1,534 research outputs found
A next-to-leading order study of photon-pion and pion pair hadro-production in the light of the Higgs boson search at the LHC
We discuss the production of photon-pion and pion pairs with a large
invariant mass at collider energies. We present a study based on a perturbative
QCD calculation at full next-to-leading order accuracy, implemented in the
computer programme DIPHOX. We give estimations for various observables, which
concern the reducible background to the Higgs boson search in the channel H -->
gamma gamma, in the mass range 80-140 GeV at the LHC. We critically discuss the
reliability of these estimates due to our imperfect knowledge of fragmentation
functions at high z and a subtle interplay between higher order corrections and
realistic experimental cuts. We conclude that, whereas the invariant mass
spectrum of photon-pion pairs is theoretically better under control, in the
dipion case large uncertainties remain.Comment: 26 pages Latex, 14 eps figures, replaced by published versio
Stable One-Dimensional Integral Representations of One-Loop N-Point Functions in the General Massive Case: I - Three Point Functions
In this article we provide representations for the one-loop three point
functions in 4 and 6 dimensions in the general case with complex masses. The
latter are part of the GOLEM library used for the computation of one-loop
multileg amplitudes. These representations are one-dimensional integrals
designed to be free of instabilites induced by inverse powers of Gram
determinants, therefore suitable for stable numerical implementations.Comment: 40 pages, 1 figur
A full Next to Leading Order study of direct photon pair production in hadronic collisions
We discuss the production of photon pairs in hadronic collisions, from fixed
target to LHC energies. The study which follows is based on a QCD calculation
at full next-to-leading order accuracy, including single and double
fragmentation contributions, and implemented in the form of a general purpose
computer program of "partonic event generator" type. To illustrate the
possibilities of this code, we present the comparison with observables measured
by the WA70 and D0 collaborations, and some predictions for the irreducible
background to the search of Higgs bosons at LHC in the channel . We also discuss theoretical scale uncertainties for these predictions,
and examine several infrared sensitive situations which deserve further study.Comment: 45 pages Latex, 16 eps files plus some metafont files; replaced by
the version to appear in Eur. Phys. J.
Improving preschoolers\u27 memories for the sources of events: A comparison of two source-monitoring training techniques
Preschoolers have a tendency to confuse the sources of events when recalling information. Two source-monitoring training (SMT) techniques were compared to see whether source confusions can be reduced in 3- to 4-year-old children (N = 37). After watching a puppet-show and story, children were randomly assigned to one of three conditions: two SMT conditions (explicit and implicit) and one control condition (memory training) where they were trained on non-target puppet-show and story events. The explicit method consisted of a clear mention of both sources (story, puppet show) and their modality (hearing and seeing, respectively) during training, specific instruction to utilize the strategy during the target interview and a definition, and clear mention to beware of misleading questions. The implicit condition utilized a general mention of both sources (hear, see) as well as no mention of misleading questions or instruction to continue utilizing the strategy. Children in the control condition were not given source training, but rather were trained to recognize the presence of items in each event. No differences were found between conditions in response to yes-no questions. However planned comparisons revealed differences between the explicit and control groups with regards to source-recognition, with the explicit group performing more accurately with regards to identification. Children in the implicit group were more likely to respond \u27I don\u27t know\u27 in comparison to the control group with regards to open-ended questions. Implications for strategy development are discussed
A critical phenomenological study of inclusive photon production in hadronic collisions
We discuss fixed target and ISR inclusive photon production and attempt a
comparison between theory and experiments. The dependence of the theoretical
predictions on the structure functions, and on the renormalization and
factorization scales is investigated. The main result of this study is that the
data cannot be simultaneously fitted with a single set of scales and structure
functions. On the other hand, there is no need for an additional intrinsic
to force the agreement between QCD predictions and experiments, with
the possible exception of one data set. Since the data cover almost overlapping
kinematical ranges this raises the question of consistency among data sets. A
comparative discussion of some possible sources of experimental uncertainties
is sketched.Comment: 22 pages, 3 tables, 10 figures, Late
First Report of Reticulitermes flavipes (Isoptera: Rhinotermitidae) in Italy
The first record of Reticuliterms flavipes (Kol l?r) (Isoptera: Rhinotermitidae) in Europe was in 1837, in Vienna, Austria, after infested plants im ported from the U.S. were discovered in the green house of the Sch?nbrunn Palace (Kollar 1837). In 1924, R. flavipes was found on the French Atlan tic coast and initially described as a new species, R. santonensis (Feytaud 1924). The synonymy of R. santonensis with R. flavipes was eventually confirmed by mitochondrial DNA analyses (Aus tin et al. 2002). In France, R. flavipes is currently distributed in an area extending from the Gi ronde region up to Paris and Normandy, and causes structural damage to buildings and trees (Lohou et al. 1997). During the 1930s, R. flavipes was discovered in wooden forepoles of channel construction in the steam heating district of Hamburg, Germany, where populations were sup ported by the favorable microclimate (Weidner 1937). Today, populations of R. flavipes remain es tablished in Hamburg, and cause damage to buildings and trees (Hertel & Plarre 2006). In Oct 2008, a subterranean termite infesta tion was discovered by a homeowner in a de tached house and adjacent garden situated in a residential district built in the 1970s in the out skirts of Olgiate Olona (Varese), in northern Italy. Termite workers and soldiers were observed and collected during a structural inspection in Nov 2008. Specimens are maintained in the Marini termite collection at the University of Bologna. Molecular analysis was used to determine the termite species, which were preserved in 100% ethanol prior to DNA extraction. A 684-bp region of the mitochondrial cytochrome oxidase subunit II gene and a 491-bp region of the mitochondrial 16S ribosomal RNA gene were amplified by PCR. Sequencing was performed by Macrogen Inc. (Seoul, South Korea). Closely related sequences were identified from GenBank using the BLAST network service (Altschul et al. 1990) at NCBI. For both genes, nucleotide sequences were identical in the 2 workers (GenBank Accession GU070788 and GU070789). Sequences from the Olgiate Olona house corresponded (97-100% cov erage, 100% similarity for COII sequence; 92 100% coverage, 100% similarity for 16S sequence) to GenBank sequences of R. flavipes from North America and France and of R. arenincola Goell ner (Table 1). This latter species appears to be identical to R. flavipes based on the DNA se quences obtained so far
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