Ignatios Antoniadis, University of Bern
Aspects of string phenomenology and scale hierarchies
Meeting room 3, Kenkyu honkan 1F
I will discuss the problem of scale hierarchies in string phenomenology of particle physics and cosmology and propose ways to address it. In particular I will present a mechanism for supersymmetry breaking in the presence of a tiny (tunable) positive cosmological constant and describe its phenomenological consequences
Ryosuke Sato, Weizmann Inst.
Spherical symmetry of the bounce solution
Meeting room 3, Kenkyu honkan 1F
In his 1977 paper on vacuum decay in field theory: The Fate of the False Vacuum, Coleman considered the problem of a single scalar field and assumed that the minimum action tunnelling field configuration, the bounce, is invariant under O(4) rotations in Euclidean space. A proof of the O(4) invariance of the bounce was provided later by Coleman, Glaser, and Martin (CGM), who extended the proof to N > 2 Euclidean dimensions but, again, restricted non-trivially to a single scalar field. As far as we know a proof of O(N) invariance of the bounce for the tunnelling problem with multiple scalar fields has not been reported, even though it was assumed in many works since, being of phenomenological interest. We make progress towards closing this gap. Following CGM we define the reduced problem of finding a field configuration minimizing the kinetic energy at fixed potential energy. Given a solution of the reduced problem, the minimum action bounce can always be obtained from it by means of a scale transformation. We show that if a solution of the reduced problem exists, then it and the minimum action bounce derived from it are indeed O(N) symmetric.
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.
