I.F.T.

Seminario

(Seminar)

November 21st 2000 Tuesday, 15:00 p.m.

The Nucleon and the Neutron Star

Vikram Soni

(National Physical Laboratory, New Delhi)

At typical central densities of neutron stars (5 - 10 times nuclear density) the nucleon is resolved and therefore composite. It is then unwise to use purely nucleonic or hadronic degres of freedom as has been custom. On the other hand, perturbative QCD applies at much higher density. We use a renormalizable effective Lagrangian , that is QCD coupled to a chiral multiplet ($\pi$ , $\sigma$) which can interpolate between all desities. It yields the nucleon as a quark soliton and also admits several interesting phases at high density. The ground state for the core of a neutron star is found to be a pion condensate (for 2 flavour matter). This ground state is anisotropic and lines up the magnetic moments of the constituent quarks to dynamically yield strong magnetic fields of typical strength of those found in pulsars.

Where: Modulo C-XVI, 3rd floor, Facultad de Ciencias U.A.M., C.U. Cantoblanco, 28049-Madrid