7,911 research outputs found
Polarised deep inelastic scattering accompanied by a forward jet as a probe of the resummation
We argue that the production of forward jets in polarised deep inelastic
scattering can be a useful tool for probing the double resummation
effects which control the polarised deep inelastic scattering for small values
of the Bjorken parameter . We solve the corresponding integral equations
generating the double resummation and calculate the differential
structure function describing the forward jet production in the small
regime which can possibly be probed by the polarised HERA measurements. We show
that these structure functions should exhibit the characteristic increase with
decreasing , where denotes the longitudinal momentum fraction of
the parent proton carried by a jet, and we quantify this increase.Comment: 13 pages, latex, 5 figure
QCD predictions for polarised deep inelastic scattering accompanied by a forward jet in the low x region of possible HERA measurements
We estimate the cross-section and asymmetry relevant for the production of
forward jets in polarised deep inelastic scattering in the region of small
values of which can be probed at possible polarised HERA measurements. The
kinematical cuts implemented in our analysis are the same as those which were
used in the unpolarised deep inelastic scattering at HERA. The calculations are
based on the double ln^2(1/x) resummation which controls the polarised deep
inelastic scattering for small values of the Bjorken parameter x. We show that
this resummation substantially enhances the corresponding cross-section and
asymmetry. The predicted value of the asymmetry is found to vary between -0.01
and -0.04 within the small x region which can possibly be probed at polarised
HERA measurements.Comment: 9 pages, latex, 3 figure
Flavor Singlet Contribution to the Structure Function at Small-x
The singlet contribution to the structure function is calculated
in the double-logarithmic approximation of perturbative QCD in the region . Double logarithmic contributions of the type which are not included in the GLAP evolution equations are shown to
give a power-like rise at small-x which is much stronger than the extrapolation
of the GLAP expressions. The dominant contribution is due to the gluons which,
in contrast to the unpolarized case, mix with the fermions also in the region
. The two main reasons why the small-x behavior of the double
logarithmic approximation is so much stronger than the usual GLAP evolution
are: the larger kinematical region of integration (in particular, no ordering
in transverse momentum) and the contributions from non-ladder diagrams.Comment: LaTeX with 9 Figures in a separate file. Full file also available at
http://www.desy.de/ftp/pub/preprints/desy/1996/desy96-025.ps and
http://www.desy.de/ftp/pub/preprints/desy/1996/desy96-025.fig1.p
The Nebraska Marketable Title Act: Another Tool in the Bag
The question in this article is what has and should be done to achieve a more efficient land transfer system. Section II discusses what has been done to remedy the difficulties associated with the transfer of land, and section III focuses on one specific remedy: the Nebraska Marketable Title Act. Section IV contains some recommendations for change and a brief conclusion
The Nebraska Marketable Title Act: Another Tool in the Bag
The question in this article is what has and should be done to achieve a more efficient land transfer system. Section II discusses what has been done to remedy the difficulties associated with the transfer of land, and section III focuses on one specific remedy: the Nebraska Marketable Title Act. Section IV contains some recommendations for change and a brief conclusion
Pomeron-Odderon interference effects in electroproduction of
We review the results of our studies on the charge and the spin asymmetries
in the electroproduction of which are the observables sensitive
to the Pomeron-Odderon interference.Comment: 5 pages LATEX, Talk given by L.Sz. at the 9th Int. High-Energy
Physics Conference QCD '02, Montpellier, France, 2-9th July 200
Spatially resolved in vivo plant metabolomics by laser ablation-based mass spectrometry imaging (MSI) techniques: LDI-MSI and LAESI
This short review aims to summarize the current developments and applications of mass spectrometry-based methods for in situ profiling and imaging of plants with minimal or no sample pre-treatment or manipulation. Infrared-laser ablation electrospray ionization and UV-laser desorption/ionization methods are reviewed. The underlying mechanisms of the ionization techniques–namely, laser ablation of biological samples and electrospray ionization–as well as variations of the LAESI ion source for specific targets of interest are described
Influence of ion source geometry on the repeatability of topographically guided LAESI-MSI
[Image: see text] Spatially resolving the relative distribution of analyte molecules in biological matter holds great promise in the life sciences. Mass spectrometry imaging (MSI) is a technique that can provide such spatial resolution but remains underused in fields such as chemical ecology, as traditional MSI sample preparation is often chemically or morphologically invasive. Laser ablation electrospray ionization (LAESI)-MSI is a variation of MSI particularly well-suited for situations where chemical sample preparation is too invasive but provides new challenges related to the repeatability of measurement outcomes. We assess the repeatability of LAESI-MSI by sampling a droplet of [ring-(13)C(6)]l-phenylalanine with known concentration and expressing the resulting variability as a coefficient of variation, c(v). In doing so, we entirely eliminate variability caused by surface morphology or underlying true sample gradients. We determine the limit of detection (LOD) for(13)C(6)-Phe by sampling from droplets with successively decreasing but known concentration. We assess the influence of source geometry on the LOD and repeatability by performing these experiments using four distinct variations of sources: one commercial and three custom-built ones. Finally, we extend our study to leaf and stem samples Arabidopsis thaliana and Gossypium hirsutum. We overcome the challenges of LAESI associated with three-dimensional surface morphology by relying on work previously published. Our measurements on both controlled standard and realistic samples give strong evidence that LAESI-MSI’s repeatability in current implementations is insufficient for MSI in chemical ecology
Double logarithms, , and the NLO DGLAP evolution for the non-singlet component of the nucleon spin structure function,
Theoretical predictions show that at low values of Bjorken the spin
structure function, is influenced by large logarithmic corrections,
, which may be predominant in this region. These corrections are
also partially contained in the NLO part of the standard DGLAP evolution. Here
we calculate the non-singlet component of the nucleon structure function,
, and its first moment, using a unified evolution
equation. This equation incorporates the terms describing the NLO DGLAP
evolution and the terms contributing to the resummation. In order
to avoid double counting in the overlapping regions of the phase-space, a
unique way of including the NLO terms into the unified evolution equation is
proposed. The scheme-independent results obtained from this unified evolution
are compared to the NLO fit to experimental data, GRSV'2000. Analysis of the
first moments of shows that the unified evolution including the
resummation goes beyond the NLO DGLAP analysis. Corrections
generated by double logarithms at low influence the -dependence of the
first moments strongly.Comment: 13 pages, latex, 2 figures; Appendix adde
Spin constraints on Regge predictions and perturbative evolution in high energy collisions
Two key issues in the application of perturbative QCD and Regge predictions
to high energy processes are whether the hard and soft pomerons should be
considered as two separate distinct exchanges and whether the Regge intercepts
are Q^2 independent or not. Models involving a distinct hard pomeron exchange
predict much larger values for the LHC total cross-section. Here we argue that
there is a polarized analogue of this issue in the isovector part of the spin
structure function g_1 and that the spin data appear to favour a distinct hard
exchange.Comment: 8 page
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