3,722 research outputs found
Parity-violating coupling constant from the flavor-conserving effective weak chiral Lagrangian
We investigate the parity-violating pion-nucleon-nucleon coupling constant
, based on the chiral quark-soliton model. We employ an effective
weak Hamiltonian that takes into account the next-to-leading order corrections
from QCD to the weak interactions at the quark level. Using the gradient
expansion, we derive the leading-order effective weak chiral Lagrangian with
the low-energy constants determined. The effective weak chiral Lagrangian is
incorporated in the chiral quark-soliton model to calculate the
parity-violating constant . We obtain a value of about
at the leading order. The corrections from the next-to-leading order
reduce the leading order result by about 20~\%.Comment: 12 page
Effects of nucleon resonances on photoproduction off the neutron reexamined
We investigate photoproduction off the neutron target, i.e., , employing an effective Lagrangian method combining with a Regge
approach. As a background, we consider nucleon exchange in the -channel
diagram and - and -meson Regge trajectories in the channel.
The role of nucleon resonances given in the Review of Particle Data Group in
the range of MeV and the narrow nucleon resonance
is extensively studied. The numerical results of the total and
differential cross sections, double polarization observable , and
helicity-dependent cross sections , are found to
be in qualitative agreement with the recent A2 experimental data. The
predictions of the beam asymmetry are also given.Comment: 12 pages, 6 figure
VR/AR head-mounted display system based measurement and evaluation of dynamic visual acuity
This study evaluated the dynamic visual acuity of candidates by implementing a King–Devick (K-D) test chart in a virtual reality head-mounted display (VR HMD) and an augmented reality head-mounted display (AR HMD). Hard-copy KD (HCKD), VR HMD KD (VHKD), and AR HMD KD (AHKD) tests were conducted in 30 male and female candidates in the age of 10S and 20S and subjective symptom surveys were conducted.
In the subjective symptom surveys, all except one of the VHKD questionnaire items showed subjective symptoms of less than 1 point. In the comparison between HCKD and VHKD, HCKD was measured more rapidly than VHKD in all tests. In the comparison between HCKD and AHKD, HCKD was measured more rapidly than AHKD in Tests 1, 2, and 3. In the comparison between VHKD and AHKD, AHKD was measured more rapidly than VHKD in Tests 1, 2, and 3. In the correlation analyses of test platforms, all platforms were correlated with each other, except for the correlation between HCKD and VHKD in Tests 1 and 2. There was no significant difference in the frequency of errors among Tests 1, 2, and 3 across test platforms.
VHKD and AHKD, which require the body to be moved to read the chart, required longer measurement time than HCKD. In the measurements of each platform, AHKD was measured closer to HCKD than VHKD, which may be because the AHKD environment is closer to the actual environment than the VHKD environment. The effectiveness of VHKD and AHKD proposed in this research was evaluated experimentally. The results suggest that treatment and training could be performed concurrently through the use of clinical test and content development of VHKD and AHKD
A Proposal of Storytelling Direction as a Process of Narrowing the Gap between Designers and Users
OAIID:RECH_ACHV_DSTSH_NO:A201701933RECH_ACHV_FG:RR00200003ADJUST_YN:EMP_ID:A080155CITE_RATE:FILENAME:HCIK2017_디자이너와 사용자의 간극을 좁히는 프로세스로서 스토리텔링 방향성 제안_paper_242_FINAL.pdfDEPT_NM:디자인학부EMAIL:[email protected]_YN:FILEURL:https://srnd.snu.ac.kr/eXrepEIR/fws/file/b8b39b27-ce50-4d0f-b403-08849291b068/linkCONFIRM:
Symmetry-protected flatband condition for Hamiltonians with local symmetry
We derive symmetry-based conditions for tight-binding Hamiltonians with
flatbands to have compact localized eigenstates occupying a single unit cell.
The conditions are based on unitary operators commuting with the Hamiltonian
and associated with local symmetries that guarantee compact localized states
and a flatband. We illustrate the conditions for compact localized states and
flatbands with simple Hamiltonians with given symmetries. We also apply these
results to general cases such as the Hamiltonian with long-range hoppings and
higher-dimensional Hamiltonian.Comment: 7 pages, 2 figure
Nearly Massless Electrons in the Silicon Interface with a Metal Film
We demonstrate the realization of nearly massless electrons in the most
widely used device material, silicon, at the interface with a metal film. Using
angle-resolved photoemission, we found that the surface band of a monolayer
lead film drives a hole band of the Si inversion layer formed at the interface
with the film to have nearly linear dispersion with an effective mass about 20
times lighter than bulk Si and comparable to graphene. The reduction of mass
can be accounted for by repulsive interaction between neighboring bands of the
metal film and Si substrate. Our result suggests a promising way to take
advantage of massless carriers in silicon-based thin-film devices, which can
also be applied for various other semiconductor devices.Comment: 4 pages, 4 figures, accepted for publication in Physical Review
Letter
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