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SUMMARY:Axial anomalies in Weyl semimetals - Prof. Jens Bardarson\, KTH Ro
 yal Technical Institute in Stockholm\, Sweden
DTSTART:20191024T131500Z
DTEND:20191024T141500Z
UID:TALK129097@talks.cam.ac.uk
CONTACT:Katarzyna Macieszczak
DESCRIPTION:I will discuss the physics of axial anomalies in Weyl semimeta
 ls. Quantum anomalies are the breaking of classical symmetries by quantum 
 fluctuations. In the case of Weyl fermions\, the relevant classical symmet
 ry is the axial symmetry\, which relates left and right handed Weyl fermio
 ns. In the presence of nonorthogonal electric and magnetic fields\, left a
 nd right handed Weyl fermions are not separately conserved\, the axial sym
 metry is broken. The physics of this was explained by Nielsen and Ninomiya
  in the eighties. The axial symmetry can also be broken in the presence of
  axial electromagnetic fields\, fields that point in the opposite directio
 n for differently handed Weyl fermions. An explanation of this phenomena i
 n the spirit of Nielsen and Ninomiya can be given\, but now requires the c
 onnection to Fermi arcs. I will explain this connection. Finally\, I will 
 briefly mention axial-torsional anomalies in Weyl semimetals. 
LOCATION:TCM Seminar Room\, Cavendish Laboratory
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