An application of a self-consistent version of RPA to quantum field theory with broken symmetry is presented. Although our approach can be applied to any bosonic field theory, we specifically study the φ theory in 1+1 dimensions. We show that standard RPA approach leads to an instability which can be removed when going to a superior version, i.e. the renormalized RPA. We present a method based ...

Effects of medium polarization are studied for 1S0 pairing in neutron and nuclear matter. The screening potential is calculated in the RPA limit, suitably renormalized to cure the low density mechanical instability of nuclear matter. The selfenergy corrections are consistently included resulting in a strong depletion of the Fermi surface. All medium effects are calculated based on the Brueckner...

We perform RPA (Random Phase Approximation) study of collective excitations in the bose-fermi mixed degenerate gas of Alkali-metal atoms at T = 0. The calculation is done by diagonalization in a model space composed of particle-hole type excitations from the ground state, the latter being obtained from the coupled Gross-Pitaevskii and Thomas-Fermi equations. We investigate strength distribution...

This paper describes HCCL lab’s submission to the Queryby-Singing/Humming(QBSH) task of Music Information Retrieval eXchange(MIREX) 2006. As we do not participate in the second sub-task, this paper will only deal with the Known-Item Retrieval sub-task. In the submitted system, we apply a novel algorithm called Recursive Alignment(RA) to compute the similarity score between query and candidates....

A method is proposed which allows to calculate within the SCRPA theory the occupation numbers via the single particle Green function. This scheme complies with the Hugenholtz van Hove theorem. In an application to the Lipkin model it is found that this prescription gives consistently better results than two other commonly used approximations: lowest order boson expansion and the number operator...

The surface plasmon in simple metal clusters is red-shifted from the Mie frequency, the energy shift being significantly larger than the usual spill-out correction. Here we develop a variational approach to the RPA collective excitations. Using a simple trial form, we obtain analytic expressions for the energy shift beyond the spill-out contribution. We find that the additional red shift is pro...

In this paper, we develop a consistent extension of RPA for bosonic systems. In order to illustrate the method, we consider the case of the anharmonic oscillator. We compare our results with those obtained in mean-field and standard RPA approaches, with the exact ones and show that they are very close to the exact ones.

The characteristics of directionally selective cells in area 17 of the cat are studied using moving random pixel arrays (RPAs) with 50Y0white and 50Y0black pixels. The apparent motion stimulus is similar to that used in human psychophysics [Fredericksen et al. (1993). VisionResearch,33, pp. 1193–1205]. We compare motion sensitivity measured with single-step pixel lifetimes and unlimited pixel I...

An application of a self-consistent version of RPA to quantum field theory with broken symmetry is presented. Although our approach can be applied to any bosonic field theory, we specifically study the φ theory in 1+1 dimensions. We show that standard RPA approach leads to an instability which can be removed when going to a superior version, i.e. the renormalized RPA. We present a method based ...

We use the random phase approximation to describe the muon capture rate on 44Ca,48Ca, 56Fe, 90Zr, and 208Pb. With 40Ca as a test case, we show that the Continuum Random Phase Approximation (CRPA) and the standard RPA give essentially equivalent descriptions of the muon capture process. Using the standard RPA with the free nucleon weak form factors we reproduce the experimental total capture rat...