Taizan Watari, Kavli IPMU
Statistics of Low-Energy Effective Theories in F-theory Flux Compactification
Meeting room 3, Kenkyu honkan 1F Compactification of string theory gives rise to plethora of vacua, at least as long as we adopt the understanding of string theory in the last decade or so. This is usually regarded as lack of precise low-energy prediction, and certainly it is, but there is also a positive side; the landscape of vacua may be regarded as theoretical foundation for eternal inflation and also for the notion of naturalness.
Compactification of string theory gives rise to plethora of vacua, at least as long as we adopt the understanding of string theory in the last decade or so. This is usually regarded as lack of precise low-energy prediction, and certainly it is, but there is also a positive side; the landscape of vacua may be regarded as theoretical foundation for eternal inflation and also for the notion of naturalness.
It has been known well for a decade that flux compactification of F-theory / Type IIB string theory stabilizes 7-brane configuration as well as complex structure moduli of the internal geometry. This means that the statistics of gauge group and matter multiplicity of low-energy effective theories can be determined, in principle. In practice, though, not much has been done so far to make this possibility come to reality.
We begin with a question when two F-theory vacua on elliptic fibred geoemtries describe physically distinct vacua, and then move on to study how to derive statistics of gauge groups by using K3 x K3 compactification of F-theory. With F-theory compactification on more general Calabi–Yau 4-folds in mind, analytic vacuum distribution formula by Ashok-Denef-Douglas is also generalized so that the formula can be used to address various questions of phenomenological interest. As an example, we will discuss the statistics of number of generations.
This talk is based on a joint work with Andreas Braun and Yusuke Kimura.
Poghosyan Sergey, Kochi University of Technology
Quantum graph vertices with minimal number of passbands
Seminar Room, Kenkyu Honkan 3F
We study a set of scattering matrices of quantum graphs containing minimal number of pass- bands, i.e., maximal number of zero elements. The cases of even and odd vertex degree are considered. Using a solution of inverse scattering problem, we reconstruct boundary conditions of scale-invariant vertex couplings. Potential-controlled universal flat filtering properties are found for considered types of vertex couplings. Obtained boundary conditions are approximated by simple graphs carrying only δ potentials and inner magnetic field.
Shinji Shimasaki, KEK
Emergent bubbling geometries in the plane wave matrix model
Meeting room 3, Kenkyu honkan 1F
The gravity dual geometry of the plane wave matrix model is given by the bubbling geometry in the type IIA supergravity, which is described by an axially symmetric electrostatic system. We study a quarter BPS sector of the plane wave matrix model in terms of the localization method and show that this sector can be mapped to a one-dimensional interacting Fermi gas system. We find that the mean-field density of the Fermi gas can be identified with the charge density in the electrostatic system in the gravity side. We also find that the scaling limits in which the dual geometry reduces to the D2-brane or NS5-brane geometry are given as the free limit or the strongly coupled limit of the Fermi gas system, respectively. We reproduce the radii of S^5’s in these geometries by solving the Fermi gas model in the corresponding limits.
Dmitry Khangulyan, JAXA/ISAS
What happens when an AGN jet slams into a star?
Meeting room 1, Kenkyu honkan 1F
Observations of AGNs with different high energy instruments indicate on formation of gamma rays in compact regions (i.e., in blobs). This, in particular, is supported by the shapes of recorded lightcurves and by the ultra-fast variability time scales obtained with ground based Cherenkov detectors (e.g., with H.E.S.S.). However, the conventional approach for modelling of these sources features calculations of the non-thermal high-energy emission leaving the question related to the nature of these blobs less addressed. I will discuss a specific scenario for blobs in AGN jets: formation of blobs at interaction of AGN jet with a star. Despite the apparent generality, once applied to a specific source the scenario implies quite strict consequences on the properties of the jet and possible production mechanism at work. To illustrate this, I consider two exceptionally challenging cases: the ultra-fast variability detected with H.E.S.S. from the blazar PKS 2155-304, and extremely bright flare register with Fermi/LAT from 3C454.3. The scenario, if realised, can readily explain several puzzling features, like the lightcurve shapes and variability time scale, and allows to constraint the key properties of the sources. (to be updated)
Shunji Matsuura, McGill Univ.
Charged Quantum Entanglement
Meeting room 3, Kenkyu honkan 1F
Quantum entanglement has emerged as a very useful probe in high energy physics and condensed matter physics. In this talk, we will introduce a new class of entropies that measures the degree of quantum entanglement in different charge sectors. We investigate the phase structure of CFT and the topological phases by using these quantum measures.
Masazumi Honda, Harish-Chandra Research Institute
Higgs branch localization of 3d N=2 theories
Meeting room 1, Kenkyu honkan 1F
Recently there has been much progress in understanding supersymmetric field theory on curved space. In my talk, I will focus on three dimensional N=2 theories in squashed sphere and S2xS1. Recent studies observed that the partition functions in a class of the 3d N=2 theories consist of the same building blocks, which are essentially vortex parition functions. I will explain how we have directly derived this structure by a new type of localization (“Higgs branch localization”) in more wide class of theories. If I have a time, I will also discuss supersymmetric Wilson loop.
Jonathan Maltz, Kavli IPMU
[Strings and Fields Group Seminar] Gauge invariant computable quantities in time like Liouville theory
Meeting Room 3, Main Bldg. 1F
Anna Hasenfratz, University of Colorado Boulder
Strongly coupled gauge theories in and out of the conformal window
Meeting room1, Kenkyu honkan 1F
Asymptotically free gauge systems with many fermionic degrees of freedom can develop a conformal infrared fixed point. Near the conformal window these strongly coupled systems can have unusual properties, and might contain a light scalar, a composite candidate for the Higgs boson. Lattice studies are particularly suited to study these strongly coupled models, though methods developed for QCD studies are not always effective. In this talk I will give a brief overview of our understanding of these systems. I will concentrate on two rather different methods, the Dirac operator spectral density, and a variant of finite size scaling, to illustrate the unusual properties of these intriguing systems.
Yoshimasa Hidaka, RIKEN
Generalization of the Nambu-Goldstone theorem
Seminar room, Kenkyu honkan 3F
Symmetry and its spontaneous breaking are of basic importance for understanding the low energy physics in many-body systems. When a continuum symmetry is spontaneously broken, there exist a zero mode called Nambu-Goldstone (NG) mode, which is well developed in Lorentz invariant systems. In contrast, in non-Lorentz invariant systems, the NG theorem has not been well developed. In this talk, we discuss the recent progress in generalization of NG theorem, and discuss the counting rule for NG modes using the Langevin equation derived from Mori’s projection operator method. We show that the number of NG modes is equal to the number of broken charges, Qa, minus half the rank of the expectation value of [Qa,Qb]. We also discuss the spontaneous breaking of space-time symmetries.
Kin-ya Oda, Osaka U
Minimal Higgs inflation
Meeting room 1, Kenkyu honkan 1F
