九大原子核セミナー

2019年11月22日(金) 16:30〜18:00

講師：Philipp Gubler 氏 (日本原子力研究開発機構)
演題：Studying the phi meson in nuclear matter by simulating low energy pA reactions
場所：ウェスト1号館7階 物理セミナー室2 (W1-A-722室)

概要：The behavior of the phi meson in nuclear matter has attracted renewed interest because of (recent and future) experiments that aim to study its properties in nuclei [1-3]. Theoretically,
many works have however been conducted assuming infinite nuclear matter [4-5], which is not realistic from an experimental point of view. To relate theoretical predictions with experimental observables, a thorough understanding of the actual reaction, in which the phi meson is produced in a nucleus, is required. For the past E325 experiment at KEK [1] and the future E16 experiment at J-PARC [3], this is a pA reaction with initial proton energies between 10 and 30 GeV. To simulate such a reaction, we make use of the PHSD transport approach, which is based on a covariant microscopic transport model [6]. In this framework, the phi meson spectral function obtained theoretically as a function of density, can be used as an input, while the output of the simulation can be compared with experimentally observed dilepton spectrum.
In this presentation, I will give an overview of first results obtained in simulations of the reactions probed at the E325 experiment at KEK.

[1] R. Muto et al., Phys. Rev. Lett. 98, 042501 (2007).
[2] A. Polyanskiy et al., Phys. Lett. B 695, 74 (2011).
[3] K. Aoki (J-PARC E16 Collaboration), arXiv:1502.00703 [nucl-ex].
[4] P. Gubler and K. Ohtani, Phys. Rev. D 90, 094002 (2014).
[5] P. Gubler and W. Weise, Phys. Lett. B 751, 396 (2015).
[6] W. Cassing and E. Bratkovskaya, Phys. Rev. C 78, 034919 (2008).

2019年11月18日(月) 16:30〜18:00

講師：Qi Meng 氏 (南京大学)
演題：Compact $sssc\bar{c}$ pentaquark states predicted by a quark model
場所：ウェスト1号館7階 物理セミナー室3 (W1-A-722室)

概要：Several compact $sssc\bar{c}$ pentaquark resonances are predicted in a potential quark model.
Full five-body calculations are carried out by the use of the Gaussian expansion method, and the relevant baryon-meson thresholds are taken into account explicitly.
Employing the real scaling method, we predict four sharp resonances with compact structures.

2019年10月25日(金) 16:30〜18:00

講師： 岡 眞 氏 (日本原子力研究開発機構)
演題：ダイクォークとヘビーバリオンのスペクトル
場所：ウェスト1号館7階 物理セミナー室3 (W1-A-722室)

概要：近年、ヘビークォークを含むヘビーバリオンや、テトラクォーク、ペンタクォークなどのエキゾティックハドロンの発見に伴い、ハドロン中でのカラーをもったクラスター状態の役割が注目されている。このトークでは、もっとも簡単なカラードクラスターであるダイクォークを構成単位とする有効理論を考える。軽いクォークのカイラルダイナミクスに基づいて、カイラルダイクォーク有効理論を構築して、ヘビーバリオンへの応用を図る
試みを紹介する。

2019年10月23日(火) 13:30〜15:00

講師： Ulugbek Yakhshiev氏 (仁荷大学)
演題：Equations of State from the chiral soliton model
場所：ウェスト1号館7階 物理セミナー室3 (W1-A-722室)

概要：We discuss the modifications of nucleon properties in nuclear matter in the framework of chiral soliton model. The modifications are related to the mesonic atoms at low densities and to the properties of nuclear matter at the saturation density. We analyse the Equations of State of nuclear matter at the broad range of nuclear matter densities. Extrapolations of the model predictions at extreme densities and applications to the neutron star properties are also discussed.

2019年10月17日(木) 16:30〜18:00

講師： 久保野 茂 氏 (RIKEN Nishina Center; IMP of CAS, Lanzhou, China; CNS of Univ. of Tokyo)
演題：中性子星周りでの爆発的重元素合成機構の解明に向けて
(Experimental Challenge to Heavy Element Synthesis under Explosive Burning on Neutron Stars)
場所：ウェスト1号館2階 B-212号室 (W1-B-212室)

概要：Neutron stars are now considered to be very active, and interesting objects for physics and astronomy. Especially for nuclear astrophysics to understand the mechanism, nuclear physics for nuclear matter and the nucleosynthesis are the key subjects. The nucleosynthesis taking place around neutron star (or neutron stars) in a binary system require us to work on all over the N-Z plane of nuclear chart including the region still difficult to approach for explosive nuclear burnings. The kilo-nova observation in a binary neutron star merger gave us a chance to learn the r-process way up to super heavy element region in very neutron-rich side, and the X-ray burst in a binary system of a neutron star and a main sequence star ask us to learn nuclear physics of the rp-process way up to mass 110 region in neutron-deficient side. I will first discuss the basic understanding and the problem of the r-process and the rp-process, and then discuss our current, experimental challenges to study the two processes in nuclear physics, being made in RIBF in Japan and HIRF in China.