Universal scaled Higgs-mass gap for the bilayer Heisenberg model in the ordered phase

The spectral properties for the bilayer quantum Heisenberg model were investigated withthe numerical diagonalization method. In the ordered phase, there appears the massiveHiggs excitation embedded in the continuum of the Goldstone excitations. Recently, it wasclaimed that the properly scaled Higgs mass is a universal constant inproximity to the critical point. Diagonalizing the finite-size cluster withN ≤ 36spins, we calculated the dynamical scalar susceptibility(Formula Presented.),which is rather insensitive to the Goldstone mode. Afinite-size-scaling analysis of (Formula Presented.)is made, and the universal (properly scaled) Higgs massis estimated.