15 research outputs found
Finite temperature properties of the Dirac operator with bag boundary conditions
We study the finite temperature free energy and fermion number for Dirac
fields in a one-dimensional spatial segment, under local boundary conditions
compatible with the presence of a spectral asymmetry. We discuss in detail the
contribution of this part of the spectrum to the determinant. We evaluate the
finite temperature properties of the theory for arbitrary values of the
chemical potential.Comment: Talk given at the Seventh International Workshop Quantum Field Theory
under the influence of External Conditions, QFEXT'05, Barcelona, Spain. Final
version, to appear in Journal of Physics A: Mathematical and Genera
Spectral action for torsion with and without boundaries
We derive a commutative spectral triple and study the spectral action for a
rather general geometric setting which includes the (skew-symmetric) torsion
and the chiral bag conditions on the boundary. The spectral action splits into
bulk and boundary parts. In the bulk, we clarify certain issues of the previous
calculations, show that many terms in fact cancel out, and demonstrate that
this cancellation is a result of the chiral symmetry of spectral action. On the
boundary, we calculate several leading terms in the expansion of spectral
action in four dimensions for vanishing chiral parameter of the
boundary conditions, and show that is a critical point of the action
in any dimension and at all orders of the expansion.Comment: 16 pages, references adde