1,286 research outputs found
Predicitions for high-energy real and virtual photon-photon scattering from color dipole BFKL-Regge factorization
High-energy virtual photon-virtual photon scattering can be viewed as
interaction of small size color dipoles from the beam and target photons, which
makes scattering at high energies
(LEP, LEP200 & NLC) an indispensable probe of short distance properties of the
QCD pomeron exchange. Based on the color dipole representation, we investigate
consequences for the scattering of the
incorporation of asymptotic freedom into the BFKL equation which makes the QCD
pomeron a series of isolated poles in the angular momentum plane. The emerging
color dipole BFKL-Regge factorization allows us to relate in a
model-independent way the contributions of each BFKL pole to
scattering and DIS off protons.
Numerical predictions based on our early works on color dipole BFKL
phenomenology of DIS on protons are in a good agreement with the experimental
data on the photon structure function and most recent data on the
cross section from OPAL and
L3 experiments at LEP200.
We discuss the role of non-perturbative dynamics and predict pronounced
effect of the Regge-factorization breaking due to large unfactorizable
non-perturbative corrections to the perturbative vacuum exchange. We comment on
the salient features of the BFKL-Regge expansion for
scattering including the issue of
decoupling of subleading BFKL poles and the soft plus rightmost hard BFKL pole
dominance .Comment: 16 pages, 10 figures; treatment of the soft component is modified,
one more figure with the description of the recent data from OPAL is added.
The version to appear in Eur. Phys. J.
ASM-Clust: classifying functionally diverse protein families using alignment score matrices
Rapid advances in sequencing technology have resulted in the availability of genomes from organisms across the tree of life. Accurately interpreting the function of proteins in these genomes is a major challenge, as annotation transfer based on homology frequently results in misannotation and error propagation. This challenge is especially pressing for organisms whose genomes are directly obtained from environmental samples, as interpretation of their physiology and ecology is often based solely on the genome sequence. For complex protein (super)families containing a large number of sequences, classification can be used to determine whether annotation transfer is appropriate, or whether experimental evidence for function is lacking. Here we present a novel computational approach for de novo classification of large protein (super)families, based on clustering an alignment score matrix obtained by aligning all sequences in the family to a small subset of the data. We evaluate our approach on the enolase family in the Structure Function Linkage Database
Incoherent Eta Photoproduction from the Deuteron near Threshold
Very recent data for the reaction gamma+d ->eta np, namely total cross
sections, angular and momentum spectra, are analyzed within a model that
includes contributions from the impulse approximation and next order
corrections due to the np and eta-N interactions in the final state. Comparison
between the calculations and the new data indicate sizable contributions from
the np and eta-N final state interactions. Some systematic discrepancies
between the calculations and the data are also found
A microscopic investigation of the transition form factor in the region of collective multipole excitations of stable and unstable nuclei
We have used a self-consistent Skyrme-Hartree-Fock plus Continuum-RPA model
to study the low-multipole response of stable and neutron/proton-rich Ni and Sn
isotopes. We focus on the momentum-transfer dependence of the strength
distribution, as it provides information on the structure of excited nuclear
states and in particular on the variations of the transition form factor (TFF)
with the energy. Our results show, among other things, that the TFF may show
significant energy dependence in the region of the isoscalar giant monopole
resonance and that the TFF corresponding to the threshold strength in the case
of neutron-rich nuclei is different compared to the one corresponding to the
respective giant resonance. Perspectives are given for more detailed future
investigations.Comment: 13 pages, incl. 9 figures; to appear in J.Phys.G,
http://www.iop.org/EJ/jphys
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