6,158 research outputs found
Threshold Resummation Effects in Neutral Higgs Boson Production by Bottom Quark Fusion at the CERN Large Hadron Collider
We investigate the QCD effects in the production of neutral Higgs bosons via
bottom quark fusion in both the standard model and the minimal supersymmetric
standard model at the CERN Large Hadron Collider. We include the
next-to-leading order (NLO) QCD corrections (including supersymmetric QCD) and
the threshold resummation effects. We use the soft-collinear effective theory
to resum the large logarithms near threshold from soft gluon emission. Our
results show that the resummation effects can enhance the total cross sections
by about 5% compared with the NLO results.Comment: 29pages, 14 figures, version to appear in Physical Review
Molecular Cloning, Characterization, and Expression Analysis of the CXCR4 Gene from Turbot: Scophthalmus maximus
Chemokine receptor 4 (CXCR4) belongs to the large superfamily of G protein-coupled receptors. The EST sequence of CXCR4 from turbot (Scophthalmus maximus L.) was obtained from a subtractive cDNA library. In the present study, the full-length cDNA sequence of turbot CXCR4 was obtained, and sequence analysis indicated that its primary structure was highly similar to CXCR4 from other vertebrates. Quantitative real-time PCR demonstrated that the highest expression level of turbot CXCR4 was in the spleen following injection with physiological saline (PS). After turbot were challenged with Vibrio harveyi, the lowest expression level of CXCR4 was detected at 8 hours in the spleen and 12 hours in the head kidney, and then increased gradually to 36 hours. These findings suggested that CXCR4 may play a significant role in the immune response of turbot
Next-to-leading order QCD corrections to the single top quark production via model-independent t-q-g flavor-changing neutral-current couplings at hadron colliders
We present the calculations of the complete next-to-leading order (NLO) QCD
effects on the single top productions induced by model-independent
flavor-changing neutral-current couplings at hadron colliders. Our results show
that, for the coupling the NLO QCD corrections can enhance the total
cross sections by about 60% and 30%, and for the coupling by about 50%
and 20% at the Tevatron and LHC, respectively, which means that the NLO
corrections can increase the experimental sensitivity to the FCNC couplings by
about 10%30%. Moreover, the NLO corrections reduce the dependence of the
total cross sections on the renormalization or factorization scale
significantly, which lead to increased confidence on the theoretical
predictions. Besides, we also evaluate the NLO corrections to several important
kinematic distributions, and find that for most of them the NLO corrections are
almost the same and do not change the shape of the distributions.Comment: minor changes, version published in PR
Ab initio study of the giant ferroelectric distortion and pressure induced spin-state transition in BiCoO3
Using configuration-state-constrained electronic structure calculations based
on the generalized gradient approximation plus Hubbard U method, we sought the
origin of the giant tetragonal ferroelectric distortion in the ambient phase of
the potentially multiferroic material BiCoO3 and identified the nature of the
pressure induced spin-state transition. Our results show that a strong Bi-O
covalency drives the giant ferroelectric distortion, which is further
stabilized by an xy-type orbital ordering of the high-spin (HS) Co3+ ions. For
the orthorhombic phase under 5.8 GPa, we find that a mixed HS and low-spin (LS)
state is more stable than both LS and intermediate-spin (IS) states, and that
the former well accounts for the available experimental results. Thus, we
identify that the pressure induced spin-state transition is via a mixed HS+LS
state, and we predict that the HS-to-LS transition would be complete upon a
large volume decrease of about 20%.Comment: 6 pages, 6 figures, 2 table
Context-aware Deep Model for Entity Recommendation in Search Engine at Alibaba
Entity recommendation, providing search users with an improved experience via
assisting them in finding related entities for a given query, has become an
indispensable feature of today's search engines. Existing studies typically
only consider the queries with explicit entities. They usually fail to handle
complex queries that without entities, such as "what food is good for cold
weather", because their models could not infer the underlying meaning of the
input text. In this work, we believe that contexts convey valuable evidence
that could facilitate the semantic modeling of queries, and take them into
consideration for entity recommendation. In order to better model the semantics
of queries and entities, we learn the representation of queries and entities
jointly with attentive deep neural networks. We evaluate our approach using
large-scale, real-world search logs from a widely used commercial Chinese
search engine. Our system has been deployed in ShenMa Search Engine and you can
fetch it in UC Browser of Alibaba. Results from online A/B test suggest that
the impression efficiency of click-through rate increased by 5.1% and page view
increased by 5.5%.Comment: CIKM2019 International Workshop on Entity Retrieval. arXiv admin
note: text overlap with arXiv:1511.08996 by other author
2-{2,6-Bis[bis(4-fluorophenyl)methyl]-4-chlorophenylimino} -3-aryliminobutylnickel(II) bromide complexes: Synthesis, characterization, and investigation of their catalytic behavior
The series of 2-{2,6-bis[di(4-fluorophenyl)methyl]-4-chlorophenylimino}-3- aryliminobutane derivatives (L1-L5) and their nickel(II) dibromide complexes (Ni1-Ni5) were synthesized, and all organic compounds were fully characterized by the Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy and by elemental analysis, while the nickel complexes were characterized by FT-IR spectroscopy, elemental analysis, as well as by single-crystal X-ray diffraction for two representative examples, namely Ni1 and Ni4. A distorted tetrahedral geometry was observed for these four-coordinate nickel complexes. Upon the activation with either Methylaluminoxane or modified methylaluminoxane as co-catalyst, all nickel complex precatalysts showed very high activity toward ethylene polymerization with activities of up to 10 7 g(PE)·mol -1 (Ni)·h -1 , and afforded highly branched polyethylene with a bimodal distribution. © 2014 Elsevier B.V
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