Seminars Home


HIP seminar room A315

  • Tuesday 8 August 2017 at 10.15 in E204: Jean-Paul Blaizot (Saclay). Special Colloquium, note place!
    Bose-Einstein condensation in unusual circumstances
    Abstract: There is robust evidence from the Relativistic Heavy Ion Collider (RHIC) in the USA, and now from the Large Hadron Collider (LHC) at CERN, that the matter produced in ultra-relativistic heavy ion collisions reaches (nearly) local equilibrium. According to our present understanding, the initial state of this matter consists of gluons, the quanta of the gluon field responsible for the strong interactions of elementary particles. These gluons are bosons, and are too numerous, given their energy, to be accommodated by an ordinary thermal distribution. If their number remains approximately constant as they evolve toward equilibrium, that is, if inelastic processes are sufficiently slow, a natural, albeit controversial, possibility is that the excess gluons form a Bose-Einstein condensate. Aside from its potential relevance to the problem of thermalization of the quark-gluon plasma in ultra-relativistic heavy ions, the dynamical formation of such a condensate is an interesting problem in itself, with connections to diverse fields of physics, ranging from cosmology to cold atom systems. Several aspects of this problem will be addressed in the talk.

  • Tuesday 15 August 2017 at 10.15 in A315: Martin Krššák (Tartu)
    Modified teleparallel theories
    Abstract: One of the greatest challenges of modern theoretical physics is explanation of the accelerated expansion of the Universe. The usual approach is to introduce the Dark Energy, but recently another approach started to be increasingly popular, where the laws of gravity are reconsidered and modified. It turns out that it is possible to modify general relativity not only in its standard formulation, but also in the so-called teleparallel formulation. This leads to novel modified models, e.g. f(T) gravity. I will present some recent results in this field. In the first part, I will discuss some problems of f(T) gravity and how to overcome them, and then in the second part I will show some new ways to formulate novel models of gravity.

  • Tuesday 22 August 2017 at 10.15 in A315: Vasily Tarasov (Moscow State University)
    Abstract: TBA

  • Tuesday 29 August 2017 at 10.15 in A315: Stanislav Rusak (Nordita)
    Abstract: TBA

  • Tuesday 26 September 2017 at 10.15 in A315: Oliver Gould (Imperial College, London)
    Abstract: TBA

  • Tuesday 3 October 2017 at 10.15 in A315: Hiren Patel (UMass Amherst)
    Abstract: TBA

  • Tuesday 10 October 2017 at 10.15 in A315: Tomas Brauner (Stavanger)
    Nuclear matter without nucleons and Bose-Einstein condensation in strong magnetic fields
    Abstract: Topological soliton lattices are known in condensed-matter physics, for instance in liquid crystals or chiral magnets. In this talk, I will argue that a similar structure appears also in dilute nuclear matter. Sufficiently strong magnetic fields destabilize ordinary nuclear matter and lead to the formation of a chiral soliton lattice (CSL) of neutral pions. This is a model-independent result based on low-energy effective field theory, and the magnetic fields and baryon densities required may occur in the cores of neutron stars. The spectrum of excitations above the CSL ground state contains a soft, nonrelativistic mode that gives an anomalous contribution to pressure, scaling with temperature and magnetic field as T^{5/2}B^{3/2}. Finally, I will argue that in stronger but still achievable magnetic fields, the neutral pion CSL background may catalyze Bose-Einstein condensation of charged pions.

Hopefully the up to 50 min + 10 min discussion long seminar/colloquium will be understandable to a wide audience.
Contacts: Keijo Kajantie (keijo kajantie at helsinki fi) [department / HIP seminar],
Francesco Montanari (francesco montanari at helsinki fi) [cosmo seminar]

Other related seminars

Friday 10-12 seminar series in D117: Astrophysics seminar.
Mathematical Physics Seminar and Workshop series Wed 14-16 in Exactum C123.