1,327 research outputs found
Ab initio lattice results for Fermi polarons in two dimensions
We investigate the attractive Fermi polaron problem in two dimensions using
non-perturbative Monte Carlo simulations. We introduce a new Monte Carlo
algorithm called the impurity lattice Monte Carlo method. This algorithm
samples the path integral in a computationally efficient manner and has only
small sign oscillations for systems with a single impurity. As a benchmark of
the method, we calculate the universal polaron energy in three dimensions in
the scale-invariant unitarity limit and find agreement with published results.
We then present the first fully non-perturbative calculations of the polaron
energy in two dimensions and density correlations between the impurity and
majority particles in the limit of zero range interactions. We find evidence
for a smooth crossover transition from fermionic quasiparticle to molecular
state as a function of interaction strength.Comment: Includes new results on density-density correlations. Final version
as will appear in Phys. Rev. Let
Precision benchmark calculations for four particles at unitarity
The unitarity limit describes interacting particles where the range of the
interaction is zero and the scattering length is infinite. We present precision
benchmark calculations for two-component fermions at unitarity using three
different ab initio methods: Hamiltonian lattice formalism using iterated
eigenvector methods, Euclidean lattice formalism with auxiliary-field
projection Monte Carlo, and continuum diffusion Monte Carlo with fixed and
released nodes. We have calculated the ground state energy of the unpolarized
four-particle system in a periodic cube as a dimensionless fraction of the
ground state energy for the non-interacting system. We obtain values 0.211(2)
and 0.210(2) using two different Hamiltonian lattice representations, 0.206(9)
using Euclidean lattice, and an upper bound of 0.212(2) from fixed-node
diffusion Monte Carlo. Released-node calculations starting from the fixed-node
result yield a decrease of less than 0.002 over a propagation of 0.4/E_F in
Euclidean time, where E_F is the Fermi energy. We find good agreement among all
three ab initio methods.Comment: 23 pages, 7 figures, final version to appear in Phys. Rev.
Micro-movements of the ankle joint during running acceleration:Effects on ground reaction forces, body kinematics and muscle activity
Age Detection Through Keystroke Dynamics From User Authentication Failures
In this paper an incident response approach is proposed for handling detections of authentication failures in systems that employ dynamic biometric authentication and more specifically keystroke user recognition. The main component of the approach is a multi layer perceptron focusing on the age classification of a user. Empirical findings show that the classifier can detect the age of the subject with a probability that is far from the uniform random distribution, making the proposed method suitable for providing supporting yet circumstantial evidence during e-discovery
Benchmark calculations for elastic fermion-dimer scattering
We present continuum and lattice calculations for elastic scattering between
a fermion and a bound dimer in the shallow binding limit. For the continuum
calculation we use the Skorniakov-Ter-Martirosian (STM) integral equation to
determine the scattering length and effective range parameter to high
precision. For the lattice calculation we use the finite-volume method of
L\"uscher. We take into account topological finite-volume corrections to the
dimer binding energy which depend on the momentum of the dimer. After
subtracting these effects, we find from the lattice calculation kappa a_fd =
1.174(9) and kappa r_fd = -0.029(13). These results agree well with the
continuum values kappa a_fd = 1.17907(1) and kappa r_fd = -0.0383(3) obtained
from the STM equation. We discuss applications to cold atomic Fermi gases,
deuteron-neutron scattering in the spin-quartet channel, and lattice
calculations of scattering for nuclei and hadronic molecules at finite volume.Comment: 16 pages, 5 figure
Topological phases for bound states moving in a finite volume
We show that bound states moving in a finite periodic volume have an energy
correction which is topological in origin and universal in character. The
topological volume corrections contain information about the number and mass of
the constituents of the bound states. These results have broad applications to
lattice calculations involving nucleons, nuclei, hadronic molecules, and cold
atoms. We illustrate and verify the analytical results with several numerical
lattice calculations.Comment: 4 pages, 1 figure, version to appear in Phys. Rev. D Rapid
Communication
The running coupling method with next-to-leading order accuracy and pion, kaon elm form factors
The pion and kaon electromagnetic form factors are calculated at
the leading order of pQCD using the running coupling constant method. In
calculations the leading and next-to-leading order terms in
expansion in terms of are taken into
account. The resummed expression for is found. Results of numerical
calculations for the pion (asymptotic distribution amplitude) are presented.Comment: 9 pages, 1 figur
Assessment of ice mélange impacts on tidewater glacier dynamics using high resolution ICEYE imagery
Publisher PD
How Virtual Reality is used when involving healthcare staff in the design process
The design process of a new hospital is often recognized as a complex task involving a diverse group of actors. The most common information media used today are project related documents and drawings. Hospital users\ub4 ability to interpret information through these varies. This affects the design feedback from users. However, an increasing use of Virtual Reality (VR) support possibilities to facilitate better understanding. This paper presents six case studies of hospital design projects, where VR has been used with the purpose of involving end-users, investigating how and when VR has been implemented and which effects and experiences that could be noted.The findings show different levels of involvement, engagement, collaboration, and interactivity. Using VR contributes throughout the design process but is dependent on purpose and setup. Furthermore, there is a strong connection between engagement and the interactivity of the VR model
A comparison of high-mobility group-box 1 protein, lipopolysaccharide-binding protein and procalcitonin in severe community-acquired infections and bacteraemia: a prospective study
- …