On the spectra of scalar mesons from HQCD models

Understand

We determine the holographic spectra of scalar mesons from the fluctuations of the embedding of flavor D-brane probes in HQCD models.

• The models we consider include a generalization of the Sakai Sugimoto model at zero temperature and at the "high-temperature intermediate phase", where the system is in a deconfining phase while admitting chiral symmetry breaking and a non-critical 6d model at zero temperature.
• All these models are based on backgrounds associated with near extremal N_c D4 branes and a set of N_f<<N_c flavor probe branes that admit geometrical chiral symmetry breaking.
• We point out that the spectra of these models include a 0^{--} branch which does not show up in nature.