Journal Club Information

Date: | Mar.28, 2016 (Mon) |

Room: | No.13 |

Speaker: | Asanuma/Katayama/Sakurai |

Title: | Monopoles in the Higgs phase/
Magnetic Monopoles in Unified Theories/ Static Properties of Nucleons in the Skyrme Model |

Monopoles in the Higgs phase

(Phys.Rev. D69 (2004) 065003)

Magnetic Monopoles in Unified Theories

(Nucl.Phys. B79 (1974) 276-284 )

Static Properties of Nucleons in the Skyrme Model

(Nucl.Phys. B228 (1983) 552)

PDF(Katayama)

Date: | Dec.4, 2015 (Fri) |

Room: | E316/317 |

Speaker: | Masato Arai |

Title: |
Cohomogeneity one special lagrangian submanifolds in the cotangent bundle of the sphere
(K. Hashimoto, T. Sakai) |

Special lagrangian submanifolds (SLSs) play an important role in particle physics, for example, to understand the mirror symmetry in string theory and moduli space in topological solitons in field theory. Nevertheless, no many non-trivial examples are known. In this paper, they develop a way to construct the SLS by using the so-called moment map and apply it to the cotangent bundle over the sphere. I will try to explain their method so that physicist can understand since this paper is of mathematics. After introduction of their method, I will show an example of the SLS of the cotangent bundle over the sphere.

Tohoku Math. J. 64 No. 1 (2012) 14

Date: | Nov.20, 2015 (Fri) |

Room: | E316/317 |

Speaker: | Ryusuke Endo |

Title: |
A way to discover Maxwell's equations
(Krzysztof Rebilas) |

Historically, the special relativity was found after Maxwell's equations had been established. Logically, however, we do not need Maxwell's equations as the basis for the special relativity. (For example, see Mirmin's work "Relativity without light".) Thus, the alternative history was also possible: Maxwell's equations were discoverd after the special relativity had been established. I will introduce a work along this line. We only assume (1) the static Coulomb's force law and (2) the special relativity, then we can define the electirc field and the magnetic field and deduce that those fields satisfy Maxwell's equations.

Date: | Nov.6, 2015 (Fri) |

Room: | E316/317 |

Speaker: | Filip Blaschke |

Title: |
Adiabatic Invariance of Oscillons/I-balls. (Masahiro Kawasaki, Fuminobu Takahashi and Naoyuki Takeda) |

The goal of this talk is to introduce the notion of oscillons and their significance in physics. Oscillons are long-living, time-dependent solutions of scalar field theories. Like solitons they are spatially localised objects, typically spherically symmetric, with most of the energy concentrated inside certain radius. Within this radius the field oscillates rapidly (hence the name). Unlike topological solitons or Q- kinks, their stability (or longevity) is not guaranteed by conservation of topological or global charges. Instead, it can be shown that if the mass term in the potential dominates over self-interaction part, the so- called adiabatic charge is approximately (or in some models exactly) conserved. It is believed that oscillons may play significant role in Early Universe cosmology, in particular inflation and baryogenesis, as these phenomena are govern by real scalar field(s).

arXiv:1508.01028v1

PDF Keynote

Date: | Oct.16, 2015 (Fri) |

Room: | E316/317 |

Speaker: | Minoru Eto |

Title: |
Scattering of Nucleons in the Classical Skyrme Model
(David Foster, Nicholas S. Manton) |

Classically spinning B=1 Skyrmions can be regarded as approximations to nucleons with quantised spin. Here, we investigate nucleon-nucleon scattering through numerical collisions of spinning Skyrmions. We identify the dineutron/diproton and dibaryon short-lived resonance states, and also the stable deuteron state. Our simulations lead to predictions for the polarisation states occurring in right angle scattering.

http://arxiv.org/abs/1505.06843

Date: | Oct.2, 2015 (Fri) |

Room: | E316/317 |

Speaker: | Teijiro Saito |

Title: | Gauge Freedom in Path Integrals in Abelian Gauge Theory |

Starting from the Faddeev-Popov path integral in the Landau gauge formalism in Abelian guage theory, we extended the gauge symmetry to incorporate quantum gauge degrees of freedom. Specifically, we apply two Harada-Tsutsui extensions to recover the gauge symmetry in gauge non-invariant actions; (i) we introduce an additional field as a gauge degree of freedom of the extended gauge symmetry, and (ii) we gauge-fix the extended gauge symmetry by the usual Faddeev-Popov procedure. The first extension yields the theory of Type I gaugeon formalism. The second extension leads to a theory that is equivalent to the extended Type I gaugeon formalism.

Date: | July 24, 2015 (Fri) |

Room: | E316/317 |

Speaker: | Satomi Okada |

Title: |
Higgs Inflation, Seesaw Physics and Fermion Dark Matter
(Nobuchika Okada, Qaisar Shafi) |

We present an inflationary model in which the Standard Model Higgs doublet field with non-minimal coupling to gravity drives inflation, and the effective Higgs potential is stabilized by new physics which includes a dark matter particle and right-handed neutrinos for the seesaw mechanism. All of the new particles are fermions, so that the Higgs doublet is the unique inflaton candidate. With central values for the masses of the top quark and the Higgs boson, the renormalization group improved Higgs potential is employed to yield the scalar spectral index ns?0.968, the tensor-to-scalar ratio r?0.003, and the running of the spectral index α=dns/dlnk??5.2×10?4 for the number of e-folds N0=60 (ns?0.962, r?0.004, and α??7.5×10?4 for N0=50). The fairly low value of r?0.003 predicted in this class of models means that the ongoing space and land based experiments are not expected to observe gravity waves generated during inflation.

arXiv:1501.05375

Date: | July 3, 2015 (Fri) |

Room: | E316/317 |

Speaker: | Yosihide Murakami |

Title: |
Color magnetism in non-Abelian vortex matter
(M. Kobayashi, E. Nakano, M. Nitta) |

We propose color magnetism as a generalization of the ordinary Heisenberg (anti-)ferro magnets on a triangular lattice. Vortex matter consisting of an Abrikosov lattice of non-Abelian vortices with color magnetic fluxes shows a color ferro or anti-ferro magnetism, depending on the interaction among the vortex sites. A prime example is a non- Abelian vortex lattice in rotating dense quark matter, showing a color ferromagnetism. We show that the low-energy effective theory for the vortex lattice system in the color ferromagnetic phase is described by a 3+1 dimensional CP(N－1) nonlinear sigma model with spatially anisotropic couplings. We identify gapless excitations independent from Tkachenko modes as color magnons, that is, Nambu-Goldstone modes propagating in the vortex lattice with an anisotropic linear dispersion relation. We calculate the transition temperature between the ordered and disordered phases, and apply it to dense quark matter.

arXiv:1311.2399v2

Date: | June 19, 2015 (Fri) |

Room: | E316/317 |

Speaker: | Minoru Eto |

Title: |
Aloof Baby Skyrmions
(Petja Salmi, Paul Sutcliffe) |

We show that a suitable choice for the potential term in the two- dimensional baby Skyrme model yields solitons that have a short-range repulsion and a long-range attraction. The solitons are therefore aloof, in the sense that static multi-soliton bound states have constituents that preserve their individual identities and are sufficiently far apart that tail interactions yield small binding energies. The static multi-soliton solutions are found to have a cluster structure that is reproduced by a simple binary species particle model. In the standard three-dimensional Skyrme model of nuclei, solitons are too tightly bound and are often too symmetric, due to symmetry enhancement as solitons coalesce to form bound states. The aloof baby Skyrmion results endorse a way to resolve these issues and provides motivation for a detailed study of the related three-dimensional version of the Skyrme model.

http://arxiv.org/abs/1409.8176

Date: | June 5, 2015 (Fri) |

Room: | E316/317 |

Speaker: | Ryusuke Endo |

Title: | Finite field-dependent BRST transformations |

The Becci-Rouet-Stora-Tyutin (BRST) transformation has become a baisc tool for studying quantum gauge theories. The BRST transformaiton is a kind of infenitesimal gauge transformations, under which the gauge-fixed quantum Lagrangian is still invariant. The peculiar feature of the transformation is that the transformation parameter should be Grassmann numbers (anti-commuting c-numbers), and thus the corresponding Noether charge is fermionic. Joglekar and Mandal extended the BRST transformaiotn. They treated the transformaiton parameters to be finite and field- dependent. Although the Lagrangian is still invariant under this finite field- dependent BRST (FFBRST) transformations, the path integral measure is no longer invariant due to the field-depencence of the parameters. By choosing a special FFBRST transformation, the path integral Jacobian can be regarded as an additional term to the Lagarangian. The Lagrangians of the different gauges (ex. Landau gauge and Feynman gauge) can be connected by these additional terms. After reviewing the usual BRST transformations (for the MC students), I will briefly introduce the FFBRST transfomation of Joglekar and Mandal with some applications.

Date: | Apr.6, 2015 (Fri) |

Room: | S402 |

Speaker: | Masato Arai |

Title: | Introduction to gauge-Higgs unification 2 |

The Higgs particles in the Standard Model play an important role. For instance, they are source of masses of the matters and give rise to the electroweak symmetry breaking. On the other hand they lead to the theoretical problems such as huge quantum corrections and the hierarchy problem. To solve these problems, a theory without Higgs particles is proposed in the extra-dimensional theory over than 20 years ago. Since that the theory has been developing and nowadays this is called a gauge-Higgs unification. In this journal club I would like to introduce the basics of this theory.