4,084 research outputs found

    catena-Poly[[(2,2′:6′,2′′-terpyridine-κ3 N,N′,N′′)zinc(II)]-μ-2,2′-oxydibenzo­ato-κ2 O:O′]

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    In the title compound, [Zn(C14H8O5)(C15H11N3)]n, both the ZnII ion and the oxydibenzoate ligand are located on a twofold rotation axis. The ZnII centre is coordinated by three N atoms from a chelating 2,2′:6′,2′′-terpyridine ligand and two O atoms from two 2,2′-oxydibenzoate ligands, forming a distorted trigonal-bipyramidal coordination environment. Further coordination via the 2,2′-oxydibenzoate anions forms a one-dimensional coordination polymer extending parallel to [010]. Aromatic π–π stacking inter­actions are observed between adjacent terpyridine ligands with a centroid–centroid distance of 3.568 (2) Å

    Leptonic ZZ decays in the littlest HiggsHiggs model with T-parity

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    The littlest HiggsHiggs model with T-parity (called the LHTLHT model) predicts the existence of the T-odd leptons, which can generate contributions to some leptonic processes at the one-loop level. We calculate their contributions to the leptonic ZZ decay processes Z→ll′ˉZ\to l\bar{l'}, Z→llˉZ\to l\bar{l}, and Z\rightarro \nu\bar{\nu}. We find that the T-odd leptons can give significant contributions to the branching ratios of these decay processes in most of the parameter space. The experimental measurement values might generate constraints on the free parameters of the LHTLHT model.Comment: 16 pages, 8 figures, minor corrections; final version published in Phys.Rev.

    Automatic Article Commenting: the Task and Dataset

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    Comments of online articles provide extended views and improve user engagement. Automatically making comments thus become a valuable functionality for online forums, intelligent chatbots, etc. This paper proposes the new task of automatic article commenting, and introduces a large-scale Chinese dataset with millions of real comments and a human-annotated subset characterizing the comments' varying quality. Incorporating the human bias of comment quality, we further develop automatic metrics that generalize a broad set of popular reference-based metrics and exhibit greatly improved correlations with human evaluations.Comment: ACL2018; with supplements; Dataset link available in the pape

    Numerical and experimental investigation of nonlinear properties of rubber absorber in rail fastening

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    International audienceA nonlinear dynamic model of a rubber absorber in railway fastening systems is proposed, based on the superposition principle to simulate its nonlinear vibrational behavior. A dynamic experiment was carried out to obtain all model parameters. The accuracy of the model was supported by good agreement between measured and simulated results, and it should therefore be an effective mechanical tool for simulating and characterizing the nonlinear behavior of rubber absorbers in rail fastening systems at particular vibrational modes. Excitation frequency dependency and amplitude dependency of the nonlinear dynamic stiffness were also selected for further study. The results indicate that characteristics of the nonlinear dynamic stiffness are closely associated with both displacement amplitude and frequency, although frequency dependency is not as great as amplitude dependency

    Transverse-Momentum Resummation for Gauge Boson Pair Production at the Hadron Collider

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    We perform the transverse-momentum resummation for W+W−W^{+}W^{-}, ZZZZ, and W±ZW^{\pm}Z pair productions at the next-to-next-to-leading logarithmic accuracy using soft-collinear effective theory for S=8TeV\sqrt{S}=8 \text{TeV} and S=14TeV\sqrt{S}=14 \text{TeV} at the LHC, respectively. Especially, this is the first calculation of W±ZW^{\pm}Z transverse-momentum resummation. We also include the non-perturbative effects and discussions on the PDF uncertainties. Comparing with the next-to-leading logarithmic results, the next-to-next-to-leading logarithmic resummation can reduce the dependence of the transverse-momentum distribution on the factorization scales significantly. Finally, we find that our numerical results are consistent with data measured by CMS collaboration for the ZZZZ production, which have been only reported by the LHC experiments for the unfolded transverse-momentum distribution of the gauge boson pair production so far, within theoretical and experimental uncertainties.Comment: 22 pages, 6 figures, re-versio

    Transverse momentum resummation for color sextet and antitriplet scalar production at the LHC

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    We study the factorization and resummation of the transverse momentum spectrum of the color sextet and antitriplet scalars produced at the LHC based on soft-collinear effective theory. Compared to Z boson and Higgs production, a soft function is required to account for the soft gluon emission from the final-state colored scalar. The soft function is calculated at the next-to-leading order, and the resummation is performed at the approximate next-to-next-to-leading logarithmic accuracy. The non-perturbative effects and PDF uncertainties are also discussed.Comment: 20 pages, 7 figure
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