). Here and are known
functions---found using the DGLAP splitting functions---of the functions
and , the chosen
starting functions at the virtuality . As a proof of method, we compare
our numerical results from the above equations with the published MSTW LO gluon
and singlet distributions, starting from their initial values at . Our method completely decouples the two LO distributions, at the same
time guaranteeing that both distributions satisfy the singlet coupled DGLAP
equations. It furnishes us with a new tool for readily obtaining the effects of
the starting functions (independently) on the gluon and singlet structure
functions, as functions of both and . In addition, it can also be
used for non-singlet distributions, thus allowing one to solve analytically for
individual quark and gluon distributions values at a given and , with
typical numerical accuracies of about 1 part in , rather than having to
evolve numerically coupled integral-differential equations on a two-dimensional
grid in , as is currently done.Comment: 6 pages, 2 figure
Multidimensional Calogero systems from matrix models
We show that a particular many-matrix model gives rise, upon hamiltonian
reduction, to a multidimensional version of the Calogero-Sutherland model and
its spin generalizations. Some simple solutions of these models are
demonstrated by solving the corresponding matrix equations. A connection of
this model to the dimensional reduction of Yang-Mills theories to
(0+1)-dimensions is pointed out. In particular, it is shown that the low-energy
dynamics of D0-branes in sectors with nontrivial fermion content is that of
spin-Calogero particles.Comment: 12 pages, no figures, plain tex, phyzzx macr
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