Light scalar mesons in the soft-wall model of AdS/QCD

Understand

We study light scalar mesons in the AdS/QCD soft-wall model with a background dilaton field.

• The masses and decay constants are compatible with experiment and QCD determinations if $a_0(980)$ and $f_0(980)$ are identified as the lightest scalar mesons; moreover, the states are organized in linear Regge trajectories with the same slope of vector mesons.
• Comparing the two-point correlation function of scalar operators in AdS and QCD, information about the condensates can be derived.
• Strong couplings of scalar states to pairs of light pseudoscalar mesons turn out to be small, at odds with experiment and QCD estimates: this discrepancy is related to the description of chiral symmetry breaking in this model.