141 research outputs found
Sieving parton distribution function moments via the moment problem
Reconstructing parton distribution function (PDF) from the corresponding
Mellin moments belongs to a classical mathematical problem: the moment problem,
which has been overlooked for years in the contemporary hadron community. We
propose the strategy to sieve the moments leveraging PDF properties such as
continuity, unimodality, and symmetry. Through an error-inclusive sifting
process, we refine three sets of lattice QCD PDF moments. This refinement
significantly reduces the errors, particularly for higher order moments, and
locates the peak of PDF simultaneously. As our method is universally applicable
to PDF moments from any methodology, we strongly advocate its integration into
all PDF moment calculations.Comment: 6 pages, 2 figure
Reconstructing parton distribution function based on maximum entropy method
A new method based on the maximum entropy principle for reconstructing the
parton distribution function (PDF) from moments is proposed. Unlike traditional
methods, the new method no longer needs to introduce any artificial
assumptions. For the case of moments with errors, we introduce Gaussian
functions to soften the constraints of moments. A series of tests are conducted
to comprehensively evaluate the validity and reconstruction efficiency of this
new method. And these tests indicate that our method is reasonable and can
achieve high-quality reconstruction with at least the first six moments as
input. Finally, we select a set of lattice QCD results regarding moments as
input and provide reasonable reconstruction results.Comment: 6 pages, 8 figure
Pion scalar, vector and tensor form factors from a contact interaction
The pion scalar, vector and tensor form factors are calculated within a
symmetry-preserving contact interaction model (CI) of quantum chromodynamics
(QCD), encompassed within a Dyson-Schwinger and Bethe-Salpeter equations
approach. In addition to the traditional rainbow-ladder truncation, a modified
interaction kernel for the Bethe-Salpeter equation is adopted. The implemented
kernel preserves the vector and axial-vector Ward-Takahashi identities, while
also providing additional freedom. Consequently, new tensor structures are
generated in the corresponding interaction vertices, shifting the location of
the mass poles appearing in the quark-photon and quark tensor vertex and
yielding a notorious improvement in the final results. Despite the simplicity
of the CI, the computed form factors and radii are compatible with recent
lattice QCD simulations.Comment: 11 pages, 8 figure
Multi-Level Factorisation Net for Person Re-Identification
Key to effective person re-identification (Re-ID) is modelling discriminative
and view-invariant factors of person appearance at both high and low semantic
levels. Recently developed deep Re-ID models either learn a holistic single
semantic level feature representation and/or require laborious human annotation
of these factors as attributes. We propose Multi-Level Factorisation Net
(MLFN), a novel network architecture that factorises the visual appearance of a
person into latent discriminative factors at multiple semantic levels without
manual annotation. MLFN is composed of multiple stacked blocks. Each block
contains multiple factor modules to model latent factors at a specific level,
and factor selection modules that dynamically select the factor modules to
interpret the content of each input image. The outputs of the factor selection
modules also provide a compact latent factor descriptor that is complementary
to the conventional deeply learned features. MLFN achieves state-of-the-art
results on three Re-ID datasets, as well as compelling results on the general
object categorisation CIFAR-100 dataset.Comment: To Appear at CVPR201
Scalable and Effective Deep CCA via Soft Decorrelation
Recently the widely used multi-view learning model, Canonical Correlation
Analysis (CCA) has been generalised to the non-linear setting via deep neural
networks. Existing deep CCA models typically first decorrelate the feature
dimensions of each view before the different views are maximally correlated in
a common latent space. This feature decorrelation is achieved by enforcing an
exact decorrelation constraint; these models are thus computationally expensive
due to the matrix inversion or SVD operations required for exact decorrelation
at each training iteration. Furthermore, the decorrelation step is often
separated from the gradient descent based optimisation, resulting in
sub-optimal solutions. We propose a novel deep CCA model Soft CCA to overcome
these problems. Specifically, exact decorrelation is replaced by soft
decorrelation via a mini-batch based Stochastic Decorrelation Loss (SDL) to be
optimised jointly with the other training objectives. Extensive experiments
show that the proposed soft CCA is more effective and efficient than existing
deep CCA models. In addition, our SDL loss can be applied to other deep models
beyond multi-view learning, and obtains superior performance compared to
existing decorrelation losses.Comment: To Appear at CVPR201
Disjoint Label Space Transfer Learning with Common Factorised Space
In this paper, a unified approach is presented to transfer learning that
addresses several source and target domain label-space and annotation
assumptions with a single model. It is particularly effective in handling a
challenging case, where source and target label-spaces are disjoint, and
outperforms alternatives in both unsupervised and semi-supervised settings. The
key ingredient is a common representation termed Common Factorised Space. It is
shared between source and target domains, and trained with an unsupervised
factorisation loss and a graph-based loss. With a wide range of experiments, we
demonstrate the flexibility, relevance and efficacy of our method, both in the
challenging cases with disjoint label spaces, and in the more conventional
cases such as unsupervised domain adaptation, where the source and target
domains share the same label-sets.Comment: AAAI-1
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