Holographic technidilaton

Technidilaton, a pseudo-Nambu-Goldstone boson of scale symmetry, was predicted long ago in the scale-invariant/walking/conformal technicolor (SWC-TC) as a remnant of the (approximate) scale symmetry associated with the conformal fixed point, based on the conformal gauge dynamics of ladder Schwinger-Dyson (SD) equation with nonrunning coupling. We study the technidilaton as a flavor-singlet bound state of technifermions by including the technigluon condensate (tGC) effect into the previous (bottom-up) holographic approach to the SWC-TC, a deformation of the holographic QCD with gamma(m) similar or equal to 0 by large anomalous dimension gamma(m) similar or equal to 1. With including a bulk scalar field corresponding to the gluon condensate, we first improve the operator product expansion of the current correlators so as to reproduce gluonic 1/Q(4) term both in QCD and SWC-TC. We find in QCD about 10% (negative) contribution of gluon condensate to the rho meson mass. We also calculate the oblique electroweak S-parameter in the presence of the effect of the tGC and find that for the fixed value of S the tGC effects dramatically reduce the flavor-singlet scalar (technidilaton) mass M-TD (in the unit of F-pi), while the vector and axial-vector masses M-rho and M-a1 are rather insensitive to the tGC, where F-pi is the decay constant of the technipion. If we use the range of values of tGC implied by the ladder SD analysis of the nonperturbative scale anomaly in the large N-f QCD near the conformal window, the phenomenological constraint S similar or equal to 0.1 predicts the technidilaton mass M-TD similar to 600 GeV which is within reach of LHC discovery.