ON THE MASS-SPECTRUM OF THE SU(2) HIGGS-MODEL IN 2-DIMENSIONS(1)

We calculate the masses of the low-lying states with quantum numbers J (PC) = 0(++),1(--) in the Higgs and confinement regions of the three-d imensional SU(2) Higgs model, which plays an important role in the des cription of the thermodynamic properties of the standard model at fini te temperatures. We extract the masses from correlation functions of g auge-invariant operators which are calculated by means of a lattice Mo nte Carlo simulation, The projection properties of our lattice operato rs onto the lowest states are greatly improved by the use of smearing techniques, We also consider cross correlations between various operat ors with the same quantum numbers. From these the mass eigenstates are determined by means of a variational calculation. In the symmetric ph ase, we find that some of the ground-state masses are about 30% lighte r than those reported from previous simulations, We also obtain the ma sses of the first few excited states in the symmetric phase, Remarkabl e among these is the occurrence of a 0(++) state composed almost entir ely of gauge degrees of freedom, The mass of this state, as well as th at of its first excitations, is nearly identical to the corresponding glueball states in three-dimensional SU(2) pure gauge theory, indicati ng an approximate decoupling of the pure gauge sector from the Higgs s ector of the model. We perform a detailed study of finite-size effects and extrapolate the lattice mass spectrum to the continuum.