37,362 research outputs found
e+ e- -> t anti-t H including decays: on the size of background contributions
We present results for the lowest order cross sections, calculated with the
complete set of the standard model Feynman diagrams, of all possible detection
channels of the associated production of the top quark pair and the light Higgs
boson, which may be used for determination of the top-Higgs Yukawa coupling at
the future e+e- linear collider. We show that, for typical particle
identification cuts, the background contributions are large. In particular, the
QCD background contributions are much bigger than could be expected when taking
into account a possibly low virtuality of exchanged gluons. Moreover, we
include the initial state radiation effects and discuss the dependence of the
cross sections on the Higgs boson and top quark masses.Comment: 13 pages, 1 figure; substantially revised version, accepted for
publication in Eur.Phys.J.
Differentiable Programming Tensor Networks
Differentiable programming is a fresh programming paradigm which composes
parameterized algorithmic components and trains them using automatic
differentiation (AD). The concept emerges from deep learning but is not only
limited to training neural networks. We present theory and practice of
programming tensor network algorithms in a fully differentiable way. By
formulating the tensor network algorithm as a computation graph, one can
compute higher order derivatives of the program accurately and efficiently
using AD. We present essential techniques to differentiate through the tensor
networks contractions, including stable AD for tensor decomposition and
efficient backpropagation through fixed point iterations. As a demonstration,
we compute the specific heat of the Ising model directly by taking the second
order derivative of the free energy obtained in the tensor renormalization
group calculation. Next, we perform gradient based variational optimization of
infinite projected entangled pair states for quantum antiferromagnetic
Heisenberg model and obtain start-of-the-art variational energy and
magnetization with moderate efforts. Differentiable programming removes
laborious human efforts in deriving and implementing analytical gradients for
tensor network programs, which opens the door to more innovations in tensor
network algorithms and applications.Comment: Typos corrected, discussion and refs added; revised version accepted
for publication in PRX. Source code available at
https://github.com/wangleiphy/tensorgra
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