Hiromasa Takaura, Kyushu University
Determination of αs from static QCD potential with renormalon subtraction
Meeting room 1, Kenkyu honkan 1F
The strong coupling constant α_s is a fundamental parameter in the standard model and requires to be determined with higher accuracy. We determine α_s from static QCD potential with a new method where a renormalon uncertainty, which is an inevitable error in perturbative predictions, is subtracted from a theoretical prediction. We obtain α_s(M_Z^2)=0.1178+0.0016/-0.0015, which is consistent with the PDG result.
Misao Sasaki, Kavli IPMU, The University of Tokyo
Scalaron as a Heavy Field and Formation of Primordial Black Holes
Meeting room 1, Kenkyu honkan 1F, slides (kek.jp only)
We propose a model of two-stage inflation in which a scalar field, χχ, is non-minimally coupled to Starobinsky’s R2R2 gravity. The scalaron, ϕϕ, in Starobinsky’ model drives the first stage of inflation, and χχ drives the second. At the end of the first stage, the scalaron becomes heavy and undergoes damped oscillations. This causes enhancement and oscillatory features in the curvature perturbation power spectrum. The peak in these features may give rise to copious production of primordial black holes (PBHs). For a suitably chosen set of model parameters, these PBHs may even dominate the CDM of the Universe.
Chen Zhang, National Center for Theoretical Sciences, Physics Division
Simplest Little Higgs Revisited: Hidden Mass Relation, Unitarity and Naturalness
Meeting room 1, Kenkyu honkan 1F
In this talk, I will present an analysis of the scalar potential of the Simplest Little Higgs (SLH) model in an approach consistent with the spirit of continuum effective field theory (CEFT). A hidden mass relation is obtained relating the pseudo-axion mass and top partner mass, serving as a crucial test of the SLH mechanism. I also propose a strategy of analyzing the fine-tuning problem consistent with the spirit of CEFT and apply it to the SLH. The scalar potential and fine-tuning analysis strategies investigated here should also be applicable to a wide class of Little Higgs and Twin Higgs models, which may reveal interesting relations as crucial tests of the related electroweak symmetry breaking mechanism and provide a new perspective on assessing their degree of fine-tuning.
Piljin Yi, Korea Institute for Advanced Study
Witten, Cardy, and the Holonomy Saddle
Meeting room 1, Kenkyu honkan 1F
This talk will explore topological invariants of susy gauge theories, with some emphasis on index-like quantities and the notion of holonomy saddles. We start with 1d refined Witten index computations where the twisted partition functions typically show rational, rather than integral, behavior. We will explain how this oddity is a blessing in disguise and propose a universal tool for extracting the truely enumerative Witten indices. In part, this finally put to the rest a two-decade-old bound state problems which had originated from the M-theory hypothesis. Along the way, we resolve an old and critical conflict between Kac+Smilga and Staudacher/Pestun, circa 1999~2002, whereby the notion of H-saddles emerges and plays a crucial role. More importantly, H-saddles prove to be universal features of supersymmetric gauge theories when the spacetime include a small circle: H-saddles are explored further for d=4, N=1 theories, with much ramifications on some recent claims on Cardy exponents of their partition functions.
Fred Olness, Southern Methodist U
PDF flavour determination and nCTEQ PDFs:(challenges and opportunities of QCD)
Meeting room 1, Kenkyu honkan 1F
We use nCTEQ15 nPDFs with uncertainties to identify measurements whichhave a potential impact on nuclear corrections and flavor differentiation. In particular, recent LHC W/Z vector boson production data in proton-lead and lead-lead collisions are quite sensitive to heavier flavors (especially the strange PDF). This complements the information from neutrino-DIS data. As the proton flavor determination is dependent on nuclear corrections (from heavy target DIS, forexample), this information can also help improve proton PDFs.
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
