Remarks on Two-Dimensional Power Correction in Soft Wall Model

Abstract

We present a direct derivation of the two-point correlation function of the vector current in the soft wall model by using the AdS/CFT dictionary. The resulting correlator is exactly the same as the one previously obtained from dispersion relation with the same spectral function as in this model. The coefficient C2 of the two-dimensional power correction is found to be C2 = —c/2 with c the slope of the Regge trajectory, rather than C2 = —c/3 derived from the strategy of the first quantized string theory. Taking the slope of the ρ trajectory c ≊ 0.9 GeV2 as input, we then obtain C2 ≊ -0.45 GeV2. The gluon condensate is found to be ⟨αsG2⟩ ≊ 0.064 GeV4, which is almost identical to the QCD sum rule estimation. By comparing these two equivalent derivation of the correlator of scalar glueball operator, we demonstrate that the two-dimensional correction cannot be eliminated by including the non-leading solution in the bulk-to-boundary propagator, as carried out by Colangelo et al.[arXiv:0711.4747]. In other words, the two-dimensional correction does exist in the scalar glueball case. Also it is manifest by using the dispersion relation that the minus sign of gluon condensate and violation of the low energy theorem are related to the subtraction scheme.