Speaker: Professor Tetsuo HatsudaThe University of Tokyo
Time: 10:30 A.M., Tuesday September 2,2025
Location: Lecture Hall 9409

Abstract:
It is well understood that the most basic building blocks of matter are elementary particles known as quarksHowever, a complete understanding of how quarks form protons, neutrons, and ultimately atomic nuclei remains anopen problem in physics. Over the past several decades, many neutron stars have been observed - compact stellarobjects with masses similar to that of the Sun but with radii of only about 10 kilometers. These objects, sometimesreferred to as "giant atomic nuclei,” exist in extreme conditions that offer valuable opportunities to investigate thebehavior of quarks in dense matter. Understanding the internal structure of neutron stars from a quark-basedperspective has become an important topic that connects particle physics, nuclear physics, and astrophysics.In 2017, the merger of two neutron stars was observed, producing a black hole and emiting gravitational wavesThis event marked the beginning of multi-messengerastronomy and provided a new way to explore the propertiesof dense matter. As gravitational wave observations continue to improve, they may offer new insights into howquarks behave inside neutron stars.In this talk, I will discuss recent progress in efforts to build a coherent picture of physical phenomena that span awide range of scales - from the microscopic world of quarks to the structure of neutron stars and black holesdrawing on examples from my own research.

Speaker Profile:

Tetsuo Hatsuda eared his Doctor of Science in Physics from Kyoto University in 1986 and currently serves as the Executive Director of Science at RlKEN and is an Emeritus Professor of the University of Tokvo, His distinguisheccareer includes key roles such as Program Director at RIKEN iTHEMS and Chief Scientist at the RIKEN NishinCenter. He has held professorial positions at the University of Tokyo and Kyoto University, following researclappointments at CERN, KEK, and multinle institutions in the lnited StatesProf. Hatsuda has been recognized with numerous prestigious awards, including being named an InternationaHonorary Member of the American Academy of Arts and Sciences (2024), the Toray Science and TechnologyAward (2016), and Japan’s Commendation for Science and Technology (2014). He is also a recipient of theTsukuba Prize, the Nishina Memorial Prize, and the Nishinomiya Yukawa Memorial Prize.