On Haag Duality for Pure States of Quantum Spin Chain

We consider quantum spin chains and their translationally invariant pure states. We prove Haag duality for quasilocal observables localized in semi-infinite intervals when the von Neumann algebras generated by observables localized in these intervals are not type I

Entanglement, Haag-duality and type properties of infinite quantum spin chains

We consider an infinite spin chain as a bipartite system consisting of the left and right half-chain and analyze entanglement properties of pure states with respect to this splitting. In this context we show that the amount of entanglement contained in a given state is deeply related to the von Neumann type of the observable algebras associated to the half-chains. Only the type I case belongs to the usual entanglement theory which deals with density operators on tensor product Hilbert spaces, and only in this situation separable normal states exist. In all other cases the corresponding state is infinitely entangled in the sense that one copy of the system in such a state is sufficient to distill an infinite amount of maximally entangled qubit pairs. We apply this results to the critical XY model and show that its unique ground state provides a particular example for this type of entanglement.Comment: LaTeX2e, 34 pages, 1 figure (pstricks

Color screening in a constituent quark model of hadronic matter

The effect of color screening on the formation of a heavy quark-antiquark ($Q\bar{Q}$) bound state--such as the $J/\psi$ meson--is studied using a constituent-quark model. The response of the nuclear medium to the addition of two color charges is simulated directly in terms of its quark constituents via a string-flip potential that allows for quark confinement within hadrons yet enables the hadrons to separate without generating unphysical long-range forces. Medium modifications to the properties of the heavy meson, such as its energy and its mean-square radius, are extracted by solving Schr\"odinger's equation for the $Q\bar{Q}$ pair in the presence of a (screened) density-dependent potential. The density dependence of the heavy-quark potential is in qualitative agreement with earlier studies of its temperature dependence extracted from lattice calculations at finite temperature. In the present model it is confirmed that abrupt changes in the properties of the $J/\psi$-meson in the hadronic medium ({\it plasma}), correlate strongly with the deconfining phase transition.Comment: 7 pages, 3 figures, submitted to PRC for publication, uses revtex

Heavy Quark Interactions in Finite Temperature QCD

We study the free energy of a heavy quark-antiquark pair in a thermal medium. We constuct a simple ansatz for the free energy for two quark flavors motivated by the Debye-H\"uckel theory of screening.Comment: 4 pages, 4 figures, contribution to the proceedings of the International Conference on Hard and Electromagnetic Probes of High Energy Nuclear Collisions, Ericeira, Portugal, Nov. 4-10, 200

撥音における付加的両唇性について

一般的に日本語の撥音は、後続音の調音位置との逆行同化を引き起こす。しかしNogita &Yamane（2015）は、孤立発話やゆっくりとした速度における発話では、後続音の調音位置に関わらず、撥音が両唇を閉じた状態で調音されるような事例を報告した。本稿では、動的エレクトロパラトグラフィを用いてこうした両唇閉鎖性を伴う撥音の調音動態を調査し、両唇閉鎖性が調音位置の逆行同化と独立して生起するという、いわば二重調音としての調音が起こっていること、また両唇閉鎖性の生起は「より撥音らしい音」を指向した結果であることを述べる。In general, Japanese moraic nasals in syllabic coda positions assimilate to the place of articulation of a following consonant. Nogita and Yamane（forthcoming）, however, discussed that Japanese moraic nasals in isolation or slow speach had higher occurrences of bilabial closure even if the following consonant did not have the bilabial position. This study investigates the articulatory patterns with bilabiality of Japanese moraic nalals by means of Electropalatgraphy（EPG）,and proposes that these patterns are the double articulation with the backward assimilation by a following consonant in order to produce more moraic-nasal-like sounds

C/D モデルにおける閉鎖要素と摩擦要素について

弁別素性の概念はローマン・ヤーコブソン以降、様々な形で研究されてきた。近年でも、弁別素性間の階層理論や過小指定、最適性理論における入力情報の完全指定と多様性といった形で議論が続いている。その中で、これらの概念が持つ多くの利点と、いくつかの問題点が明らかにされてきた。例えば、ソシュールの言う「差異の体系」に関する表示の問題や計算システムの並列性／直列性に関わる問題などが挙げられるであろう。その中で、統率音韻論などの要素理論で採用されている「音韻要素(phonological elements)」は、過小指定や素性階層の性質を反映すると共に、表示の完全性という点でも、離散的カテゴリーとプロトタイプカテゴリーの統合という点でも、こうした問題をクリアできる利点を持つ。しかし、その内部構造については十分な議論がなされていない。本稿では、C/D モデル(藤村2007) に立脚しながら、要素理論における「閉鎖要素」と「摩擦要素」の性質について検討を行う。The concept of distinctive feature has been widely used after it was introduced by Roman Jakobson (Jakobson, Fant & Halle 1952). It has been further extended to incorporate such concepts as feature geometry, underspecification of distinctive features and richness of the base in the Optimality Theory. Even though these approaches have numerous advantages, there are at least two kinds of problems. One is concerned with the interpretation of phonemes: underspecification makes it impossible to use phonemes as indicators of the system of distinction. The other problem is concerned with the parallelism/serialism of the theoretical frameworks. The Element Theory, however, expresses phonemes and phonetic forms as bundles of phonological elements. Using these phonological elements, it is now explicitly specified that a set of distinctive features included in a certain phonological element behaves together. This paper explorers the inner structures of the ‘edge’ element and the ‘noise’ element in the framework of the C/D model (Fujimura 2007)

日本語における音韻要素の内部構造

差異の体系は分節音の構造に本質的な役割を果たす。しかし、要素理論で使われる音韻要素は、こうした体系を直接的には表現できない。そこで本稿では、C/D モデル(藤村2007) に立脚しながら、差異の体系を支える音韻要素の内部構造について検討を行う。The system of distinction plays an essential role in the structures of segmental sounds. The phonological elements of the Element Theory, however, cannot expresses the system of difference directly. This paper explorers the inner structures of the phonological elements that support the system of distinction from the view point of the C/D model (Fujimura 2007)