Skyrmion

This is a monograph on geometrical and topological features which arise in quantum field theory. It is well known that when a chiral fermion interacts with a gauge field we have chiral anomaly which corresponds to the fact that divergence of the axial vector current does not vanish. It is observed that this is related to certain topological features associated with the fermion and leads to the realization of the topological origin of fermion number as well as the Berry phase. The role of gauge fields in the quantization procedure has its implications in these topological features of a fermion and helps us to consider a massive fermion as a soliton (skyrrnion). In this formalism chiral anomaly is found to be responsible for mass generation. This has its relevance in electroweak theory where it is observed that weak interaction gauge bosons attain mass topologically.

This thesis presents significant advances in the imaging and theory of the ultrafast dynamics of surface plasmon polariton fields. The author details construction of a sub-10 femtosecond and sub-10 nanometer spatiotemporal resolution ultrafast photoemission microscope which is subsequently used for the discovery of topological meron and skyrmion-like plasmonic quasiparticles. In particular, this enabled the creation of movies of the surface plasmon polariton fields evolving on sub-optical wavelength scales at around 0.1 femtosecond per image frame undergoing vortex phase evolution.

This brief reviews current research on magnetic skyrmions, with emphasis on formation mechanisms, observation techniques, and materials design strategies. The response of skyrmions, both static and dynamical, to various electromagnetic fields is also covered in detail.

This book focuses on the study of the dynamical properties of hadron resonances, especially their transition processes by electromagnetic and strong interactions, by using the holographic quantum chromodynamics (QCD) model. Understanding the nature of hadrons leads to revealing non-perturbative phenomena that are prominent in the low-energy region of QCD. However, there remain many open questions regarding the nature of resonant states.

This book focuses on the study of the dynamical properties of hadron resonances, especially their transition processes by electromagnetic and strong interactions, by using the holographic quantum chromodynamics (QCD) model. Understanding the nature of hadrons leads to revealing non-perturbative phenomena that are prominent in the low-energy region of QCD. However, there remain many open questions regarding the nature of resonant states.