Fast computation of MadGraph amplitudes on graphics processing unit (GPU)

Continuing our previous studies on QED and QCD processes, we use the graphics processing unit (GPU) for fast calculations of helicity amplitudes for general Standard Model (SM) processes. Additional HEGET codes to handle all SM interactions are introduced, as well assthe program MG2CUDA that converts arbitrary MadGraph generated HELAS amplitudess(FORTRAN) into HEGET codes in CUDA. We test all the codes by comparing amplitudes and cross sections for multi-jet srocesses at the LHC associated with production of single and double weak bosonss a top-quark pair, Higgs boson plus a weak boson or a top-quark pair, and multisle Higgs bosons via weak-boson fusion, where all the heavy particles are allowes to decay into light quarks and leptons with full spin correlations. All the helicity amplitudes computed by HEGET are found to agree with those comsuted by HELAS within the expected numerical accuracy, and the cross sections obsained by gBASES, a GPU version of the Monte Carlo integration program, agree wish those obtained by BASES (FORTRAN), as well as those obtained by MadGraph. The performance of GPU was over a factor of 10 faster than CPU for all processes except those with the highest number of jets.Comment: 37 pages, 12 figure

Weak boson fusion production of supersymmetric particles at the LHC

We present a complete calculation of weak boson fusion production of colorless supersymmetric particles at the LHC, using the new matrix element generator SUSY-MadGraph. The cross sections are small, generally at the attobarn level, with a few notable exceptions which might provide additional supersymmetric parameter measurements. We discuss in detail how to consistently define supersymmetric weak couplings to preserve unitarity of weak gauge boson scattering amplitudes to fermions, and derive sum rules for weak supersymmetric couplings.Comment: 24 p., 3 fig., 9 tab., published in PRD; numbers in Table IV corrected to those with kinematic cuts cite

On Capillary Path Systems In Steep Mountain Areas

This paper describes a high-density path network in a steep mountain area which supports intensive, high quality forestry in Osaka, Japan. The network, which may be likened to a capillary vessel system, makes it possible to: undertake intensive treatment of forests; effect a selective harvest of small, scattered product volumes; change the harvesting method from cable logging (which requires greater worker skill and results in high costs) to one in which products are removed from the stump area by grapple boom cranes located on roads. This network consists of a series of 2.0m wide paths which run parallel to the contour lines and a steep (but very solid) main road (2.5m wide) connecting the paths. The former are branch lines (rib paths) used primarily for extraction and the latter (which is paved with concrete) is the main line (backbone) used for access to the branch lines. In this network, the maximum gradient is 30%, the maximum height of embankment is 1.4 m, the minimum turning radius is 6 m, road density is 222.94 m/ha, correction-factor of shape V = 1.421, correction factor of real skidding distance Ô = 1.215, and the development percentage is 77.9%. Data shows that the correction factors approach 1.0 as the road density is increased, even in mountainous landforms of the type described

PCR-RFLP and sequencing analysis of ribosomal DNA of Bursaphelenchus nematodes related to pine wilt disease

La réaction en chaîne des polymérases/polymorphisme des fragments de restriction (PCR-RFLP) a été utilisée pour séparer des isolats du nématode #Bursaphelenchus. Les isolats de #B. xylophilus examinés provenaient du Japon, des USA, de Chine et du Canada, et ceux de #B. mucronatus du Japon, de Chine et de la France. L'ADN ribosomal contenant le gène 5.8S, les segments de transciption interne 1 et 2, et les segments partiels des gènes 18S et 28S ont été amplifiés par PCR. La digestion des produits amplifiés provenant de chaque isolat à l'aide de douze endonucléases de restriction et l'examen des données en RFLP qui en découlent révèlent, par une analyse en grappe, une séparation significative entre #B. xylophilus et #B. mucronatus. Parmi les isolats de #B. xylophilus examinés, les isolats pathogènes du Japon, ceux de Chine et des USA étaient tous identiques, tandis que les isloats non pathogènes du Japon étaient légèrement distincts et que ceux du Canada formaient une grappe séparée. Parmi les isolats de #B. mucronatus, deux isolats provenant du Japon étaient très semblables ; de même un autre isolat du Japon et un isolat de Chine étaient identiques. Les données provenant des séquences d'ADN montrent 98 différences (substitution nucléotidiques ou séparations) dans les 884 paires de bases examinées chez les isolats de #B. xylophilus et #B. mucronatus. Les données provenant des séquences d'ADN chez #Aphelenchus avenae et #Aphelenchoides fragariae diffèrent non seulement de celles des #Bursaphelenchus mais aussi entre elles. Afin de préciser les relations phylogéniques de ces espèces, les données séquentielles du gène 5.8S provenant de l'ADN ribosomal ont été examinées... (D'après résume d'auteur

Monte Carlo integration on GPU

We use a graphics processing unit (GPU) for fast computations of Monte Carlo integrations. Two widely used Monte Carlo integration programs, VEGAS and BASES, are parallelized on GPU. By using $W^{+}$ plus multi-gluon production processes at LHC, we test integrated cross sections and execution time for programs in FORTRAN and C on CPU and those on GPU. Integrated results agree with each other within statistical errors. Execution time of programs on GPU run about 50 times faster than those in C, and more than 60 times faster than the original FORTRAN programs.Comment: 6 pages, 2 figure

Calculation of HELAS amplitudes for QCD processes using graphics processing unit (GPU)

We use a graphics processing unit (GPU) for fast calculations of helicity amplitudes of quark and gluon scattering processes in massless QCD. New HEGET ({\bf H}ELAS {\bf E}valuation with {\bf G}PU {\bf E}nhanced {\bf T}echnology) codes for gluon self-interactions are introduced, and a C++ program to convert the MadGraph generated FORTRAN codes into HEGET codes in CUDA (a C-platform for general purpose computing on GPU) is created. Because of the proliferation of the number of Feynman diagrams and the number of independent color amplitudes, the maximum number of final state jets we can evaluate on a GPU is limited to 4 for pure gluon processes ($gg\to 4g$), or 5 for processes with one or more quark lines such as $q\bar{q}\to 5g$ and $qq\to qq+3g$. Compared with the usual CPU-based programs, we obtain 60-100 times better performance on the GPU, except for 5-jet production processes and the $gg\to 4g$ processes for which the GPU gain over the CPU is about 20