The resonant π+γ → π+π⁰ amplitude from Quantum Chromodynamics
Briceño, Raúl A
Dudek, Jozef J
Edwards, Robert G
Schultz, Christian J
Physical Review Letters
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Briceño, R. A., Dudek, J. J., Edwards, R. G., Schultz, C. J., Thomas, C., & Wilson, D. (2015). The resonant π+γ → π+π⁰ amplitude from Quantum Chromodynamics. Physical Review Letters, 115 (242001)https://doi.org/10.1103/PhysRevLett.115.242001
We present the first ab initio calculation of a radiative transition of a hadronic resonance within Quantum Chromodynamics (QCD). We compute the amplitude for ππ → πγ* , as a function of the energy of the ππ pair and the virtuality of the photon, in the kinematic regime where ππ couples strongly to the unstable ρ resonance. This exploratory calculation is performed using a lattice discretization of QCD with quark masses corresponding to m_π ≈ 400 MeV. We obtain a description of the energy dependence of the transition amplitude, constrained at 48 kinematic points, that we can analytically continue to the ρ pole and identify from its residue the ρ → πγ* form-factor.
Support is provided by the U.S. Department of Energy contract DEAC05-06OR23177 under which Jefferson Science Associates manages Jefferson Lab, the Early Career award contract DE- SC0006765, and the JSA Graduate Fellowship program. Support is also provided by the U.K. Science and Technology Facilities Council [grant number ST/L000385/1].
External DOI: https://doi.org/10.1103/PhysRevLett.115.242001
This record's URL: https://www.repository.cam.ac.uk/handle/1810/252487