セミナー 2016年

Takahiro Terada, KIAS

Non-thermal Gravitino Production after Large-Field Inflation

Meeting room 1, Kenkyu honkan 1F
Gravitino abundance is a crucially important quantity in cosmology with supersymmetry. We revisit non-thermal gravitino production after inflation in supergravity paying particular attention to inflation models with a stabilizer field, in which gravitino production by preheating has not been studied. This analysis is particularly important for Z_2 symmetric large-field models, to which perturbative analyses in the literature are not applicable. We find that the transverse gravitino abundance, which is the dominant component in the case without a stabilizer field, is much suppressed in the case with a stabilizer field. The case of the inflaton potential quartic around the minimum without the stabilizer field predicts too many gravitinos, while the cases of the quadratic potential or with a stabilizer field predicts non-thermal gravitino abundance less than the thermal contribution.

Satoshi Shirai, Kavli IPMU

Search for wino dark matter

Meeting room 3, Kenkyu honkan 1F
Wino is one of the most attractive candidates for the dark matter. I will talk about characteristic signatures of the wino at the colliders and in the sky, and discuss the possibility of further improvement of the wino search.

Shigehiro Yasui, Tokyo Institute of Technology

Kondo effects in nuclear and quark matter

Meeting room 1, Kenkyu honkan 1F
The Kondo effect is a well-known phenomena that there is an enhancement of the electric resistance of electrons in metal containing impurity atoms with finite spin at low temperature. The conditions of the emergence of the Kondo effect are summarized as (i) Fermi surface (degenerate state) (ii) loop effect (particle-hole creation) and (iii) non-Abelian interaction. Those conditions can be satisfied for nuclear matter and quark matter where heavy hadrons and quarks are contained as immunity particles in the medium. In this presentation, I will introduce the recent studies of the Kondo effects in nuclear matter and quark matter, whose results may be studied in experiments in J-PARC, GSI-FAIR, NICA as well as in RHIC and LHC.

Gokce Basar, University of Maryland

Resurgence theory and quantum geometry

Meeting room 3, Kenkyu honkan 1F
The theory of resurgence connects non-perturbative physics (such as instantons) to perturbative physics in a highly nontrivial way. In this talk I will concentrate on certain quantum mechanical examples where the connection can be made precise and demonstrate how the non-perturbative data can actually be decoded from the perturbative expansion. Furthermore, I will provide a geometric explanation for this relation in terms of quantization of elliptic curves. Notably, the quantum systems I will talk about are related to supersymmetric gauge theories in the Nekrasov-Shatashvili limit.

Daniel Sudarsky, Universidad Nacional Autonoma de Mexico

Emergence of the seeds of cosmic structure during inflaton: Foundational issues in quantum theory and a search for novel aspects of physics.

Seminar room, Kenkyu honkan 3F
The observations of the first traces of cosmic structure in the Cosmic Microwave Background are in excellent agreement with the predictions of inflation. However as we shall see, that account is not fully satisfactory, as it does not address the transition from an homogeneous and isotropic early stage to a latter one lacking those symmetries. We will argue that new physics is needed to account for such transition and that some of the proposals designed to deal with the measurement problem in quantum mechanics have the required features to play that role. We will explain how observations can be used to constrain the phenomenological proposals made in this regard.

Loriano Bonora, SISSA

Why highers spins: because they are everywhere

Meeting room 3, Kenkyu honkan 1F
Higher spin theories have been regarded so far as an interesting but somewhat exotic topic in theoretical physics. I would like to show in this talk that higher spins fields appear naturally in any field theory and are more familiar to us than naively expected. I will consider free scalar and fermion theories in various dimensions (3,4,5,6) coupled to external sources with various spins and show by computing the one-loop two-point correlators that such simple models know about the (linearized classical) dynamics of these sources. The next step consists in studying the three-point functions i.e. the interaction and see whether there exist consistent solutions by comparing interactions and symmetries. This research is motivated by the quest for consistent theories with infinite many fields.

Masato Taki, RIKEN

5d gauge theory descriptions of 6d SCFTs via brane-webs

Meeting room 3, Kenkyu honkan 1F
After explaining basic background materials, I will introduce a new IIB 5-brane description for the 6d E-string theory that is the world-volume theory on M5-brane probing the end of the world M9-brane. The E-string in our new realization, which is named Tao web, is depicted as spiral 5-branes web equipped with the cyclic structure which is a key to uplifting to 6 dimensions. Utilizing the topological vertex to the 5-brane web configuration enables us to write down a combinatorial formula for the generating function of the E-string elliptic genera. Our Tao web description can be generalized to a wide range of 6d non-Lagrangian SCFTs. In the latter part of this seminar I will show many examples of brane-webs which lead to 6d SCFTs in the strongly-coupled region

Hiroshi Suzuki, Kyushu U

Fermion number anomaly with the fluffy mirror fermion

Meeting room 1, Kenkyu honkan 1F
Recently, Grabowska and Kaplan presented a 4-dimensional lattice formulation of chiral gauge theories on the basis of the so-called chiral overlap operator. We study this formulation from the perspective of the fermion number anomaly and possible associated phenomenology. A simple argument shows that the consistency of the formulation implies that the fermion with the opposite chirality to the physical one, the “fluffy mirror fermion’” or `”fluff”, suffers from the fermion number anomaly in the same magnitude (with the opposite sign) as the physical fermion. This immediately shows that if at least one of the fluff quarks is massless, the formulation provides a simple solution to the strong CP problem. Also, if the fluff interacts with gravity essentially in the same way as the physical fermion, the formulation can realize the asymmetric dark matter scenario.
(Refernece) arXiv:1608.02217

Yusuke Kimura, YITP, Kyoto University

Discrete Gauge Symmetries in F-theory Compactifications without Section (in Japanese)

Meeting room 3, Kenkyu honkan 1F
セクションを持たないF理論のモデルを考察する。セクションを持たないF理論のモデルにおいては、離散ゲージ群が自然に現れ。セクションを持たないF理論のモデルの構成や、現れる離散ゲージ群について議論する。射影空間の積における超曲面や完全交叉、および射影空間の積の2重被覆を考えることで、genus-1ファイバーを持ったセクションのないカラビ・ヤウ4-foldsを構成する。Jacobian fibrationsやそのMordell-Weil群についても議論する。また、7ブレーン上の非可換ゲージ対称性についても議論する。

Richard Ruiz, Durham U., IPPP

Neutrino Jets from High-Mass WR Gauge Bosons in TeV-Scale Left-Right Symmetric Models

Meeting room 1, Kenkyu honkan 1F,
In this seminar, we re-examine the discovery potential at hadron colliders of high-mass WR gauge bosons in Left-Right Symmetric Models. We focus on the case where the WR is very heavy compared to the heavy Majorana neutrino N. Present search strategies for WR-N production are not sensitive to this regime due to the breakdown of the collider signature definition: since the neutrinos produced in WR decays are highly boosted, their decays to leptons and jets are highly collimated, forming a single object we call a “neutrino jet.”
After exploring the phenomenology of neutrino jets, we consider an alternative WR-N search strategy at hadron colliders. We include QCD corrections to WR production with threshold resummation at NNLL and matched, for the first time, to the threshold-improved parton distributions. We these improvements, we present the discovery potential of neutrino jets  at the 13 TeV Large Hadron Collider and a hypothetical future 100 TeV Very Large Hadron Collider.
1607.03504, 1610.08985

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