Light Meson Form Factors at near Physical Masses

Abstract

The ability for most hadrons to decay via strong interactions prevents the direct measurement of their electromagnetic properties. However, a detailed understanding of how these resonant states feature in scattering processes can allow one to disentangle such information from photo production processes. In particular, there has been increasing interest in the determination of magnetic dipole moments using such methods. In a recent study, Gudino et al. provide the first experimental determination of the magnetic dipole moment of the rho meson. To facilitate a comparison with this experimental determination, we present a calculation of the rho meson and pion electromagnetic form factors calculated in the framework of Lattice QCD. Using the PACS-CS 2+1 flavour full QCD gauge field configurations, we are able to access low $Q^2$ values at near-physical quark masses. Through the use of variational techniques, we control excited state systematics in the matrix elements of the lowest-lying states and gain access to the matrix elements of the first excited state. Our determination of the rho meson $g$-factor $g_{\rho }=2.21(8)$ is in excellent agreement with this experimental determination, but with a significantly smaller uncertainty.

16 pages, 13 figures

References in corpus (6)

• Toward the excited meson spectrum of dynamical QCD
• pi- and rho-mesons, and their diquark partners, from a contact interaction
• Vector meson form factors and their quark-mass dependence
• Pseudoscalar and vector meson form factors from lattice QCD
• Magnetic moments of vector, axial, and tensor mesons in lattice QCD
• Derivative sources in lattice spectroscopy of excited light-quark mesons

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• Constraining beyond the Standard Model nucleon isovector charges
• Hadronic structure on the light-front VIII. Light scalar and vector mesons
• Unpolarized generalized parton distributions of light and heavy vector mesons
• $\Delta I=3/2$ and $\Delta I=1/2$ channels of $K\to \pi \pi$ decay at the physical point with periodic boundary conditions
• Valence quark distribution of light $\rho$ and heavy $J/\psi$ vector mesons in light-cone quark model
• Medium effects on the electromagnetic form factors of the $\rho$ meson
• Radiative Decays of Vector Mesons with Light-Cone Sum Rules