vol. 91 | iTHES

Vol. 91, August 3rd, 2015


  • Announcement
  • Upcoming Events
  • Event report
  • Paper of the week

Paper of the week

Tetsuo Hatsuda


Hadron-Quark Crossover and the Hot Neutron Star at Birth

From the Office

The office of iTHES assistant, Ms.Chikako Oota is situated at the second floor of the main research building, room # 246. The extension number is 3261. She will be at the office from 10 a.m. to 16 p.m.


Yoichiro Nambu: The Passing of a Gentle Genius

This is a beautiful article on late Yoichiro Nambu (Physics Nobel Prize 2008, https://en.wikipedia.org/wiki/Yoichiro_Nambu )
by his former student in Chicago, Madhusree Mukerjee (http://madhusree.com/ ).

Some quotation from the article: "At the Enrico Fermi Institute, where we had our offices, not only was the atmosphere vibrant and exciting, everyone was friendly and helpful. If I had problems with a calculation, my officemates, who were slightly senior to me, were always ready to take the time to show me how to do it. Later I realized that such a cooperative, rather than a competitive, atmosphere in a particle physics group was rare, and everyone attributed it to Nambu's civilizing presence."

Upcoming Events

iTHES seminar

"Advanced Mean Field Theory of Restricted Boltzmann Machine"
Haiping Huang and Taro Toyoizumi (RIKEN Brain Science Institute (BSI))
Date and time: August 3, 3pm-
Place: Main research building, 4th floor, room 433
Learning in restricted Boltzmann machine is typically hard due to the computation of gradients of log-likelihood function. To describe the network state statistics of the restricted Boltzmann machine, we develop an advanced mean field theory based on the Bethe approximation. Our theory provides an efficient message passing based method that evaluates not only the partition function (free energy) but also its gradients without requiring statistical sampling. The results are compared with those obtained by the computationally expensive sampling based method.
Reference: http://journals.aps.org/pre/abstract/10.1103/PhysRevE.91.050101


"Multi-D simulations of Core-Collapse Supernovae"
Dr. Kuo-Chuan Pan (Basel Univ.)
Date and time: Aug. 5 (Wed.), 14:00 - 15:00
Place: room 224-226 in the main research build.

GRB Workshop 2015 at RIKEN

Date: 31st Aug.- 2nd Sep 2015
Place: Suzuki Umetaro Hall
Please join!

Event report

The first COSMO-AI MEETING supported by iTHES was held on July 28 (Tuesday) at room 433 in the main research building.
Motivation of this meeting is to exchange ideas among the researchers in basic science, engineering and industry, and to discuss the future applications of artificial intelligence and machine learning. The fist meeting was organized by S. Wanajo (iTHE-phys) and T. Hatsuda (iTHES-phys).

The original program is show below. Due to many interesting questions and discussions during the talks, the meeting was actually extended to 18:00. The photo is the talk by Astronomer (Dr. Tanaka) talking about how to find faint signals of the explosive astronomical events in the Universe.

Y. Otake (RIKEN Center for Advanced Photonics)
RIKEN Accelerator-driven compact neutron source RANS and infrastructure safety

M. Tanaka (National Astronomical Observatory of Japan)
Finding transient objects in astronomical imaging data: Application of machine learning

H. Liang (RIKEN Nishina Center)
Nuclear mass models with helps of image reconstruction technique?

T. Nagata (MIZUHO Information and Research Institute)
Image processing and machine learning

Paper of the week

Hadron-Quark Crossover and the Hot Neutron Star at Birth

Neutron-star research is an intersection among astrophysics, particle/nuclear physics and condensed matter physics.
In the core-collapsed Type-II supernova explosion, the proto-neutron star with the radius of 100-200 km is formed. During the first few seconds after the core bounce, it undergoes a rapid contraction and evolves into either a ''hot'' neutron star with the radius 10-20 km or a black hole.
The hot hot neutron at birth in quasi-hydrostatic equilibrium is composed of the superdense matter where even the neutrinos are trapped inside? Then the hot neutron star contracts gradually by the neutrino diffusion with the time scale of several tens of seconds and evolves to a nearly ''cold'' neutron star unless another collapse to a black hole does not take place. In our recent paper [1], we have studied the internal structure of the hot neutron star on the basis of the present knowledge of particle and nuclear physics on super dense matter [2] whose mass density becomes even up to 10**12 kg/cc. We hope that the future neutrino detections (e.g. by Super-Kamiokande http://www-sk.icrr.u-tokyo.ac.jp/sk/index-e.html ) from the supernova explosions and the future gravitational wave detections (e.g. by KAGRA http://gwcenter.icrr.u-tokyo.ac.jp/en/ ) from the neutron star mergers would make observational constraints on the properties of hot neutron stars.

[1] K. Masuda, T. Hatsuda and T. Takatsuka, http://arxiv.org/abs/1506.00984
[2] K. Masuda, T. Hatsuda and T. Takatsuka, Astrophys. J.764, 12 (2013) http://iopscience.iop.org/0004-637X/764/1/12/article