Hajime Fukuda, Kavli IPMU
How can we solve the strong CP problem
Meeting room 1, Kenkyu honkan 1F
The strong CP problem is one of the long-standing problems in the Standard Model. I will first review the strong CP problem and the solutions proposed so far. Then, among these solutions, I will focus on the Peccei-Quinn mechanism. However, the quality, why it is a good “symmetry”, is highly mysterious. Based on our recent works, I will discuss models realizing a good symmetry.
Junichi Sakamoto, Kyoto University
T-folds from Yang-Baxter deformations (in Japanese)
Meeting room 1, Kenkyu honkan 1F Yang-Baxter (YB) deformations of type IIB string theory have been well studied from the viewpoint of classical integrability.
Yang-Baxter (YB) deformations of type IIB string theory have been well studied from the viewpoint of classical integrability.
Most of the works, however, are focused upon the local structure of the deformed geometries and the global structure still remains unclear.
In this talk, we reveal a non-geometric aspect of YB-deformed backgrounds as T-fold by explicitly showing the associated O(D,D; Z) T-duality monodromy.
In particular, the appearance of an extra vector field in the generalized supergravity equations (GSE) leads to the non-geometric Q-flux.
In addition, we study a particular solution of GSE that is obtained by a non-Abelian T-duality
but cannot be expressed as a homogeneous YB deformation, and show that it can also be regarded as a T-fold.
This result indicates that solutions of GSE should be non-geometric quite in general beyond the YB deformation.
Jonna Koponen, INFN Roma
Light meson form factors at high Q^2 from lattice QCD
Meeting room 1, Kenkyu honkan 1F Measurements and theoretical calculations of meson form factors are essential for our understanding of internal hadron structure and QCD, the dynamics that bind the quarks in hadrons. The pion form factor has been measured at small momentum transfer (Q^2) using elastic scattering and pion electroproduction. On the other hand, in the limit of very large (or infinite) Q^2 perturbation theory is applicable. This leaves a gap in the intermediate Q^2 where the form factors are not known.
Measurements and theoretical calculations of meson form factors are essential for our understanding of internal hadron structure and QCD, the dynamics that bind the quarks in hadrons. The pion form factor has been measured at small momentum transfer (Q^2) using elastic scattering and pion electroproduction. On the other hand, in the limit of very large (or infinite) Q^2 perturbation theory is applicable. This leaves a gap in the intermediate Q^2 where the form factors are not known.
Jefferson Lab are upgrading their experiment and will measure pion and kaon form factors in this intermediate region, up to Q^2 of 6?8 GeV^2 for the pion. This is then an ideal opportunity for lattice QCD to make an accurate prediction ahead of the experimental results. Lattice QCD provides the state-of-the-art techniques to calculate form factors, and the challenge here is to control the statistical and systematic uncertainties as errors grow when going to higher Q^2 values. In this talk we report of a calculation that tests the method using an eta_s meson, a ‘heavy pion’ made of strange quarks, and also present preliminary results for kaon and pion form factors.
Yoshinori Honma, National Tsing-Hua University
On the Flux Vacua in F-theory Compactifications
Meeting room 3, Kenkyu honkan 1F, slides (kek.jp only)
We study moduli stabilization of the F-theory compactified on an elliptically fibered Calabi-Yau fourfold. Our setup is based on the mirror symmetry framework including brane deformations. The complex structure moduli dependence of the resulting 4D N=1 effective theory is determined by the associated fourfold period integrals. By turning on appropriate G-fluxes, we explicitly demonstrate that all the complex structure moduli fields can be stabilized around the large complex structure point of the F-theory fourfold. This talk is based on a collaboration with H. Otsuka (1706.09417[hep-th]).
Yuko Urakawa, Nagoya University
Exploring string axiverse from gravitational wave background
Meeting room 1, Kenkyu honkan 1F
I will talk about our recent work with N. Kitajima and J. Soda, where we initiated a study on various cosmological imprints of string axions whose scalar potentials have plateau regions. In such cases, a delayed onset of oscillation generically leads to a parametric resonance instability. We show that a sustainable resonance can lead to a turbulence phase during which detectable gravitational waves by pulsar timing arrays can be emitted.
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
