SEMINAR BY JAVIER SUBILS (NORDITA)

Place and time: Naustið, March 2, 2023, 14.30

Speaker: Javier Subils, NORDITA

Title: A holographic view on monopoles, baryons and confinement

Abstract:
Understanding the phase diagram of QCD at finite density and temperature remains one of the most prominent open problems in modern physics. In this talk, I will present a model in type IIA supergravity that describes holographically a QCD-like theory at strong coupling. The theory possesses a global U(1) symmetry under which magnetic monopoles are charged. I will show how the phase diagram at finite temperature and external magnetic field looks like. This turns out to be quite rich, both with first and second order confinement/deconfinement phase transitions and a critical point. Finally, I will explain how these results are leading us to find the first realization of finite baryon density in a top-down confining holographic model.

NORNDiP: International Women’s day, March 8

The Nordic Network for Diversity in Physics, NORNDiP, will celebrate the International Women’s day with a virtual event which takes place on March 8.

Highlights of the event:

  • 1:00 PM GMT: Meytal Eran Jona, Career of Women in Physics.
  • 2:00 PM GMT: Jane Rigby, The James Webb Space Telescope (JWST): Launch, commissioning, and getting ready for science.

Attendance is free of charge, but registration is mandatory to get access to the Zoom link and the recorded videos.
For more details about the conference, program, and the NORNDiP network visit: https://www.norndip.net
Registration at this link: https://indico.cern.ch/event/1127031/

SEMINAR BY CRISTOBAL ARRATIA (NOV. 26TH 10:00)

Place and time: Friday November 26th at 10:00, VRII-152

Speaker: Cristobal Arratia, NORDITA

Title: A story on hydrodynamics, instabilities, and transition to turbulence

Abstract:
Fluid mechanics is an old subject. It is present in our everyday experience and its governing equations were written nearly two centuries ago, yet we have long struggled to explain very common phenomena. In this talk we will see a part of its history, starting with the experiments of Reynolds (1883). These contain examples of the two ways in which complex behaviour arises in fluids and other systems: through an unstable eigenmode of the linearized dynamics around a simple state, and in the absence of such an instability. After describing some general insights for the study of instabilities that were learnt during the last few decades, we will return to the main subject of Reynolds paper, the transition to turbulence in a pipe. We will describe how this problem has finally been understood during the last decade thanks to a model by Barkley. We will end on some current perspectives on how this model can be extended to other transitional flows with much richer dynamics.

Seminar by Habib Rostami (Nov. 5th 10:00)

Place and time: Friday November 5th at 10:00, Oddi 206

Speaker: Habib Rostami

Title: Strain physics in 2D materials: pseudo gauge field, piezoelectricity and acoustoelectric

Abstract: In the context of applied physics, we are always interested in controlling and modifying the intrinsic electronic properties of electronic systems. For instance, we can use electric and magnetic fields for this purpose. However, mechanical deformation is another external field that is not as common as electric and magnetic fields. Two-dimensional van der Walls layered materials such as graphene and transition metal dichalcogenides (TMDs) show remarkable elastic properties with strong in-plane Yang modulus and weak bending rigidity. Accordingly, they provide a promising platform for flexible electronics, optoelectronic and acousto-optic devices. I will review the manifestation of a fictitious (pseudo) gauge field in 2D materials owing to the lattice deformation. Pseudo gauge field results in an ultra-strong pseudo magnetic field preserving the time-reversal symmetry and leading to the flat-band (Landau level) formation. I will discuss strain-induced electric polarization due to the piezoelectric effect related to a topological quantity known as the valley Chern number in inversion broken TMDs. I will talk about highly efficient exciton drift mechanism in single-layer TMD owing to the strain-induced deformation potential, the built-in piezoelectric field and the pseudo magnetic field. I will present acoustogalvanic effect as a rectification process of propagating pseudo electromagnetic field (sound wave) in 2D and 3D Dirac materials. I will discuss a transverse acoustoelectric current due to a pseudo gauge field that can propagate transverse to sound propagation.