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"Multistrange Nuclei--- Recent Experimental and Theoretical Developments ---"
Prof. Avraham Gal
Sep 20, 2002
講演題目： Multistrange Nuclei--- Recent Experimental and Theoretical Developments ---
講 師 ： Prof. Avraham Gal
(Hebrew University, Israel)
日 時 ： 平成14年9月20日 (金) 10:30-
場 所 ： 北海道大学大学院理学研究科物理学専攻 大学院講義室 理学部2号館（2－11号室）
要 旨 ：
Recent developments of multi-strange nuclear physics are overviewed, highlighting the recent experimental and theoretical developments in Lambda-Lambda hypernuclei. By applying the exact treatment of few-body (three- and four-) quantum systems, we can assess the strength of the Lambda-Lambda interactions based on the world data of Lambda-Lambda hypernuclear binding energies, including those of recently observed Lambda-Lambda-4H and Lambda-Lambda-6He nuclei. The most clear event (Lambda-Lambda-6He) supports a one-boson-exchange soft core model (NSC97), and Faddeev calculations using the same interaction further suggest that Lambda-Xi-6He marks the onset of nuclear stability for Xi hyperons or the S = -3 world.
世話人 大西 明
ohnishi@nucl.sci.hokudai.ac.jp
北海道大学大学院理学研究科
"Physics of high Tc superconductivity: the role of spin and charge excitations (spinons and holons)"
Sung-Ho Salk
Aug 08, 2002
講演題目： Physics of high Tc superconductivity: the role of spin and charge excitations (spinons and holons)
講 師 ： Sung-Ho Salk
(韓国ポハン大学・教授)
日 時 ： 平成14年08月08日 (木) 14:00-
場 所 ： 北海道大学大学院理学研究科物理学専攻 大学院講義室 理学部2号館（2－11号室）
要 旨 ：
High Tc superconductivity is one of the most challenging subjects incondensed matter physics for both fundamentals and applications. In the area of its basics one of the most searched subjects is the mechanism of superconductivity for doped cuprates, which still remains to be resolved. First, multifaceted aspects of experimental observations will be briefly reviewed. They are the ARPES, STM, muSR, NMR, NQR, INS, optical concuctivity measurements and specific heat measurements. Based on these observations we then make a judicious review of various proposed theories by paying attention to the charge and spin degrees of freedom. These theories include the original RVB theory, slave-boson theories of U(1) and SU(2), SO(5), DDW, CDW and numerical simulations. We then introduce our theory of slave-boson theory which differs from the earlier ones developed by other researchers especially in the treatment of Heisenbeg term. By paying a rigorous attention to the spin and charge degrees of freedom we explain the physics of why this new theory predicts well in agreement with numerous observations, including the muSR measurements of superfluid weight vs. Tc and specific heat measurements. Time permitting we will also discuss the vortex binding-unbinding transition at low temperatures in the underdoped region.
世話人 小田 研
moda@sci.hokudai.ac.jp
北海道大学大学院理学研究科
"Hadronic and Quark/Gluon Degrees of Freedom in Hadron Interactions"
Prof. Earle L. Lomon
Nov 16, 1999
講演題目： Hadronic and Quark/Gluon Degrees of Freedom in Hadron Interactions
講 師 ： Prof. Earle L. Lomon
(Department of Physics, Massachusetts Institute of Technology, U.S.A.)
日 時 ： 平成11年11月16日 (火) 16:00-17:00
場 所 ： 北海道大学理学部２号館大学院講義室（2-2-11）
要 旨 ：
The success of Quantum Chromodynamics (QCD) in its perturbative,high momentum transfer regime, leads to the expectation that it is thegeneral theory for the strong interaction of hadrons. But the direct, lattice QCD, calculations of non-perturbative multi-hadron reactions are not now feasible. I will describe a model for QCD which incorporates its critical features of asymptotic freedom with quark and gluon degrees of freedom at short range, and confinement to hadron degrees of freedom at long range. In this hybrid model the inner and outer regions are connected by a boundary condition determined by R-Matrix theory, enabling the description of the transition from confinement to asymptotic freedom. A consequence is the prediction of exotic multi-quark state resonances, whose position and width are mainly determined by perturbative QCD with gluon exchange, but are coupled to the continuum and molecular resonances by the long range hadron exchange forces. Observable consequences in the baryon-baryon (S=0,－1 and－2), and meson-baryon (S=1) sectors will be described and compared with available data. Ways to improve the accuracy and realism of the model will be described.
世話人 原田稔
（mharada@res.otaru-uc.ac.jp）
小樽商科大学一般教育
"Probing the Energy Gap of High Temperature Superconductors with Tunneling Spectroscopy: Evidence for Exotic Pairing"
Prof. John Zasadzinski
Oct 21, 1999
講演題目： Probing the Energy Gap of High Temperature Superconductors with Tunneling Spectroscopy: Evidence for Exotic Pairing
講 師 ： Prof. John Zasadzinski
(Illinois Institute of Technology and Argonne National Laboratory)
日 時 ： 平成11年10月21日 (木) 16:30-17:00
場 所 ： 北海道大学理学部２号館大学院講義室（2-2-11）
要 旨 ：
TTunneling spectroscopy is presented for a variety of high temperature superconducting cuprates. The data for electron doped compounds such as Nd-Ce-Cu-O which have a relatively low Tc = 22K are consistent with an s-wave energy gap and ordinary phonon mediated pairing. However, the tunneling data for hole-doped cuprates such as Bi-Sr-Ca-Cu-O (Bi2212) with an optimal Tc = 95 K are more consistent with a d-wave energy gap. The doping dependence of the energy gap parameter in Bi2212 is anomalous, increasing to very large values in the underdoped regime even as Tc decreases. This gap parameter follows the trend of the antiferromagnetic exchange energy, J, which indicates that the pairing is of magnetic origin. The high bias tunneling spectra reveal a dip feature that is often quite pronounced and may be related to the resonance peak in the magnetic excitations probed by neutron scattering. Also, the high bias features include a secondary peak which might be an indication of a competing pseudogap of magnetic origin.
小田研 （北海道大学大学院理学研究科）
（moda@sci.hokudai.ac.jp）
"Dissipative Quantum Brain Dynamics"
Prof. Giuseppe Vitiello
Jun 02, 1999
講演題目： Dissipative Quantum Brain Dynamics
講 師 ： Prof. Giuseppe Vitiello
(Dipartimento di Fisica, Universita' di Salerno, Italy)
日 時 ： 平成11年6月2日 (水) 16:30-17:30
場 所 ： 北海道大学理学部２号館大学院講義室（2-2-11）
要 旨 ：
The quantum model of brain has been extended to dissipative dynamics in order to solve the problem of memory capacity. This gave rise to an interesting framework to study consciousness related mechanisms. The brain is modeled as an open system interacting with the environment and the information storage is represented through the dynamical generation of collective modes under external stimuli. We find different life-times for modes of different momentum. This suggests interesting features related with memory persistence time. Also stimulated by the increasing interest in quantum features of neural net dynamics, either in connection with information processing in biological systems, or in relation with a computational strategy based on the system quantum evolution (quantum computation), we study the classical limit of the dissipative quantum brain dynamics in order to exhibit a link with neural net dynamics.
世話人 石川健三
（ishikawa@particle.sci.hokudai.ac.jp）
北海道大学大学院理学研究科
