Journal Club Information

1st semester

Date: | July 29, 2016 (Fri) 16:10~ |

Room: | S402 |

Speaker: | Yuki Katayama |

Title: | Neutrino masses, mixing, and oscillations |

In the standard model, there is no neutrino mass. However it was found through neutrino oscillation phenomena that neutrinos have small masses. So, we need to introduce neutrino mass terms to the standard model. There are two types of mass terms, Dirac and Majorana types. Here, I will report on a relationship between neutrino oscillations and masses, and the two type mass terms. I will also discuss that neutrino masses are limited by cosmology.

Date: | July 22, 2016 (Fri) 16:10~ |

Room: | S402 |

Speaker: | Kohei Sakurai |

Title: | Semilocal and electroweak strings |

This paper is a review of semi-local strings and electroweak strings. I will introduce the first part of this paper (chap.1-3), written about the Nielsen-Olesen strings and semi-local strings.

A.Achucarro, T.Vachaspati

Physics Reports 327(2000) 347-426

Date: | July 15, 2016 (Fri) 16:10~ |

Room: | S402 |

Speaker: | Yuji Asanuma |

Title: | All exact solutions of a 1/4 Bogomol'nyi-Prasad-Sommerfield equation |

A 1/4Bogomol'ny-Prasad-Sommerfield (BPS) equation containing configurations made of walls, vortices, and monopoles in the Higgs phase, describes physical phenomenon, such as Type Ⅱ superconductivity. We study a 1/4 BPS equation by using super symmetry(SUSY). We find the total moduli space by using "moduli matrix". In the strong coupling limit, this equation can be solved exactly. In this talk, I will explain a part process how to solve a 1/4 BPS equation.

Youichi Isozumi, Muneto Nitta, Keisuke Ohashi, and Norisuke Sakai, PHYSICAL REV D71,065018 (2005);

David Tong , PHYSICAL REV D69, 065003 (2004);

Minoru Eto, Youich Isozumi, Muneto Nitta, Keisuke Ohashi and Norisuke Sakai. J.Phys.A:Math.Gen.39 (2006) .

Date: | June 24, 2016 (Fri) 16:10~ |

Room: | S402 |

Speaker: | Satomi Okada |

Title: | Majorana Dark matter with B+L gauge symmetry |

We present a new model that extends the Standard Model (SM) with the local B + L symmetry, and point out that the lightest new fermion ζ, introduced to cancel anomalies and stabilized automatically by the B + L symmetry, can serve as the cold dark matter candidate. We study constraints on the model from Higgs measurements, electroweak precision measurements as well as the relic density and direct detections of the dark matter. Numerical results reveal that the pseudo- vector coupling of ζ with Z and the Yukawa coupling with the SM Higgs are highly constrained by the latest results of LUX, while there are viable parameter space that could satisfy all the constraints and give testable predictions.

arXiv:1604.01771（W. Chao, H. Guo, and Y. Zhang）

Date: | June 10, 2016 (Fri) 16:10~ |

Room: | S402 |

Speaker: | Takeuchi |

Title: | Path integral formalism for covariant and consistent anomalies in chiral gauge theory |

My talk is a review of the papers ( H. Banerjee, R. Banerjee and P. Mitra, Z.Physik. C 32, 445-454 (1986), K. Fujikawa and H. Suzuki, Path Integrals and Quantum Anomalies (Oxford Univ. Press, 2004) ) . It has shown that in the path integral formalism in the chiral gauge theory, the covariant anomaly are related to the consistent anomaly. They have shown the following. (1)As for the cancellation of the gauge anomaly, the covariant anomaly and the consistent anomaly are equivalent. (2)The relations of covariant anomaly to consistent anomaly are constructed directly.

H. Banerjee, R. Banerjee and P. Mitra, Z.Physik. C 32, 445-454 (1986),

K. Fujikawa and H. Suzuki, Path Integrals and Quantum Anomalies (Oxford Univ. Press, 2004)

Date: | June 3, 2016 (Fri) 16:10~ |

Room: | S402 |

Speaker: | Ryusuke Endo |

Title: | Lorentz-invariant actions for chiral p-forms
（P. Pasti, D. Sorokin and M. Tonin） |

It is knwon that naive Lorentz-covariant actions for selfdual p-form gauge fields become zero. Many attempts were made to build non-zero covariant actions. After giving a brief introduction to (selfdual) p-form gauge fields I will review the work of Pasti, Sorokin and Tonin.

A p-form is a totally antisymmetric tensor field of rank p. A p-form gauge field is a gauge field whose gauge potential is a p-form. The filed strength of the p-form gauge field is defined (in simple cases) as an exterior derivative of the p-form gauge potential, thus the field strength is a (p+1)-form. A selfdual p-form gauge field is a p-form gauge field in 2(p+1)-dimensions whose field strength is selfdual. Self dual p-form gauge fields are sometimes called chiral bosons or chiral p-forms.

Phys. Rev. D55 (1997) p.6292

Date: | May 13, 2016 (Fri) 16:10~ |

Room: | S402 |

Speaker: | Minoru Eto |

Title: | The dynamics of aloof baby Skyrmions （Petja Salmi, Paul Sutcliffe） |

The aloof baby Skyrme model is a (2+1)-dimensional theory with solitons that are lightly bound. It is a low-dimensional analogue of a similar Skyrme model in (3+1)-dimensions, where the lightly bound solitons have binding energies comparable to nuclei. A previous study of static solitons in the aloof baby Skyrme model revealed that multi-soliton bound states have a cluster structure, with constituents that preserve their individual identities due to the short-range repulsion and long-range attraction between solitons. Furthermore, there are many different local energy minima that are all well-described by a simple binary species particle model. In this paper we present the first results on soliton dynamics in the aloof baby Skyrme model. Numerical field theory simulations reveal that the lightly bound cluster structure results in a variety of exotic soliton scattering events that are novel in comparison to standard Skyrmion scattering. A dynamical version of the binary species point particle model is shown to provide a good qualitative description of the dynamics.

http://arxiv.org/abs/1511.03482

Date: | Apr. 22, 2016 (Fri) 16:10~ |

Room: | S402 |

Speaker: | Filip Blaschke |

Title: | Q-balls, Integrability and Duality |

In this talk I will review slightly older paper by Bowcock, Foster and Sutcliffe from 2009 (arxiv:0809.3895 [hep-th]). I will focus on dynamics of Q-balls, with emphasis on integrable model and also duality between Q-balls and kinks in theories with conformally flat target spaces.

Keynote

Date: | Apr. 15, 2016 (Fri) 16:10~ |

Room: | S402 |

Speaker: | Masato Arai |

Title: | Lorentzian fuzzy spheres |

It is shown that fuzzy spheres are solutions of Lorentzian IKKT matrix models. The fuzzy sphere solutions serve as toy models of closed noncommutative cosmologies where big bang/crunch singularities appear only after taking the commutative limit. The commutative limit of these solutions corresponds to a sphere embedded in Minkowski space. Perturbations are made about the solutions, and are shown to yield a scalar field theory on the sphere in the commutative limit. The scalar field can become tachyonic for a range of the parameters of the theory.

Physical Review D92 (2015) 064021

arXiv:1506.03505

Date: | Apr. 8, 2016 (Fri) 13:30~ |

Room: | 309 |

Speaker: | Asanuma/Sakurai |

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

Monopoles in the Higgs phase

(Phys.Rev. D69 (2004) 065003)

Static Properties of Nucleons in the Skyrme Model (Nucl.Phys. B228 (1983) 552)

PDF(Sakurai) PDF(Asanuma)

Date: | Apr. 1, 2016 (Fri) |

Room: | S402 |

Speaker: | Satomi Okada (D2) |

Title: | Dark matter complementarity and the Z' portal
(A. Alves, A. Berlin, S. Profumo, and F. Queiroz) |

arXiv: 1501.03490

Phys.Rev.D92.083004