3,112 research outputs found
Photoproduction of pi+ pi- pairs in a model with tensor-pomeron and vector-odderon exchange
We consider the reaction (gamma p) to (pi+ pi- p) at high energies. Our
description includes dipion production via the resonances rho, omega, rho-prime
and f2, and via non-resonant mechanisms. The calculation is based on a model of
high energy scattering with the exchanges of photon, pomeron, odderon and
reggeons. The pomeron and the C=+1 reggeons are described as effective tensor
exchanges, the odderon and the C=-1 reggeons as effective vector exchanges. We
obtain a gauge-invariant version of the Drell-Soeding mechanism which produces
the skewing of the rho-meson shape. Starting from the explicit formulae for the
matrix element for dipion production we construct an event generator which
comprises all contributions mentioned above and includes all interference
terms. We give examples of total and differential cross sections and discuss
asymmetries which are due to interference of C=+1 and C=-1 exchange
contributions. These asymmetries can be used to search for odderon effects. Our
model is intended to provide all necessary theoretical tools for a detailed
experimental analysis of elastic dipion production for which data exist from
fixed target experiments, from HERA, and are now being collected by LHC
experiments.Comment: 49 page
Aperçu de la richesse en petits mammifÚres du Simplon et découverte de la taupe aveugle Talpa caeca (Savi, 1822) en Valais
Isolation and characterization of a mitochondrially synthesized polypeptide from Neurospora crassa cni-1 mutant
The Task Force for the Diagnosis and Treatment of Chronic Heart Failure of the European Society of Cardiology: Guidelines for the Diagnosis and Treatment of Chronic Heart Failure: reply
Electronic and vibrational spectra of protonated benzaldehyde-water clusters, [BZ-(H2O)nâ€5]H+: evidence for ground-state proton transfer to solvent for n â„ 3.
International audienceVibrational and electronic photodissociation spectra of mass-selected protonated benzaldehyde-(water)n clusters, [BZ-(H2O)n]H(+) with n †5, are analyzed by quantum chemical calculations to determine the protonation site in the ground electronic state (S0) and ÏÏ(*) excited state (S1) as a function of microhydration. IR spectra of [BZ-(H2O)n]H(+) with n †2 are consistent with BZH(+)-(H2O)n type structures, in which the excess proton is localized on benzaldehyde. IR spectra of clusters with n â„ 3 are assigned to structures, in which the excess proton is located on the (H2O)n solvent moiety, BZ-(H2O)nH(+). Quantum chemical calculations at the B3LYP, MP2, and ri-CC2 levels support the conclusion of proton transfer from BZH(+) to the solvent moiety in the S0 state for hydration sizes larger than the critical value nc = 3. The vibronic spectrum of the S1 â S0 transition (ÏÏ(*)) of the n = 1 cluster is consistent with a cis-BZH(+)-H2O structure in both electronic states. The large blueshift of the S1 origin by 2106 cm(-1) upon hydration with a single H2O ligand indicates that the proton affinity of BZ is substantially increased upon S1 excitation, thus strongly destabilizing the hydrogen bond to the solvent. The adiabatic S1 excitation energy and vibronic structure calculated at the ri-CC2/aug-cc-pVDZ level agrees well with the measured spectrum, supporting the notion of a cis-BZH(+)-H2O geometry. The doubly hydrated species, cis-BZH(+)-(H2O)2, does not absorb in the spectral range of 23â000-27â400 cm(-1), because of the additional large blueshift of the ÏÏ(*) transition upon attachment of the second H2O molecule. Calculations predict roughly linear and large incremental blueshifts for the ÏÏ(*) transition in [BZ-(H2O)n]H(+) as a function of n. In the size range n â„ 3, the calculations predict a proton transfer from the (H2O)nH(+) solvent back to the BZ solute upon electronic ÏÏ(*) excitation
Analysis of CBR design value selection methods on flexible pavement design: Colombia case studyb
A comparative analysis was carried out to observe the variation of a flexible pavement structural thickness, due to the use of different meth-ods to calculate the CBR design value, as an essential variable to estimate the Subgrade Resilient Modulus (Mr) through an empirical corre-lation. The Asphalt Institute Method and the Mean Criterion Method were applied to calculate de Design CBR value of a homogeneous roadway division from a representative track section located in the Bolivar Department, Colombia. As a result, the Design Percentiles of the CBR design unit were expanded for the Asphalt Institute method, thus, allowing the approach of more reliable and safe designs, con-sidering that this method limits the selection percentiles to three traffic levels
From log Sobolev to Talagrand: a quick proof
We provide yet another proof of the Otto-Villani theorem from the log Sobolev inequality to the Talagrand transportation cost inequality valid in arbitrary metric measure spaces. The argument relies on the recent develop- ment [2] identifying gradient flows in Hilbert space and in Wassertein space, emphasizing one key step as precisely the root of the Otto-Villani theorem. The approach does not require the doubling property or the validity of the local Poincar\ue9 inequality
Unifying candidate gene and GWAS Approaches in Asthma.
The first genome wide association study (GWAS) for childhood asthma identified a novel major susceptibility locus on chromosome 17q21 harboring the ORMDL3 gene, but the role of previous asthma candidate genes was not specifically analyzed in this GWAS. We systematically identified 89 SNPs in 14 candidate genes previously associated with asthma in >3 independent study populations. We re-genotyped 39 SNPs in these genes not covered by GWAS performed in 703 asthmatics and 658 reference children. Genotyping data were compared to imputation data derived from Illumina HumanHap300 chip genotyping. Results were combined to analyze 566 SNPs covering all 14 candidate gene loci. Genotyped polymorphisms in ADAM33, GSTP1 and VDR showed effects with p-values <0.0035 (corrected for multiple testing). Combining genotyping and imputation, polymorphisms in DPP10, EDN1, IL12B, IL13, IL4, IL4R and TNF showed associations at a significance level between pâ=â0.05 and pâ=â0.0035. These data indicate that (a) GWAS coverage is insufficient for many asthma candidate genes, (b) imputation based on these data is reliable but incomplete, and (c) SNPs in three previously identified asthma candidate genes replicate in our GWAS population with significance after correction for multiple testing in 14 genes
The protective behavior of organic coatings containing carboxylic functional groups on lead metal substrates
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