5,971 research outputs found
Scattering Amplitudes For All Masses and Spins
We introduce a formalism for describing four-dimensional scattering
amplitudes for particles of any mass and spin. This naturally extends the
familiar spinor-helicity formalism for massless particles to one where these
variables carry an extra SU(2) little group index for massive particles, with
the amplitudes for spin S particles transforming as symmetric rank 2S tensors.
We systematically characterise all possible three particle amplitudes
compatible with Poincare symmetry. Unitarity, in the form of consistent
factorization, imposes algebraic conditions that can be used to construct all
possible four-particle tree amplitudes. This also gives us a convenient basis
in which to expand all possible four-particle amplitudes in terms of what can
be called "spinning polynomials". Many general results of quantum field theory
follow the analysis of four-particle scattering, ranging from the set of all
possible consistent theories for massless particles, to spin-statistics, and
the Weinberg-Witten theorem. We also find a transparent understanding for why
massive particles of sufficiently high spin can not be "elementary". The Higgs
and Super-Higgs mechanisms are naturally discovered as an infrared unification
of many disparate helicity amplitudes into a smaller number of massive
amplitudes, with a simple understanding for why this can't be extended to
Higgsing for gravitons. We illustrate a number of applications of the formalism
at one-loop, giving few-line computations of the electron (g-2) as well as the
beta function and rational terms in QCD. "Off-shell" observables like
correlation functions and form-factors can be thought of as scattering
amplitudes with external "probe" particles of general mass and spin, so all
these objects--amplitudes, form factors and correlators, can be studied from a
common on-shell perspective.Comment: 79 page
Nuclear wastewater decontamination by 3D-Printed hierarchical zeolite monoliths
3D-printed monoliths of zeolites chabazite and 4A were made, characterized, and shown effective for removing strontium and caesium from water
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T Oligo-Primed Polymerase Chain Reaction (TOP-PCR): A Robust Method for the Amplification of Minute DNA Fragments in Body Fluids.
Body fluid DNA sequencing is a powerful noninvasive approach for the diagnosis of genetic defects, infectious agents and diseases. The success relies on the quantity and quality of the DNA samples. However, numerous clinical samples are either at low quantity or of poor quality due to various reasons. To overcome these problems, we have developed T oligo-primed polymerase chain reaction (TOP-PCR) for full-length nonselective amplification of minute quantity of DNA fragments. TOP-PCR adopts homogeneous "half adaptor" (HA), generated by annealing P oligo (carrying a phosphate group at the 5' end) and T oligo (carrying a T-tail at the 3' end), for efficient ligation to target DNA and subsequent PCR amplification primed by the T oligo alone. Using DNA samples from body fluids, we demonstrate that TOP-PCR recovers minute DNA fragments and maintains the DNA size profile, while enhancing the major molecular populations. Our results also showed that TOP-PCR is a superior method for detecting apoptosis and outperforms the method adopted by Illumina for DNA amplification
Neural plasticity in common forms of chronic headaches
Headaches are universal experiences and among the most common disorders. While headache may be physiological in the acute
setting, it can become a pathological and persistent condition.The mechanisms underlying the transition from episodic to chronic
pain have been the subject of intense study. Using physiological and imaging methods, researchers have identified a number of
different forms of neural plasticity associated with migraine and other headaches, including peripheral and central sensitization,
and alterations in the endogenous mechanisms of pain modulation. While these changes have been proposed to contribute to
headache and pain chronification, some findings are likely the results of repetitive noxious stimulation, such as atrophy of brain
areas involved in pain perception and modulation. In this review, we provide a narrative overview of recent advances on the
neuroimaging, electrophysiological and genetic aspects of neural plasticity associated with the most common forms of chronic
headaches, including migraine, cluster headache, tension-type headache, and medication overuse headache
Detach and Adapt: Learning Cross-Domain Disentangled Deep Representation
While representation learning aims to derive interpretable features for
describing visual data, representation disentanglement further results in such
features so that particular image attributes can be identified and manipulated.
However, one cannot easily address this task without observing ground truth
annotation for the training data. To address this problem, we propose a novel
deep learning model of Cross-Domain Representation Disentangler (CDRD). By
observing fully annotated source-domain data and unlabeled target-domain data
of interest, our model bridges the information across data domains and
transfers the attribute information accordingly. Thus, cross-domain joint
feature disentanglement and adaptation can be jointly performed. In the
experiments, we provide qualitative results to verify our disentanglement
capability. Moreover, we further confirm that our model can be applied for
solving classification tasks of unsupervised domain adaptation, and performs
favorably against state-of-the-art image disentanglement and translation
methods.Comment: CVPR 2018 Spotligh
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