大阪市立大学数理物理研究室

セミナー情報（2021年度)

日時 : 2021年11月12日(金) 10:00～
場所 : Zoom
題目 : Monopole bubbling and BPS 't Hooft operators in three, four, and five dimensions
講演者 : 吉田　豊氏（東京大）

概要 :

We evaluate the vacuum expectation values of half-BPS 't Hooft operators in supersymmetric gauge theories with eight supercharges in three, four, and five dimensions in terms of supersymmetric localization. In localization formulas, there exist non-perturbative contributions from the moduli of Dirac monopoles screened by 't Hooft-Polyakov monopoles, called monopole bubbling effects (a.k.a. monopole screening effects). By introducing orientifolds, we generalize the brane construction of monopole bubbling effects for SU(N) gauge theories to SO(N) and USp(N) gauge theories.

日時 : 2021年10月29日(金) 10:00～
場所 : Zoom
題目 : Constructing Massive Scattering Amplitudes for Electroweak Effective Field Theory
講演者 : 北原　鉄平氏（名古屋大）

概要 :

Usual calculation for quantum field theory relies on Lagrangian under a certain symmetry. Then, one can obtain amplitudes by taking Feynman rules and diagrams. In contrast, a method called ''scattering amplitudes'' (also called on-shell amplitudes, modern amplitude method, or spinor-helicity formalism) directly provides the amplitudes from symmetries without relying on Lagrangian. For example, calculations of gluon n-point scattering amplitudes can be greatly reduced in this method. This approach is expected to extract some essences in quantum field theory, which are not obvious in the usual Feynman methods. Basically, conventional scattering amplitudes are methods for the massless theory. From 2017, this method has been generalized to involve any-spin massive particles by Nima Arkani-Hamed group. In this talk, first, I will provide a brief review of the massless and massive scattering amplitudes. Next, I will introduce the scattering amplitude calculations connected with electroweak symmetry breaking, which are related to masses, vev, and longitudinal waves. In particular, we do not use the standard model Lagrangian. We derived (strictly speaking, we re-derived) several equations for electroweak symmetry breaking that are supposed to be inherent in field theory. Also, in such a bottom-up approach, we present the systematic derivation of independent three-point and four-point contact terms. This talk is based on arXiv:1909.10551 and arXiv:2008.09652.

日時 : 2021年9月9日(木) 9:00～
場所 : Zoom
題目 : M2-branes and discrete Painleve systems
講演者 : 野坂朋生氏（SISSA）

概要 :

It is known that the generating function of the partition function of the ABJM theory, the 3d Chern-Simons matter theory on N M2-branes probing C^4/Z_k orbifold background, enjoys a non-linear difference relation called the q-deformed Painleve III equation. We found that a similar relation holds also when the theory is deformed by the mass terms of the matter fields. The mass deformed ABJM theory is conjectured to exhibit a large N phase transition where the standard large N expansion formula for the massless case breaks down. The q-difference relation we found might be a useful tool to approach the phase transition in the future research. Based on the idea of Painleve/gauge correspondence and the conjectured relation between the five dimensional Yang-Mills theories and the quantization of algebraic curves, it is further suggested that the same non-linear relation is also enjoyed by the theories of M2-branes placed on more general backgrounds. As an example I will also comment on the relation between the four node circular quiver Chern-Simons matter theory and the q-deformed Painleve VI equations.

日時 : 2021年8月5日(木) 10:00～
場所 : Zoom
題目 : Non-Local extension of the Standard Model
講演者 : 岡田宣親氏（アラバマ大）

概要 :

In this talk, I will discuss a non-local extension of quantum field theory with an infinite series of derivatives in the kinetic terms of the fields. I will show that this modification provides us withinteresting phenomenology once applied to the Standard Model of particle physics.

日時 : 2021年7月1日(木) 10:00～
場所 : Zoom
題目 : Swampland conjectures and gravitational positivity
講演者 : 野海俊文氏 (神戸大学)

概要 :

The goal of the Swampland program is to identify consistency conditions for a gravitational effective theory to have a consistent UV completion and clarify their phenomenological implications toward quantum gravity phenomenology. In the first half of the talk, I will provide an introduction to the Swampland program, especially focusing on the so-called Weak Gravity Conjecture. In the latter half, I will introduce our recent attempts toward its derivation based on consistency of scattering amplitudes.

日時 : 2021年5月13日(木) 10:00～
場所 : Zoom
題目 : Peculiar relations between Argyres-Douglas theories and Lagrangian theories
講演者 : 西中崇博氏 (大阪市立大学)

概要 :

Argyres-Douglas（AD）理論はあるクラスの4次元N=2共形場理論の総称で、弱結合極限を持たないため通常の手法では解析できず、その性質の多くは謎に包まれている。しかし近年の研究により、AD理論と通常のゲージ理論の間に非自明な関係があることが明らかになっている。この関係の詳細が分かれば、通常のゲージ理論の知識を用いてAD理論の物理を解明することができるかもしれない。このトークでは、ゲージ化されたAD理論と通常のゲージ理論の新しい関係について、超共形指数とネクラソフ分配関数の観点から議論する。