3,876 research outputs found
Next-to-leading order QCD predictions for associated production of top squarks and charginos at the CERN LHC
We present the calculations of the complete next-to-leading order (NLO)
inclusive total cross sections for the associated production processes in the Minimal Supersymmetric Standard Model at
the CERN Large Hadron Collider. Our calculations show that the total cross
sections for the production for the lighter top
squark masses in the region 100 GeV 160 GeV can reach 1 pb
in the favorable parameter space allowed by the current precise experiments,
and in other cases the total cross sections generally vary from 10 fb to
several hundred fb except both 500 GeV and the
production channel. Moreover, we find that the
NLO QCD corrections in general enhance the leading order total cross sections
significantly, and vastly reduce the dependence of the total cross sections on
the renormalization/factorization scale, which leads to increased confidence in
predictions based on these results.Comment: 42 pages, 13 figures, RevTex4. Journal-ref adde
A three-loop radiative neutrino mass model with dark matter
We present a model that generates small neutrino masses at three-loop level
due to the existence of Majorana fermionic dark matter, which is stabilized by
a Z2 symmetry. The model predicts that the lightest neutrino is massless. We
show a prototypical parameter choice allowed by relevant experimental data,
which favors the case of normal neutrino mass spectrum and the dark matter with
m \sim 50-135 GeV and a sizable Yukawa coupling. It means that new particles
can be searched for in future e+e- collisions.Comment: 7 pages, 3 figure
via SUSY FCNC couplings in the unconstrained MSSM
We recalculate the branching ratios for () induced by
SUSY FCNC couplings within the general unconstrained MSSM framework using mass
eigenstate approach. Our results show that the branching ratios for these
decays are larger than ones reported in previous literatures in the MSSM with
R-parity conservation, and they can reach , , and
, respectively, for favorable parameter values allowed by current
precise experiments. Thus, the branching ratios for and may be measurable at the LHC.Comment: 15 pages, 3 figures, minor changs in the Table
Spin Correlations in top quark pair production near threshold at the Linear Collider
We investigate the spin correlations in top quark pair production near
threshold at the linear collider. Comparing with the results above
the threshold region, we find that near the threshold region the off-diagonal
basis, the optimized decomposition of the top quark spins above the threshold
region, does not exist, and the beamline basis is the optimal basis, in which
there are the dominant spin components: the up-down (UD) component for scattering and the down-up (DU) component for scattering can
make up more than 50% of the total cross section, respectively.Comment: 12 pages, 3 figures, minor modification
Adaptive Tag Selection for Image Annotation
Not all tags are relevant to an image, and the number of relevant tags is
image-dependent. Although many methods have been proposed for image
auto-annotation, the question of how to determine the number of tags to be
selected per image remains open. The main challenge is that for a large tag
vocabulary, there is often a lack of ground truth data for acquiring optimal
cutoff thresholds per tag. In contrast to previous works that pre-specify the
number of tags to be selected, we propose in this paper adaptive tag selection.
The key insight is to divide the vocabulary into two disjoint subsets, namely a
seen set consisting of tags having ground truth available for optimizing their
thresholds and a novel set consisting of tags without any ground truth. Such a
division allows us to estimate how many tags shall be selected from the novel
set according to the tags that have been selected from the seen set. The
effectiveness of the proposed method is justified by our participation in the
ImageCLEF 2014 image annotation task. On a set of 2,065 test images with ground
truth available for 207 tags, the benchmark evaluation shows that compared to
the popular top- strategy which obtains an F-score of 0.122, adaptive tag
selection achieves a higher F-score of 0.223. Moreover, by treating the
underlying image annotation system as a black box, the new method can be used
as an easy plug-in to boost the performance of existing systems
Next-to-leading order QCD predictions for pair production of neutral Higgs bosons at the CERN Large Hadron Collider
We present the calculations of the complete NLO inclusive total cross
sections for pair production of neutral Higgs bosons through
annihilation in the minimal supersymmetric standard model at the CERN Large
Hadron Collider. In our calculations, we used both the DREG scheme and the DRED
scheme and found that the NLO total cross sections in the above two schemes are
the same. Our results show that the -annihilation contributions can
exceed ones of fusion and annihilation for ,
and productions when is large. In the case of , the
NLO corrections enhance the LO total cross sections significantly, which can
reach a few tens percent, while for , the corrections are relatively
small, and are negative in most parameter space. Moreover, the NLO QCD
corrections can reduce the dependence of the total cross sections on the
renormalization/factorization scale, especially for . We also use the
CTEQ6.1 PDF sets to estimate the uncertainty of LO and NLO total cross
sections, and find that the uncertainty arising from the choice of PDFs
increases with the increasing .Comment: 43 pages, 16 figures, minor changes, some references added, a version
to appear in PR
Evidence of the side jump mechanism in the anomalous Hall effect in paramagnets
Persistent confusion has existed between the intrinsic (Berry curvature) and
the side jump mechanisms of anomalous Hall effect (AHE) in ferromagnets. We
provide unambiguous identification of the side jump mechanism, in addition to
the skew scattering contribution in epitaxial paramagnetic NiCu
thin films, in which the intrinsic contribution is by definition excluded.
Furthermore, the temperature dependence of the AHE further reveals that the
side jump mechanism is dominated by the elastic scattering
Next-to-Leading Order QCD Corrections to the Direct Top Quark Production via Model-independent FCNC Couplings at Hadron Colliders
We calculated the next-to-leading order (NLO) QCD corrections to the cross
sections for direct top quark productions induced by model--independent flavour
changing neutral current couplings at hadron colliders. The NLO results
increase the experimental sensitivity to the anomalous couplings. Our results
show that the NLO QCD corrections enhance the leading order (LO) total cross
sections at the Tevatron Run 2 about 60% for both of and
couplings, and enhance the LO total cross sections at the LHC
about 40% for couplings and 50% for couplings,
respectively. Moreover, the NLO QCD corrections vastly reduce the dependence of
the total cross sections on the renormalization or factorization scale, which
leads to increased confidence in predictions based on these results.Comment: 15 pages, 4 figures; published versio
How are ego-centric networks of researchers coupled?
Scientific knowledge creation can be viewed as social-economic activities, which inspires us to explore researchers' interpersonal capital and its impact on scientific performance. In this study, we investigate on multiple types of interpersonal relationships between researchers, including co-authorship, author citation, and social relation, which are considered as interpersonal capital of researchers. Thus, three types of ego-centric networks (ECNs) are constructed by using the data from Twitter and Web of Science. The composition of social networks and the coupling relationships between ECNs in terms of the same researchers are analyzed. The preliminary results on the field of Cheminformatics show that most researchers tend to interact with research related accounts in social networks. The coupling degree between co-authorship networks and author citation networks is significantly higher than that between co-authorship networks and friend networks. Researchers are more likely to collaborate with the researchers who have close scholarly communication with them than the friends from social networks. This study contributes to the understanding of interpersonal relationship in scientific community. Future research will focus on the impact of interpersonal capital on scientific performance
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