Nonlinear Regge Trajectories With Ads/Qcd

In this work, we consider a nonquadratic dilaton φ(z)=(κz)2-α in the context of the static soft wall model to describe the mass spectrum of a wide range of vector mesons from the light up to the heavy sectors. The effect of this nonquadratic approach is translated into nonlinear Regge trajectories with the generic form M2=a(n+b)ν. We apply this sort of fits for the isovector states of ω, φ, J/ψ, and mesons and compare with the corresponding holographic duals. We also extend these ideas to the heavy-light sector by using the isovector set of parameters to extrapolate the proper values of κ and α through the average constituent mass m¯ for each mesonic specie considered. In the same direction, we address the description of possible non-qq¯ candidates using m¯ as a holographic threshold, associated with the structure of the exotic state, to define the values of κ and α. We study the π1 mesons in the light sector and the Zc, Y, and Zb mesons in the heavy sector as possible exotic vector states. Finally, the RMS error for describing these twenty-seven states with fifteen parameters (four values for κ and α respectively and seven values for m¯) is 12.61%.