Results 1 - 10 of 329
Results 1 - 10 of 329. Search took: 0.02 seconds
|Sort by: date | relevance|
[en] Anomalous sector of chiral Lagrangian is calculated in a gauge invariant, nonlocal, dynamical quark model. The Wess-Zumino term is proved coming from two kinds of sources, one is independent of and another dependent on dynamical quark self energy Σ(k2). p6 and more higher order anomalous sectors come only from Σ(k2) dependent source. After some cancellation, standard Wess-Zumino action is obtained
[en] From view point of modern field theory, all theories for realistic interaction are effective, which come from some more elementary theory. One main feature of effective theory is that it include infinite number of interaction terms. Effective theory is different with standard renormalizable field theory. Here, the authors focus on a class of special effective theory-effective chiral Lagrangian in strong interaction, discuss its features and present status of its development. The authors do not involve heavy quark effective field theory and NRQCD and the combination of these theories and effective chiral Lagrangian
[en] The south central section of Da Hinggan Mountains, where the Zha Lantun prospecting zones of volcanic type uranium ore, is a high density concentrated distribution area of uranium and polymetallic mineral. This article elaborated uranium metallogenic geological conditions in the south central section of Da Hinggan Mountain, from the tectonic conditions, the source of uranium, the heat source, the space for ore-forming, hydrothermal alteration, the mineralization, and ect. This area has a good prospecting foreground and potentiality. (authors)
[en] Traditionally, research on the phenomenological theory for neutral kaon system use the effective Hamiltonian theory based on the Wigner-Weisskopf approximation. For describing this system precisely, the authors use the state evolution matrix without using the Wigner-Weisskopf approximation and get four complex parameters to describe the CP and CPT violation properties of neutral kaon system. Also the authors have estimated that when the order of experimental resolution reaches to 10-14, the authors will have to use state evolution matrix to describe the neutral kaon system and can not use the effective Hamiltonian theory
[en] Highlights: • The toroidal carbon nanotube interferometer coupled with Majorana fermions is considered. • The terminal current and shot noise have been investigated through equation of motion method. • The Andreev and cross-Andreev reflections contribute to the current and shot noise. • The enhancement of shot noise is generated by the application of Majorana fermions. • The periodic oscillations versus Aharonov–Bohm flux exhibit the controlling of Majorana fermions. - Abstract: The shot noise of a toroidal carbon nanotube (TCN) interferometer coupled with Majorana fermions is deduced from evaluating the current correlation. Many novel channels are opened for electrons to transport, and the energy gap of the semiconducting TCN becomes narrower. The Majorana fermions cause additional current correlations among the normal tunneling currents and Andreev reflection currents, and hence the shot noise and Fano factor are enhanced. The conductance, current, and shot noise are modified by Majorana fermions to exhibit different oscillation and resonance structures. The detailed behaviors of these quantities are quite different from the metal and semiconducting TCNs.
[en] Purpose: To compare the quantitative and subjective image quality in abdominal angiography between dual-energy CT (DECT) at the routine concentration of iodinated contrast agent (300 mg/mL) and conventional 120-kVp single-energy CT (SECT) at the high concentration of contrast agent (370 mg/mL). Materials and methods: Abdominal computed tomography angiography (CTA) was performed in 104 patients, including 56 with conventional 120-kVp SECT at the high concentration of contrast agent and 48 with DECT at the routine concentration of contrast agent. The monochromatic images at the optimal kiloelectron-voltage (keV) of DECT that demonstrated the best contrast-to-noise ratio were reconstructed. The signal intensity and noise in abdominal arteries were comparatively analyzed between DECT and SECT. The image quality and visibility of the branch orders of superior mesenteric artery and renal arteries were further assessed. The radiation doses were recorded. Results: Compared with SECT, DECT demonstrated higher signal intensity, signal-to-noise ratio, and contrast-to-noise ratio (all P < 0.01) with moderately increased noise (40%, P < 0.01) in all abdominal arteries. The image quality of DECT was superior to that of SECT (P < 0.01) as evaluated with a subjective five-point scale system. Visualization of the branches of superior mesenteric artery and renal arteries was also better by DECT (P < 0.01) than SECT. The radiation dose of DECT was slight higher than that of SECT (P < 0.0001). Conclusion: DECT with image reconstruction at the optimal keV provides a high-quality angiographic technique, which allows use of a lower concentration of contrast agent compared with conventional 120-kVp SECT
[en] The Effective Chiral Lagrangian (ECL) for the Pseudoscalar Goldstone Bosons is derived from QCD without making approximations. The coefficients up to p4 order in the ECL are expressed in terms of certain Green's function in QCD
[en] In 1995 National Nuclear Safety Administration issued The Guidelines on Nuclear Equipment Seismic Qualification Tests (HAF-J 0053), which plays a positive role in regulating our activities on nuclear equipment seismic qualification. The portion of multifrequency excitations in The Guidelines requires that the PSD curve calculated from every acceleration time history must envelop the curve of 80% PSD calculated from the required response spectrum in the frequency range of 0.3 Hz to 24 Hz. But, how to deduce the acceptable PSD that is reasonably conservative according to the 'required response spectrum' remains an unresolved issue, which in turn brings much trouble into the nuclear regulatory activities. First, this paper starts from the mainly referenced base document for compiling 'The Guidelines' to analyze the implications and necessity of the PSD requirement. Then, the method is explored to deduce the 'minimum acceptable PSD' from the 'required response spectrum' based on the definitions and calculation equations of response spectrum and PSD, taking into consideration the regulatory principle of 'reasonably conservative'. And lastly, recommendations are put forward on our future works for standards or norms compilation and for nuclear safety supervisions. (authors)
[en] We focus on a new gauge symmetry keeping regularization scheme for momentum integration and point out that dropping out momentum space asymptotic non-logarithmic total derivative divergent integrations in quantum field theory is a simple and natural way to keep the computation program gauge-covariant.