1,425 research outputs found
Searching for the signal of dark matter and photon associated production at the LHC beyond leading order
We study the signal of dark matter and photon associated production induced
by the vector and axial-vector operators at the LHC, including the QCD
next-to-leading order (NLO) effects. We find that the QCD NLO corrections
reduce the dependence of the total cross sections on the factorization and
renormalization scales, and the factors increase with the increasing of the
dark matter mass, which can be as large as about 1.3 for both the vector and
axial-vector operators. Using our QCD NLO results, we improve the constraints
on the new physics scale from the results of the recent CMS experiment.
Moreover, we show the Monte Carlo simulation results for detecting the
\gamma+\Slash{E}_{T} signal at the QCD NLO level, and present the integrated
luminosity needed for a discovery at the 14 TeV LHC . If the signal
is not observed, the lower limit on the new physics scale can be set.Comment: 19 pages, 18 figures, 2 tables, version published in Phys.Rev.
Phenomenology of an Extended Higgs Portal Inflation Model after Planck 2013
We consider an extended inflation model in the frame of Higgs portal model,
assuming a nonminimal coupling of the scalar field to the gravity. Using the
new data from Planck and other relevant astrophysical data, we obtain
the relation between the nonminimal coupling and the self-coupling
needed to drive the inflation, and find that this inflationary model
is favored by the astrophysical data. Furthermore, we discuss the constraints
on the model parameters from the experiments of particle physics, especially
the recent Higgs data at the LHC.Comment: 21 pages, 8 figures; Version published in EPJ
Constraints on flavor-changing neutral-current couplings from the signal of associated production with QCD next-to-leading order accuracy at the LHC
We study a generic Higgs boson and a top quark associated production via
model-independent flavor-changing neutral-current couplings at the LHC,
including complete QCD next-to-leading order (NLO) corrections to the
production and decay of the top quark and the Higgs boson. We find that QCD NLO
corrections can increase the total production cross sections by about 48.9% and
57.9% for the and coupling induced processes at the LHC,
respectively. After kinematic cuts are imposed on the decay products of the top
quark and the Higgs boson, the QCD NLO corrections are reduced to 11% for the
coupling induced process and almost vanish for the coupling induced
process. Moreover, QCD NLO corrections reduce the dependence of the total cross
sections on the renormalization and factorization scales. We also discuss
signals of the associated production with the decay mode t \rightarrow
bl^{+}E \slash_{T}, H \rightarrow b\bar{b} and production with the
decay mode \bar{t} \rightarrow H\bar{q}, t\rightarrow bl^{+}E \slash_{T}. Our
results show that, in some parameter regions, the LHC may observe the above
signals at the level. Otherwise, the upper limits on the FCNC
couplings can be set.Comment: 28 pages, 14 figures, 5 tables; version published in PR
Architecture Decisions in AI-based Systems Development: An Empirical Study
Artificial Intelligence (AI) technologies have been developed rapidly, and
AI-based systems have been widely used in various application domains with
opportunities and challenges. However, little is known about the architecture
decisions made in AI-based systems development, which has a substantial impact
on the success and sustainability of these systems. To this end, we conducted
an empirical study by collecting and analyzing the data from Stack Overflow
(SO) and GitHub. More specifically, we searched on SO with six sets of keywords
and explored 32 AI-based projects on GitHub, and finally we collected 174 posts
and 128 GitHub issues related to architecture decisions. The results show that
in AI-based systems development (1) architecture decisions are expressed in six
linguistic patterns, among which Solution Proposal and Information Giving are
most frequently used, (2) Technology Decision, Component Decision, and Data
Decision are the main types of architecture decisions made, (3) Game is the
most common application domain among the eighteen application domains
identified, (4) the dominant quality attribute considered in architecture
decision-making is Performance, and (5) the main limitations and challenges
encountered by practitioners in making architecture decisions are Design Issues
and Data Issues. Our results suggest that the limitations and challenges when
making architecture decisions in AI-based systems development are highly
specific to the characteristics of AI-based systems and are mainly of technical
nature, which need to be properly confronted.Comment: The 30th IEEE International Conference on Software Analysis,
Evolution, and Reengineering (SANER
The development and applications of ultrafast electron nanocrystallography
We review the development of ultrafast electron nanocrystallography as a
method for investigating structural dynamics for nanoscale materials and
interfaces. Its sensitivity and resolution are demonstrated in the studies of
surface melting of gold nanocrystals, nonequilibrium transformation of graphite
into reversible diamond-like intermediates, and molecular scale charge
dynamics, showing a versatility for not only determining the structures, but
also the charge and energy redistribution at interfaces. A quantitative scheme
for three-dimensional retrieval of atomic structures is demonstrated with
few-particle (< 1000) sensitivity, establishing this nanocrystallographic
method as a tool for directly visualizing dynamics within isolated
nanomaterials with atomic scale spatio-temporal resolution.Comment: 33 pages, 17 figures (Review article, 2008 conference of ultrafast
electron microscopy conference and ultrafast sciences
Enhanced Sparsification via Stimulative Training
Sparsification-based pruning has been an important category in model
compression. Existing methods commonly set sparsity-inducing penalty terms to
suppress the importance of dropped weights, which is regarded as the suppressed
sparsification paradigm. However, this paradigm inactivates the dropped parts
of networks causing capacity damage before pruning, thereby leading to
performance degradation. To alleviate this issue, we first study and reveal the
relative sparsity effect in emerging stimulative training and then propose a
structured pruning framework, named STP, based on an enhanced sparsification
paradigm which maintains the magnitude of dropped weights and enhances the
expressivity of kept weights by self-distillation. Besides, to find an optimal
architecture for the pruned network, we propose a multi-dimension architecture
space and a knowledge distillation-guided exploration strategy. To reduce the
huge capacity gap of distillation, we propose a subnet mutating expansion
technique. Extensive experiments on various benchmarks indicate the
effectiveness of STP. Specifically, without fine-tuning, our method
consistently achieves superior performance at different budgets, especially
under extremely aggressive pruning scenarios, e.g., remaining 95.11% Top-1
accuracy (72.43% in 76.15%) while reducing 85% FLOPs for ResNet-50 on ImageNet.
Codes will be released soon.Comment: 26 page
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