14,525 research outputs found
Timelike-helicity form factor from light-cone sum rules with dipion distribution amplitudes
We complete the set of QCD light-cone sum rules for transition
form factors, deriving a new sum rule for the timelike-helicity form factor
in terms of dipion distribution amplitudes. This sum rule, in the leading
twist-2 approximation, is directly related to the pion vector form factor.
Employing a relation between and other form factors we
obtain also the longitudinal-helicity form factor . In this way, all four
(axial-)vector form factors are predicted from light-cone sum
rules with dipion distribution amplitudes. These results are valid for small
dipion masses with large momentum.Comment: 7 pages, 3 figure
Multiplicity Preserving Triangular Set Decomposition of Two Polynomials
In this paper, a multiplicity preserving triangular set decomposition
algorithm is proposed for a system of two polynomials. The algorithm decomposes
the variety defined by the polynomial system into unmixed components
represented by triangular sets, which may have negative multiplicities. In the
bivariate case, we give a complete algorithm to decompose the system into
multiplicity preserving triangular sets with positive multiplicities. We also
analyze the complexity of the algorithm in the bivariate case. We implement our
algorithm and show the effectiveness of the method with extensive experiments.Comment: 18 page
Form Factors from Light-Cone Sum Rules with -meson Distribution Amplitudes
We study form factors using QCD light-cone sum rules with
-meson distribution amplitudes. These form factors describe the semileptonic
decay , and constitute an essential input in
and decays. We employ the
correlation functions where a dipion isospin-one state is interpolated by the
vector light-quark current. We obtain sum rules where convolutions of the
-wave form factors with the time-like pion vector
form factor are related to universal -meson distribution amplitudes. These
sum rules are valid in the kinematic regime where the dipion state has a large
energy and a low invariant mass, and reproduce analytically the known
light-cone sum rules for form factors in the limit of
-dominance with zero width, thus providing a systematics for
so-far-unaccounted corrections to transitions. Using data for the
pion vector form factor, we estimate finite width-effects and the contribution
of excited -resonances to the form factors. We find that
these contributions amount up to in the small dipion mass region
where they can be effectively regarded as a nonresonant (-wave) background
to the transition.Comment: 28 pages, 3 figures. A few comments added. Version published in JHE
Personalized Acoustic Modeling by Weakly Supervised Multi-Task Deep Learning using Acoustic Tokens Discovered from Unlabeled Data
It is well known that recognizers personalized to each user are much more
effective than user-independent recognizers. With the popularity of smartphones
today, although it is not difficult to collect a large set of audio data for
each user, it is difficult to transcribe it. However, it is now possible to
automatically discover acoustic tokens from unlabeled personal data in an
unsupervised way. We therefore propose a multi-task deep learning framework
called a phoneme-token deep neural network (PTDNN), jointly trained from
unsupervised acoustic tokens discovered from unlabeled data and very limited
transcribed data for personalized acoustic modeling. We term this scenario
"weakly supervised". The underlying intuition is that the high degree of
similarity between the HMM states of acoustic token models and phoneme models
may help them learn from each other in this multi-task learning framework.
Initial experiments performed over a personalized audio data set recorded from
Facebook posts demonstrated that very good improvements can be achieved in both
frame accuracy and word accuracy over popularly-considered baselines such as
fDLR, speaker code and lightly supervised adaptation. This approach complements
existing speaker adaptation approaches and can be used jointly with such
techniques to yield improved results.Comment: 5 pages, 5 figures, published in IEEE ICASSP 201
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