Speaker: Dr. Vincnezo Vitagliano from Keio University

Abstract:
External conditions have a dramatic impact on the way dynamical symmetry breaking occurs. I will review some recent (and some less recent) results of symmetry breaking in curved spacetime. Flirting with the contemporary interest toward 2D engineered material, I will then move on potential applications on geometrically deformed lattices. In a curved background, the natural expectation is that curvature works toward the restoration of an internal symmetry. I will show instead that, for topological defects, the competing action of the locally induced curvature and of boundary conditions generated by the non-trivial topology allows configurations where symmetries can be spontaneously broken close to the core.

[Topology and Geometry Seminar] "Solving Word Problems in finitely presented groups" by Robert Tang

"Ultra-strong light-matter interactions and super-radiant phase transitions" by Prof Motoaki Bamba, Osaka Univ

Speaker
Dr. Tomoaki Matsuura, Associate Professor at Department of Biotechnology, Graduate School of Engineering, Osaka University.

Topology and Geometry unit seminar

Dr. Sebastian Reinig, Postdoc, National Institute of Genetics.  Language: English

"Broadband plasmonics in the optical and THz range" by Prof. Venu Gopal Achanta, DCMP&MS, Tata Institute of Fundamental Research, Mumbai, India

Internal Seminar, Friday August 3rd, C700, 4-5pm

Internal Seminar, Friday August 3rd, 2018, 4pm

This talk will take as a starting point the Skyrmions as baryons in large-N QCD. It is further assumed that at high density, the sextic term in derivatives becomes dominant at some large density. This assumption is based on the observation that the term behaves like a perfect fluid, which is welcome for nuclear matter at large density – an environment suitable for the studies of neutron stars. With very large masses and compact radii, neutron stars become the closes known stable objects to the critical line of gravitational collapse. With some phenomenological motivation in mind, we consider the possibilities of finding exact analytic solutions to a system which is approximated by the sextic derivative term and a potential; this system is called the BPS-Skyrme model. We find a condition for when the gravitating soliton equations can be solved exactly and deduce the phenomenological implications. We furthermore find that this system has the peculiarity of not having stable black holes, meaning that the soliton cannot become scalar hair of a black hole. This is somewhat surprising, because the Skyrme soliton with a fourth-order derivative term can become stable black hole hair. We write down a class of models with higher-order derivative terms and find 2 new models that can sustain stable hair and 2 new that cannot.

Finally, we consider the problem of the classical binding energies of the Skyrmions, which are far too large compared to nuclei and explain a solution to this problem based on holography. Interestingly the solution from holography relates the baryon to the instanton of a 5-dimensional theory and the moduli of the instanton become massive modes in the Skyrmion. These modes in addition to the zero modes of the Skyrmion are expected to describe the spectra of nuclei.