押川正毅, 東京大学
[第五回KEK連携コロキウム] ベレジンスキー・コステリッツ・サウレス転移とハルデン現象 ２０１６年ノーベル物理学賞の奇妙な背景
つくばキャンパス研究本館小林ホール/東海キャンパス東海1号館324室 (TV会議中継) ２０１６年のノーベル物理学賞は、「トポロジカル相転移と物質のトポロジカル相の理論的発見」に対して、サウレス、コステリッツ、ハルデンの三氏に授与された。
２０１６年のノーベル物理学賞は、「トポロジカル相転移と物質のトポロジカル相の理論的発見」に対して、サウレス、コステリッツ、ハルデンの三氏に授与された。
ハルデン氏の主要な受賞業績は、量子反強磁性スピン鎖の定性的な性質はスピン量子数が半奇数か整数かによって全く異なり、 整数スピンの場合には励起ギャップ（「ハルデンギャップ」）を持つという予言である。ほとんどの教科書や解説では、ハルデン氏のこの理論的発見は、素粒子論から「輸入」された有効的な場の理論である非線形シグマ模型が持つトポロジカル項に基づいたものとされてきた。
しかし、ハルデン氏本人の回顧や、失われていた「幻の論文」の発見によって、ハルデン氏による当初の発見の経緯はそれとは大きく異なり、同時にノーベル物理学賞の授賞対象となったベレジンスキー・コステリッツ・サウレス（BKT）転移の理論と密接に関係していたことが明らかになった。
本講演では、おそらく当時としてはあまりに斬新すぎたために奇妙な運命をたどったハルデンギャップの発見の経緯とともに、その物理的内容をなるべくわかりやすく解説したい。また、ハルデンギャップの発見がその後の物理学の発展に与えた影響についても議論したい。
Gerco Onderwater, Groningen U
Lepton Anomalies @ LHCb and elsewhere
Room 345, 4 go-kan
There is a wealth of experimental results questioning the deep-rooted assumption of lepton universality in flavour-changing interactions, while at the same time the large LHC experiments, ATLAS and CMS, do not see clear signals of New Physics. Recently several flavour anomalies were reported by the LHCb collaboration and there is the long standing discrepancy of the anomalous magnetic moment of the muon. At the same time there are ever-more impressive limits on charged lepton flavour violation. A comprehensive overview of how these results were obtained will be presented and their interconnections will be highlighted.
Ryo Yoshiike, Kyoto University
Role of axial anomaly and nesting in the inhomogeneous chiral phase
Meeting room 1, Kenkyu honkan 1F
Recently inhomogeneous chiral phase (iCP) has been expected to appear in the moderate density region in the QCD phase diagram, where chiral condensate is spatially modulating. It has been known that axial anomaly and nesting play important roles for iCP. Using the Gross-Neveu models in 1+1 dimensions, we shall discuss axial anomaly and nesting from two different points of view:one is inhomogeneous chiral transition and the other is the Ferrel-Fulde-Larkin-Ovchinnikov state in superconductivity, which are closely related to each other by way of duality.
Rainer Sommer, DESY
How strong are the strong interactions
Meeting room 1, Kenkyu honkan 1F
The ALPHA Collaboration has computed one of the most elusive fundamental parameters of Nature: the strong coupling. It governs the interactions of quarks and gluons. At high energies, such as the ones reached at the Large Hadron Collider (LHC) at CERN, many processes can be computed in terms of a Taylor series in this coupling. A precise input value for these series is thus essential to make best use of the accelerator. We have “simulated” QCD, the fundamental theory of the strong interactions, over a large range of energy scales in order to extract the coupling at LHC energies. The experimental input which is presently best suited to minimize the total uncertainty is, surprisingly, the weak decay rate of Pions and Kaons. We explain how our work sets a new standard in the determination of the strong coupling.
Takahiro Doi, Quantum Hadron Physics Laboratory, Nishina Center, RIKEN
Lattice QCD study for relation between quark-confinement and chiral symmetry breaking
Meeting room 1, Kenkyu honkan 1F
Both quark-confinement and chiral symmetry breaking are important non-perturbative phenomena in low-energy QCD. The motivation in this study is to investigate the relation between them. To that end, we derive some analytical relations between the Polyakov loop and the eigenmodes of the Dirac operator on a lattice. Those formulae suggest no direct one-to-one correspondence between quark-confinement and chiral symmtery breaking in QCD.
Yasuyuki Hatsuda, Rikkyo University
Borel resummation and S-duality in SL(2) Chern-Simons theory
Meeting room 3, Kenkyu honkan 1F
I will talk about an S-duality in SL(2) Chern-Simons theory. A perturbative semiclassical expansion does not have this symmetry, but its Borel resummation turns out to recover the exact S-dual symmetry.
Massimo Passera, INFN Padova
Measuring the leading hadronic contribution to the muon g-2 via muon-electron scattering
Seminar room, Kenkyu honkan 3F
I will present a recent proposal to determine the leading hadronic contribution to the muon g-2 via the measurement of the running of the electromagnetic coupling constant in the space-like region, by scattering high-energy muons on atomic electrons of a low-Z target.
Varun Sethi, University of Delhi
Finite Temperature Corrections to Tachyon Mass in Intersecting D-branes and Stacks of D-branes
Meeting room 1, Kenkyu honkan 1F, slides (kek.jp only)
In arXiv:1104.2843, a microscopic top-down model of a holographic superconductor is constructed using two intersecting D8-branes in the bulk in D4-brane background. This is a non-BPS configuration which has tachyons in its spectrum signaling instability of the system. This instability has been proposed to be the bulk analogue of the BCS instability in the boundary theory in 1104.2843. Our aim is to study a similar simplified system at finite temperature and evaluate the transition temperature. We thus consider a system of two intersecting D3 -branes in flat background, we compute one-loop finite temperature correction to tachyon two-point amplitude and find, numerically, the transition temperature at which effective mass-squared of the tachyon becomes zero. We further extend the calculation of tachyon two-point amplitude to the case of intersecting stacks of D3-branes.
Seiji Terashima, Yukawa Institute for Theoretical Physics
AdS/CFT Correspondence in Operator Formalism
Meeting room 3, Kenkyu honkan 1F
In this paper we study the AdS/CFT correspondence in the operator formalism without assuming the GKPW relation. We explicitly show that the low energy spectrum of the large N limit of CFT, which is realized by a strong coupling gauge theory, is identical to the spectrum of the free gravitational theory in the global AdS spacetime under some assumptions which are expected to be valid. Thus, two theories are equivalent for the low energy region under the assumptions. Using this equivalence, the bulk local field is constructed and the GKPW relation is derived.
Wen Yin, IHEP Chinese Academy of Sciences
Higgs-Anomaly Mediation: a simple setup with interesting phenomena and flavor safety
Meeting room 1, Kenkyu honkan 1F
