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Information Center for Mathematical Science

세미나

Information Center for Mathematical Science

세미나

서울대학교 지구환경과학부 세미나

Our planet came to what we know it today through a series of geological events over its history. Much of the information about the planet’s physical and chemical evolution had been lost along the process. In this talk, I will discuss recent high-pressure mineral physics results to reveal a number of physical and chemical properties of candidate deep-mantle and core materials to help us better understand its evolution and dynamic processes. The use of a high-pressure diamond anvil coupled with synchrotron X-ray and “pump-and-probe” laser spectroscopic techniques provides exciting opportunities to directly measure properties of deep earth materials at relevant pressure-temperature conditions of the planet. Specifically, I will show how iron spin and valence states drastically affect our understanding of thermal transport and chemical evolution, how single-crystal elasticity of candidate minerals is used to build an internally-consistent mineralogical and geotherm model, how thermal transport properties of iron are used to constrain the heat flow across the core-mantle boundary and the thermal and chemical energy sources to power the Earth's geodynamo to generate magnetic fields.

한국천문연구원 콜로퀴움

인공지능을 여러 분야에 접목한 사례와 실제적인 고민들에 대해서 논의한다. 분류부터 객체 검출, 영역 분할, 이상징후 감지, 시뮬레이션 최적 문제를 풀기 위한 모델을 알아보고, 인공지능 모델을 학습하기 위한 데이터셋 구축, 모델 학습 및 구동 환경에 대해서도 간단히 소개한다.

한국천문연구원 콜로퀴움

With unprecedented angular resolution of 0.02" of ALMA, we have resolved the disk and jet system in the young protostellar system HH 212 in Orion. The disk is resolved for the first time in the vertical direction, showing a dark lane sandwiched between two bright features, appearing as a hamburger. The disk is flared as expected for an accretion disk. A highly collimated jet is also detected ejecting from the disk, consisting of a train of fast-moving bullets. It is resolved, showing a rotation across the jet axis. Thus, our ALMA observations show that a hungry baby star is spitting a chain of spinning bullets when eating a space hamburger. I will also report the detection of prebiotic complex organic molecules in the disk atmosphere and discuss their possible formation on icy grains.

서울대학교 화학과 세미나

We will present our recent efforts in the polymerization of unconventional monomers to prepare novel polymeric and nanocomposite materials. We will discuss the polymerization of a novel class of polymer-nanoparticle hybrid materials on dipolar cobalt nanoparticles, which were used as “colloidal monomers” in a process termed Colloidal Polymerization. From this process, we have been able to synthesize electroactive cobalt oxide nanowires and heterostructured nanocomposites with either noble metal, or semiconductor inclusions. We will also present our recent work on novel sulfur utilization chemistry for polymeric materials. Elemental sulfur is manufactured at a level of 70 million tons every year, which is primarily produced via hydrodesulfurization of crude petroleum. These types of polymeric materials exhibit very high charge capacity again Li-insertion and have tremendous potential as inexpensive, high performance cathodes for Li-S batteries. Furthermore, these sulfur-rich copolymers exhibit unusually high refractive indices (n = 2.0) and can be easily processed in thin films, or molded objects.

서울대학교 화학과 세미나

KAIST 화학과 세미나

Generating, transferring, and storing multiple electrons from single photons could prove revolutionary for solar energy technologies. One promising process, singlet fission (SF), produces two excited electrons from a single photon.1 This approach could be useful to overcome the theoretical solar cell’s efficiency (Shockley-Queisser limit) and create highly efficient solar cells by reducing thermally wasted high-energy photons. More than one electron needs to be transferred to realize the improvement of photovoltaic cells. In this talk, I will present a simulation-led strategy enacting two-electron transfer between an intramolecular singlet fission chromophore (tetracyanomethylene quinoidal bithiopehene with β,β′-solubilizing groups) and multielectron acceptor (anthraquinone).2 The thermodynamic plausibility of multielectron transfer from a double-triplet state and the absorption spectra of electron transfer (ET) products were predicted using quantum chemical simulations. These predictions are consistent with experimental observations of reduced lifetimes in time-resolved fluorescence spectroscopy, changes in transmission profile, and appearance of new absorption bands in transient absorption spectroscopy, all of which support multi-ET in the QOT2/AQ mixture. The analysis suggests 2ET is favored over 1ET by a 2.5:1 ratio.

POSTECH 물리학과 세미나

POSTECH 물리학과 세미나

서울대학교 물리천문학부 세미나

서울대학교 물리천문학부 세미나

1. Scrambling, quantum chaos: Out-of-time-ord​ered correlator(OTOC​), Lyapunov exponent of black hole, chaos bound 2. Maximally chaotic models: Evaluation of Lyapunov exponent in SYK model, Jackiw-Teitelbo​im model, (tensor model) 3. Spectral form factor(SFF): SFF of random matrix, SYK model and 2D CFTs.

서울대학교 물리천문학부 세미나

split supersymmetry explains the observed Higgs mass and evades stringent constraints, while keeps good features of TeV-scale supersymmetry other than the little hierarchy problem. Such scenarios naturally predict thermal wino dark matter whose mass is around 3 TeV. Its non-perturbativ​ely enhanced annihilation is a promising target of indirect detection experiments. It is known that identifying the smallest halos is essential for reducing an uncertainty in interpreting indirect detection experiments. Despite its importance, the smallest halos of thermal wino dark matter have not been well understood. In this talk, we remark two aspects: 1) neutral wino is in kinetic equilibrium with primordial plasma predominantly through inelastic processes involving slightly heavier charged wino; and 2) the resultant density contrast shows larger powers at dark acoustic oscillation peaks than in cold dark matter, which is known as an overshooting phenomenon. The latter can enhance a total luminosity of dark matter annihilation in a halo significantly.

서울대학교 물리천문학부 세미나

I will talk about two distinct ideas connected by the introduction in particle phenomenology of disordered systems with a large number of degrees of freedom. First I will show how freeze-in dark matter can solve the hierarchy problem. Then I will discuss how hidden sectors with a large number of new particles can hide at colliders.

한국고등과학원 세미나

The precise study of the Higgs boson properties ? in particular its mass and couplings ? is of the utmost importance for the investigation of BSM models with extended Higgs sectors. As New Physics currently seems to be driven to higher scales by experimental searches, the framework of Effective Field Theory is becoming necessary to address the large mass hierarchies that appear in calculations. In this context, there is a growing interest for the precise matching of Higgs couplings, and its automation. I will present recent work [1] on the matching of renormalisable couplings ? in particular scalar quartic and Yukawa couplings ? between generic theories at one-loop order. I will first show how to avoid a potential loss of accuracy in the automated calculation of threshold corrections due to large logarithmic terms in both the low- and high-energy parts of the corresponding matching conditions. Then, I will discuss different possible choices of renormalisation schemes and procedures that can potentially simplify the matching, focusing in particular on the treatment of mixing between scalars. Finally, I show some examples of results, with a comparison of different schemes in a toy model, and expressions for the one-loop matching of the Higgs quartic coupling in Supersymmetric models with Dirac gauginos.

2019 KAIST Physics Seminar

연세대학교 수학과 세미나

연세대학교 수학과 세미나

연세대학교 수학과 세미나

연세대학교 수학과 세미나

연세대학교 수학과 세미나

연세대학교 수학과 세미나
  • Title : Fock-Sobolev Spaces
  • Speaker : 조홍래
  • Data : 2019-01-07 15:00:00
  • Host : 연세대학교
  • Place :