Upcoming events

  • Bethe-Colloquium by Carsten Urbach, November 13th 2014
  • Bethe-Colloquium by Alain Connes, November 27th 2014
  • Bethe-Colloquium by Arthur Hebecker, January 15th 2015

Further information will be given as soon as they are available.

Bethe Colloquium by Prof. Carsten Urbach

November 2014

November's Bethe Colloquium will take place on November 13th (3:15 pm) in Hörsaal I:

  • Carsten Urbach (HISKP, Bonn)
  • Axial U(1) anomaly in QCD and the Witten-Veneziano formula
  • Hörsaal I, Physikalisches Institut

Abstract: In the 70ties of the last century the mass spectrum of the light pseudoscalar mesons posed a puzzle: the eta' meson is way too heavy for being a (pseudo) Golstone boson. This was explained eventually with the anomalously broken axial U(1) symmetry together with topological effects in QCD. While this solution is mainly based on perturbative arguments, we will discuss how to determine the light pseudoscalar meson spectrum non-perturbatively using lattice QCD. Moreover, we will relate the so determined masses to the U(1) anomaly using the famous Witten-Veneziano formula.

Bethe Colloquium by Prof. Alain Connes

November 2014

A second Bethe Colloquium is scheduled for November. It will take place on November 27th (3:15 pm) in Hörsaal I:

  • Alain Connes (College de France, Paris)
  • Quanta of Geometry
  • Hörsaal I, Physikalisches Institut

Abstract: In the construction of spectral manifolds in noncommutative geometry, a higher degree Heisenberg commutation relation involving the Dirac operator and the Feynman slash of real scalar fields naturally appears and implies, by equality with the index formula, the quantization of the volume. We first show that this condition implies that the manifold decomposes into disconnected spheres which will represent quanta of geometry. We then refine the condition by involving the real structure and two types of geometric quanta, and show that connected manifolds with large quantized volume are then obtained as solutions. When this condition is adopted in the gravitational action it leads to the quantization of the four volume with the cosmological constant obtained as an integration constant. Restricting the condition to a three dimensional hypersurface implies quantization of the three volume and the possible appearance of mimetic dark matter. When restricting to a two dimensional hypersurface, under appropriate boundary conditions, this results in the quantization of area and has many interesting applications to black hole physics.