Soft-gluon Resummation for High-pT Inclusive-Hadron Production at COMPASS

We study the cross section for the photoproduction reaction gamma N -> h X in fixed-target scattering at COMPASS, where the hadron h is produced at large transverse momentum. We investigate the role played by higher-order QCD corrections to the cross section. In particular we address large logarithmic "threshold" corrections to the rapidity dependent partonic cross sections, which we resum to all orders at next-to-leading accuracy. In our comparison to the experimental data we find that the threshold contributions are large and improve the agreement between data and theoretical predictions significantly.Comment: 13 pages, 7 figures, journal versio

FASTCUDA: Open Source FPGA Accelerator & Hardware-Software Codesign Toolset for CUDA Kernels

Using FPGAs as hardware accelerators that communicate with a central CPU is becoming a common practice in the embedded design world but there is no standard methodology and toolset to facilitate this path yet. On the other hand, languages such as CUDA and OpenCL provide standard development environments for Graphical Processing Unit (GPU) programming. FASTCUDA is a platform that provides the necessary software toolset, hardware architecture, and design methodology to efficiently adapt the CUDA approach into a new FPGA design flow. With FASTCUDA, the CUDA kernels of a CUDA-based application are partitioned into two groups with minimal user intervention: those that are compiled and executed in parallel software, and those that are synthesized and implemented in hardware. A modern low power FPGA can provide the processing power (via numerous embedded micro-CPUs) and the logic capacity for both the software and hardware implementations of the CUDA kernels. This paper describes the system requirements and the architectural decisions behind the FASTCUDA approach

Diquark Condensates and Compact Star Cooling

The effect of color superconductivity on the cooling of quark stars and neutron stars with large quark cores is investigated. Various known and new quark-neutrino processes are studied. As a result, stars being in the color flavor locked (CFL) color superconducting phase cool down extremely fast. Quark stars with no crust cool down too rapidly in disagreement with X-ray data. The cooling of stars being in the N_f =2 color superconducting (2SC) phase with a crust is compatible with existing X-ray data. Also the cooling history of stars with hypothetic pion condensate nuclei and a crust does not contradict the data.Comment: 10 pages, 5 figures, accepted for publication in Ap

Diquark Masses from Lattice QCD

We present first results for diquark correlation functions calculated in Landau gauge on the lattice. Masses have been extracted from the long distance behaviour of these correlation functions. We find that the ordering of diquark masses with spin 0 and 1 states in colour anti-triplet and sextet channels is in accordance with instanton motivated interaction models. Although we find evidence for an attractive interaction in colour anti-triplet states with a splitting between spin 0 and spin 1 diquarks that can account for the mass splitting between the nucleon and the delta, there is no evidence for a deeply bound diquark state.Comment: 12 pages, LaTeX2e uses revtex, 3 EPS-figures, small corrections, references update

Confining Effective Theories Based on Instantons and Merons

An effective theory based on ensembles of either regular gauge instantons or merons is shown to produce confinement in SU(2) Yang-Mills theory. When the scale is set by the string tension, the action density, topological susceptibility and low-lying glueball spectrum are similar to those arising in lattice QCD. The physical mechanism producing confinement is explained, and a number of analytical insights into the effective theory are presented.Comment: 53 pages, 41 figure

Control of article use in SAE and AAE-speaking children

Designing a test battery for language that is appropriate across dialects is difficult. Many of theitems traditionally studied to assess the sophistication of preschoolers’ speech include inflections such astense and plurality that behave differently across dialects, resulting in the mis-assignment of clinical statusto normal speakers of dialects such as African American English. One strategy towards solution of thisdilemma has been to choose items that involve tests of linguistic knowledge that have no established dialectdifferences. Recent work on articles in English suggests there is promise in this area, since a) there are no established dialect differences in the use of definite and indefinite articles between AAE andSAE.b) SLI children, on the other hand, show significant difficulties using articles appropriately (Ramos, 1999) Given those two premises, it is clear that the article items may be responded to in the same way by childrenregardless of dialect but dependent on their clinical status. The purpose of this study was to establish abaseline with normally-developing children and confirm that there are no dialect differences for 3-7 yearolds.Previous studies of article use have been fraught with methodological difficulties, and considerablevariation depending on the methods and materials. Our analysis of the inadequacies of earlier experimentson this topic (see Cziko 1986) led us to design the task so that no objects relevant to the elicitation werepresent during the experiment. That is, we modified a recent procedure by Schafer and de Villiers (2000),which gets around the materials problem by using none! In effect, the children are asked questions that theyanswer “out of their heads”, a procedure that might also lessen the disadvantage of children who are lessused to test-type book materials. The purpose of the study was to elicit from children noun phrasescontaining the articles a and the under conditions that controlled for the maximum number ofextralinguistic contributions to familiarity and uniqueness

Hints on the power corrections from current correlators in x-space

We consider an interpretation of the recent lattice data on the current-current correlators in the x-space. The data indicate rather striking difference between (axial)vector and (pseudo)scalar channels which goes beyond the predictions of the standard non-perturbative models. We argue that if the difference is to be explained by power corrections, there is a unique choice of the form of the correction. We discuss the emerging picture of the power corrections.Comment: Some misprints corrected. 8 pages including 2 tables and 2 figure