Spectral functions of confined particles

Daniele Binosi, Ralf-Arno Tripolt
2019 Physics Letters B  
We determine the gluon and ghost spectral functions along with the analytic structure of the associated propagators from numerical data describing gauge correlators at space-like momenta obtained by either solving the Dyson-Schwinger equations or through lattice simulations. Our novel reconstruction technique shows the expected branch cut for the gluon and the ghost propagator, which, in the gluon case, is supplemented with a pair of complex conjugate poles. Possible implications of the
more » ... ions of the existence of these poles are briefly addressed. (D. Binosi). Euclidean momentum region q 2 ≥ 0 is considered, both methods agree: in the case of the (transverse) gluon propagator μν (q) = (g μν − q μ q ν /q 2 ) (q) they describe a scalar cofactor (q) that saturates in the deep infrared (IR) to a constant non-vanishing value, (0) = 1/m 2 gl > 0, which can be interpreted as being due to the dynamical generation of an effective gluon mass [9,30-32]. For the ghost particle (which appears as a consequence of the gauge fixing procedure) it is rather the dressing function F (q) = q 2 D(q), with
doi:10.1016/j.physletb.2019.135171 fatcat:s2ix5cvs2vd4pkxaxph6cbrjby