3,191 research outputs found
Scattering properties of weakly bound dimers of fermionic atoms
We consider weakly bound diatomic molecules (dimers) formed in a
two-component atomic Fermi gas with a large positive scattering length for the
interspecies interaction. We develop a theoretical approach for calculating
atom-dimer and dimer-dimer elastic scattering and for analyzing the inelastic
collisional relaxation of the molecules into deep bound states. This approach
is based on the single-channel zero range approximation, and we find that it is
applicable in the vicinity of a wide two-body Feshbach resonance. Our results
draw prospects for various interesting manipulations of weakly bound dimers of
fermionic atoms.Comment: extended version of cond-mat/030901
Crystalline phase of strongly interacting Fermi mixtures
We show that the system of weakly bound molecules of heavy and light
fermionic atoms is characterized by a long-range intermolecular repulsion and
can undergo a gas-crystal quantum transition if the mass ratio exceeds a
critical value. For the critical mass ratio above 100 obtained in our
calculations, this crystalline order can be observed as a superlattice in an
optical lattice for heavy atoms with a small filling factor. We also find that
this novel system is sufficiently stable with respect to molecular relaxation
into deep bound states and to the process of trimer formation.Comment: 4 pages, 1 color figure, published versio
Weakly bound dimers of fermionic atoms
We discuss the behavior of weakly bound bosonic dimers formed in a cold Fermi
gas at a large positive scattering length for the interspecies interaction.
We find the exact solution for the dimer-dimer elastic scattering and obtain a
strong decrease of their collisional relaxation and decay with increasing .
The large ratio of the elastic to inelastic rate is promising for achieving
Bose-Einstein condensation of the dimers and cooling the condensed gas to very
low temperatures.Comment: 4 pages, no figure
Production of Long-Lived Ultracold Li2 Molecules from a Fermi gas
We create weakly-bound Li2 molecules from a degenerate two component Fermi
gas by sweeping a magnetic field across a Feshbach resonance. The atom-molecule
transfer efficiency can reach 85% and is studied as a function of magnetic
field and initial temperature. The bosonic molecules remain trapped for 0.5 s
and their temperature is within a factor of 2 from the Bose-Einstein
condensation temperature. A thermodynamical model reproduces qualitatively the
experimental findings
Gauge Coupling Beta Functions in the Standard Model to Three Loops
In this paper we compute the three-loop corrections to the beta functions of
the three gauge couplings in the Standard Model of particle physics using the
minimal subtraction scheme and taking into account Yukawa and Higgs self
couplings.Comment: 4 pages, 1 figure, v2: minor changes, references adde
Renormalization constants and beta functions for the gauge couplings of the Standard Model to three-loop order
We compute the beta functions for the three gauge couplings of the Standard
Model in the minimal subtraction scheme to three loops. We take into account
contributions from all sectors of the Standard Model. The calculation is
performed using both Lorenz gauge in the unbroken phase of the Standard Model
and background field gauge in the spontaneously broken phase. Furthermore, we
describe in detail the treatment of and present the automated setup
which we use for the calculation of the Feynman diagrams. It starts with the
generation of the Feynman rules and leads to the bare result for the Green's
function of a given process.Comment: 44 pages, 9 figures; v2: sign in eq.(29) corrected; final result
unchange
Can Giraffes Become Birds? An Evaluation of Image-to-image Translation for Data Generation
There is an increasing interest in image-to-image translation with
applications ranging from generating maps from satellite images to creating
entire clothes' images from only contours. In the present work, we investigate
image-to-image translation using Generative Adversarial Networks (GANs) for
generating new data, taking as a case study the morphing of giraffes images
into bird images. Morphing a giraffe into a bird is a challenging task, as they
have different scales, textures, and morphology. An unsupervised cross-domain
translator entitled InstaGAN was trained on giraffes and birds, along with
their respective masks, to learn translation between both domains. A dataset of
synthetic bird images was generated using translation from originally giraffe
images while preserving the original spatial arrangement and background. It is
important to stress that the generated birds do not exist, being only the
result of a latent representation learned by InstaGAN. Two subsets of common
literature datasets were used for training the GAN and generating the
translated images: COCO and Caltech-UCSD Birds 200-2011. To evaluate the
realness and quality of the generated images and masks, qualitative and
quantitative analyses were made. For the quantitative analysis, a pre-trained
Mask R-CNN was used for the detection and segmentation of birds on Pascal VOC,
Caltech-UCSD Birds 200-2011, and our new dataset entitled FakeSet. The
generated dataset achieved detection and segmentation results close to the real
datasets, suggesting that the generated images are realistic enough to be
detected and segmented by a state-of-the-art deep neural network.Comment: Accepted for presentation at the Computer on the Beach (COTB'20) 202
Bibliometric analysis of quality function deployment with fuzzy systems
Research on quality function deployment (QFD) with fuzzy systems has increased since the 2000s. The growing number of QFD applications with fuzzy systems indicates worldwide attention on this field of research. Then, two research questions arise: Are there some trends? And, are there some research gaps? This paper presents bibliometric analysis to answer those questions, performed on data from Scopus database, in a total output of 598 documents. Only articles and reviews were searched. China is the leading country in publication and international collaboration (207 published documents, more than a third of total). The main finding of analysis is the trend of QFD integration with fuzzy and multi-criteria decision-making (MCDM) methods. This could be observed with different applications as new product development, quality management, service quality, and supply chain management, to name a few.CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior(undefined
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