Kai Schmitz, Kavli IPMU
Hybrid or Chaotic? The Current Status of Inflation from a Subjective Perspective
Meeting room 1. Kenkyu honkan 1F
Precise measurements of the B-mode polarization of the cosmic microwavebackground are crucial for our understanding of cosmic inflation. If upcomingobservations should confirm the large tensor signal recently reported by theBICEP2 collaboration, inflation may have simply been driven by a simplemonomial potential as employed in models of chaotic inflation. If, on the otherhand, the BICEP2 signal should disappear once the dust (polarization issue) has(been) settled, attention might shift again towards small-field models of inflationbecause of their attractive properties on the particle physics side. In this talk, Iwill discuss both scenarios for the possible fate of our understanding of cosmicinflation and present recent results on explicit models that either predict a verylarge or a very small tensor-to-scalar ratio. First, I will illustrate how stronglyinteracting supersymmetric gauge theories can give rise to inflationary dynamicsthat mimic those of chaotic inflation, cf. 1403.4536 [hep-ph]; then I will revisitsupersymmetric F-term hybrid inflation and demonstrate how a notoriouslyoverlooked feature of this model can render it consistent with all observations(except for BICEP2) after all, cf. 1404.1832 [hep-ph]).
Shun Saito, Kavli IPMU
Neutrino mass constraint from robust cosmological signals in the BOSS DR11 galaxy clustering
Meeting room 1, Kenkyu Honkan 1F In this talk I will first give a brief highlight of ~1% measurement of the cosmological distance via Baryon Acoustic Oscillation (BAO) and ~10% measurement of the growth of large-scale structure via Redshift-Space Distortion (RSD) as fairly robust cosmological signals at z~0.5 from the updated data-relrease 11 (DR11) of Baryon Oscillation Spectroscopic Survey (BOSS). BOSS is part of Sloan Digital Sky Survey III (SDSS-III), and a gigantic cosmological survey aiming at mapping 1.5 million luminous galaxies and 200,000 quasars. BOSS DR11 contains almost million galaxies over 8,500 deg^2 which is currently the best 3-dimensional map of galaxies in the universe. I will describe how to efficiently measure BAO and RSD from such a huge dataset, and discuss how useful BAO and RSD are. In particular, I will focus on the neutrino mass constraint using BOSS BAO and RSD, and discuss how the neutrino mass can resolve discrepancies among cosmological datasets at early and at late time.
In this talk I will first give a brief highlight of ~1% measurement of the cosmological distance via Baryon Acoustic Oscillation (BAO) and ~10% measurement of the growth of large-scale structure via Redshift-Space Distortion (RSD) as fairly robust cosmological signals at z~0.5 from the updated data-relrease 11 (DR11) of Baryon Oscillation Spectroscopic Survey (BOSS). BOSS is part of Sloan Digital Sky Survey III (SDSS-III), and a gigantic cosmological survey aiming at mapping 1.5 million luminous galaxies and 200,000 quasars. BOSS DR11 contains almost million galaxies over 8,500 deg^2 which is currently the best 3-dimensional map of galaxies in the universe. I will describe how to efficiently measure BAO and RSD from such a huge dataset, and discuss how useful BAO and RSD are. In particular, I will focus on the neutrino mass constraint using BOSS BAO and RSD, and discuss how the neutrino mass can resolve discrepancies among cosmological datasets at early and at late time.
Refs. http://arxiv.org/abs/1312.4611 , http://arxiv.org/abs/1403.4599
Xiang Liu, School of Physical Science and Technology, Lanzhou University
Charged charmonium-like structures and the initial single chiral particle emission mechanism
Seminar Room, Kenkyu Honkan 3F
In this talk, I will introduce how the ISPE mechanism is introduced to explain the charged bottomonium-like states Zb(10610) and Zb(10650). Later, I will illustrate the relation between the prediction of charged charmonium-like structures and the observed charged charmonium-like states Zc(3900) and Zc(4025). By the ISChE mechanism, more abundant phenomena of charged charmonium-like structures were predicted, which will be introduced in this talk.
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
