vol. 79 | iTHES

Vol. 79, May 11th, 2015


  • Upcoming Events
  • Event report
  • Person of the week

Person of the week

Donald Warren



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.

Upcoming Events

May 12 (Tues) 13:30-16:00
The 5th iTHES Academic-Industrial Lecture:
"Artificial Intelligence : Present and Future"
(Note that the schedule has been changed from the last announcement)

13:30-14:30 Yutaka Matsuo (Univ. Tokyo) Deep learning: present and future
14:30-15:00 Break
15:00-16:00 Koichi Takahashi (QBiC) AI and Science/Technology
Place: Okochi Hall

The seminar on 15th May (Fri.)
Shin'ichiro Ando (Assistant Professor, GRAPPA Institute at University of Amsterdam)
Cosmic gamma-ray and neutrino backgrounds: Astrophysical and dark matter implications
Main Research Building, Room 224-226

June 4 (Thur.) from 2:00 pm
Dr. William Witczak-Krempa (https://www.perimeterinstitute.ca/people/william-witczak-krempa )
Constraining quantum critical dynamics: 2+1D Ising model & beyond
Rm 154&156, Main Research Building, Wako campus, RIKEN
Quantum critical (QC) phase transitions generally lead to the destruction of quasiparticles. The resulting correlated quantum fluid, when thermally excited, displays rich universal dynamics. We establish non-perturbative constraints on the linear-response dynamics of QC systems at finite temperature, in spatial dimensions above one. Specifically, we analyze the large frequency/momentum asymptotics of observables, which we use to derive powerful sum rules. The general results are applied to the O(N) Wilson-Fisher fixed point (CFT), describing the QC Ising and XY models when N=1,2, respectively. We'll contrast the results with Dirac fermions. Our focus will be on the order parameter susceptibility, conductivity, and shear viscosity. Connections to quantum Monte Carlo simulations, experiments and AdS/CFT will be made.
It's based on my recent paper (http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.114.177201 ), and other works with Subir Sachdev.

June 15 (Mon), 2015
RIKEN Wako Main Campus
"Symposium on the Present and Future of iTHES"

It has passed 2 years since the RIKEN iTHES started on June 1, 2013. At this symposium, we will discuss the current status and future perspective of iTHES both from scientific and organizational points of view.
All the iTHES members/researchers/associates are urged to attend this important event.

Event report

Santa Barbara is located at the northwest of Los Angeles with the two hour drive distance. Because of its pleasant climate, spanish colonial architecture and beautiful shoreline, it attracted a lot of celebrities from LA area and is known for many villas owned by movie stars from Hollywood. You can spot a large limousine with a chauffeur waiting outside a fashionable shop or people with black ties and formal dresses dining at a popular restaurant. So it seems to be the least likely place where you'd find a theoretical physicist!
It turns out, however, that Santa Barbara is one of the best place to look for the first-tier theoretical physicists thanks to the presence of the University of California at Santa Barbara. The University is now home to six Nobel Laureates, including Walter Kohn, David Gross and Shuji Nakamura.It also hosts the first Kavli institute, Kavli Institute for Theoretical Physics (KITP). KITP was proposed to be an institute focusing long term visitor programs. One of the first of its kind and very successful one. The campus located at a hilltop looking down the Pacific Ocean where you’d find many surfers waiting for the wave.
Tsukasa Tada of iTHES-phys team revisited Santa Barbara recently for the occasion of a workshop. There were also two seminars held in the previous day of the workshop, as a part of KITP visiting program. Every talk was superb but more impressive was the audience. Almost every time the speakers mentioned some fundamental preceding works, the very authors of these works seemed to be present in the audience (and asked tough questions, of course)! So Santa Barbara will likely continue to attract many fine physicists.

Person of the week

Hello to all my fellow iTHES members from the Nagataki Astrophysical Big Bang laboratory. Long before I arrived at RIKEN, I earned two BS degrees in physics and mathematics at NC State University, which is located in Raleigh, NC, USA. The weather in Raleigh was good preparation for my time here at RIKEN, because it's almost the same there and here. After finishing my undergraduate studies I spent a year in Saitama city working in the public school system (and attending some Urawa Reds football matches). From there I returned to NC State to work on a PhD, which I (finally) completed in March of this year. Now I'm back in Japan and very excited to continue my research.
My topics of interest overlap a great deal with other members (past and present) of the ABBL. My early graduate studies considered supernova remnants and their large-scale three-dimensional structure. I was most interested in how the efficiency of cosmic ray (CR) acceleration affected observations of supernova remnant structure: shocks that place a lot of energy in cosmic rays are very compressible, which can cause detectable differences in their morphology. Since then I have moved on to examining CR acceleration more directly. My current studies focus on CRs accelerated at shocks, but in a very different setting from the shocks of supernova remnants. I now simulate particle acceleration by the ultra-relativistic shocks associated with gamma-ray bursts (GRBs) and their afterglows, including photon production due to the CRs. One very important aspect of this work is the feedback loop between shocks and the particles they accelerate. I am currently working to extend my numerical code to handle this feedback loop at the earliest times of the afterglow. When that is complete the ABBL will be able to model most aspects of GRB photon production, from the prompt emission (the GRB itself) deep into the afterglow phase as the shock slows to non-relativistic speeds.
I hope that my time with ABBL and iTHES will lead to lots of exciting collaborations, and I look forward to many interesting discussions over the next few months and years.