MEM study of true flattening of free energy and the θ\theta term

We study the sign problem in lattice field theory with a $\theta$ term, which reveals as flattening phenomenon of the free energy density $f(\theta)$. We report the result of the MEM analysis, where such mock data are used that `true' flattening of $f(\theta)$ occurs. This is regarded as a simple model for studying whether the MEM could correctly detect non trivial phase structure in $\theta$ space. We discuss how the MEM distinguishes fictitious and true flattening.Comment: Poster presented at Lattice2004(topology), Fermilab, June 21-26, 2004; 3 pages, 3 figure

CPN−1^{N-1} model with the theta term and maximum entropy method

A $\theta$ term in lattice field theory causes the sign problem in Monte Carlo simulations. This problem can be circumvented by Fourier-transforming the topological charge distribution $P(Q)$. This strategy, however, has a limitation, because errors of $P(Q)$ prevent one from calculating the partition function ${\cal Z}(\theta)$ properly for large volumes. This is called flattening. As an alternative approach to the Fourier method, we utilize the maximum entropy method (MEM) to calculate ${\cal Z}(\theta)$. We apply the MEM to Monte Carlo data of the CP$^3$ model. It is found that in the non-flattening case, the result of the MEM agrees with that of the Fourier transform, while in the flattening case, the MEM gives smooth ${\cal Z}(\theta)$.Comment: Talk presented at Lattice2004(topology), Fermilab, June 21-26, 2004; 3 pages, 3 figure

Application of Maximum Entropy Method to Lattice Field Theory with a Topological Term

In Monte Carlo simulation, lattice field theory with a $\theta$ term suffers from the sign problem. This problem can be circumvented by Fourier-transforming the topological charge distribution $P(Q)$. Although this strategy works well for small lattice volume, effect of errors of $P(Q)$ becomes serious with increasing volume and prevents one from studying the phase structure. This is called flattening. As an alternative approach, we apply the maximum entropy method (MEM) to the Gaussian $P(Q)$. It is found that the flattening could be much improved by use of the MEM.Comment: talk at Lattice 2003 (topology), 3 pages with 3 figure

Bulk ferromagnetic tips for spin-polarized scanning tunneling microscopy

金沢大学理工学研究域数物科学系／Ex:Institute of Science and Engineering，Mathematics and PhysicsWe characterized the performance of electrochemically etched bulk Fe and Ni tips as a probe of spin-polarized scanning tunneling microscopy (SP-STM). Through the observation of the striped contrast on the conical spin-spiral structure formed in Mn double layers on a W(110) substrate, the capability of both the tips to detect the magnetic signal was clarified. We also confirmed that the magnetized direction of the Fe and Ni tips can be flipped between the two out-of-plane directions by external magnetic fields. Our results demonstrate that the ex-situ prepared tips are reliable in SP-STM for the samples that are not susceptible to a stray magnetic field. © 2019 Author(s).Embargo Period 12 month

Picture Book Project for All

We wish to share the method of our picture book making project that involves collaboration among language community members, linguists, illustrators, and designers. As case studies of abstraction and application, we report multilingual picture books that we have been producing in four endangered Ryukyuan languages in Japan (Okinoerabu/Tarama/Taketomi/Yonaguni). Two of them have an original story created by a native speaker, and the other two takes up a local traditional folk tale. We will explain (1) the features of the picture book packages and (2) the creation processes of them. They aim at (a) documenting endangered languages, (b) facilitating the language use/learning among the younger generations, and (c) raising local language experts. Each picture book comes as a package of three parts; (i) a multilingual story and illustrations, (ii) a detailed linguistic explanation, and (iii) an audio CD of reading the story. Part-(ii) includes a precise but easy-to-use orthography (modified hiragana) proposed for the target language, a phoneme chart and its explanation, and five-line annotations of the full story (original story in the orthography, Japanese translation, morphologically analyzed representation in IPA and the orthography, and word-by-word translation). Illustration and the story contents of the part-(i) make the picture books attractive by themselves, so that they can even catch the attention of those who are not so interested in the endangered situation of the language. Part-(ii) is dedicated to raise the local community members’ objective knowledge of their language. This is to facilitate the younger generations’ use and learning of the local language along with the part-(iii) audio CD, and to raise local language experts. We emphasize that the creation process of a picture book plays an important role in language revitalization. Language community members actively participate in the creation process; they receive a systematic training by the field linguists who have been writing the reference grammar, and become able to describe their language in technical manner. This can be seen as an empowerment of the language community members aiming that they can proceed to future projects receiving less and less support from outside experts. We believe that; facilitating creative activities and linguistic knowledge among the language community members develops the idea that they are actively in charge of the language revitalization; preserving traditional stories in a form of visually attractive and useful content is effective for language revitalization. Our self-ran cloud funding system will also be presented