Strong couplings and form factors of charmed mesons in holographic QCD

We extend the two-flavor hard-wall holographic model of Erlich, Katz, Son, and Stephanov [Phys. Rev. Lett. 95, 261602 (2005)] to four flavors to incorporate strange and charm quarks. The model incorporates chiral and flavor symmetry breaking and provides a reasonable description of masses and weak decay constants of a variety of scalar, pseudoscalar, vector, and axial-vector strange and charmed mesons. In particular, we examine flavor symmetry breaking in the strong couplings of the $\rho$ meson to the charmed $D$ and $D^{*}$ mesons. We also compute electromagnetic form factors of the $\pi$, $\rho$, $K$, $K^{*}$, $D$ and $D^{*}$ mesons. We compare our results for the $D$ and $D^{*}$ mesons with lattice QCD data and other nonperturbative approaches.

Figure 1

Electromagnetic form factor of the pion (solid line) compared to experimental data [62] (points with error bars).

Figure 2

The electric (blue), magnetic (red), and quadrupole (green) EM form factors of the $\rho$ meson.

Figure 3

Electromagnetic form factor of the kaon (solid line) compared to experimental data [63] (points with error bars).

Figure 4

The electric (blue), magnetic (red) and quadrupole (green) EM form factors of the $K^{*}$ meson.

Figure 5

Electromagnetic form factor of the $D$ meson (solid line) compared to lattice QCD data [44] (points with error bars).

Figure 6

The electric (blue), magnetic (red), and quadrupole (green) EM form factors of the $D^{*}$ meson. The electric form factor $F_{D^{*}}^E(Q^2)$ (solid blue line) is compared to lattice QCD data [44] (points with error bars).

Figure 7

Large $Q^2$ behavior for the $D$-meson, kaon and pion electromagnetic form factor.

Figure 8

Large $Q^2$ behavior for the $D^{*}$-meson, $K^{*}$-meson and $\rho$-meson electromagnetic form factor.