Polarised deep inelastic scattering accompanied by a forward jet as a probe of the ln⁡2(1/x)\ln^2(1/x) resummation

We argue that the production of forward jets in polarised deep inelastic scattering can be a useful tool for probing the double $ln^2(1/x)$ resummation effects which control the polarised deep inelastic scattering for small values of the Bjorken parameter $x$. We solve the corresponding integral equations generating the double $ln^2(1/x)$ resummation and calculate the differential structure function describing the forward jet production in the small $x$ regime which can possibly be probed by the polarised HERA measurements. We show that these structure functions should exhibit the characteristic increase with decreasing $x/x_J$, where $x_J$ 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 $x$ 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 g1g_1 at Small-x

The singlet contribution to the $g_1(x,Q^2)$ structure function is calculated in the double-logarithmic approximation of perturbative QCD in the region $x \ll 1$. Double logarithmic contributions of the type $(\alpha_s \ln ^2 (1/x))^k$ 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 $x \ll 1$. 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 π+π−\pi^+ \pi^-

We review the results of our studies on the charge and the spin asymmetries in the electroproduction of $\pi^+ \pi^-$ 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, ln2(1/x)ln^2(1/x), and the NLO DGLAP evolution for the non-singlet component of the nucleon spin structure function, g1g_1

Theoretical predictions show that at low values of Bjorken $x$ the spin structure function, $g_1$ is influenced by large logarithmic corrections, $ln^2(1/x)$, 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, $g_1^{NS}=g_1^p-g_1^n$, 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 $ln^2(1/x)$ 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 $g_1^{NS}$ shows that the unified evolution including the $ln^2(1/x)$ resummation goes beyond the NLO DGLAP analysis. Corrections generated by double logarithms at low $x$ influence the $Q^2$-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