ππ →πγ∗ amplitude and the resonant ρ →πγ∗ transition from lattice QCD
| Autor: | Briceño, RA, Dudek, JJ, Edwards, RG, Shultz, CJ, Thomas, CE, Wilson, DJ |
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| Přispěvatelé: | Thomas, Christopher [0000-0001-8817-4977], Wilson, David [0000-0003-2364-1161], Apollo - University of Cambridge Repository |
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
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| Popis: | We present a determination of the $P$-wave $\pi\pi\to\pi\gamma^\star$ transition amplitude from lattice quantum chromodynamics. Matrix elements of the vector current in a finite-volume are extracted from three-point correlation functions, and from these we determine the infinite-volume amplitude using a generalization of the Lellouch-L\"uscher formalism. We determine the amplitude for a range of discrete values of the $\pi\pi$ energy and virtuality of the photon, and observe the expected dynamical enhancement due to the $\rho$ resonance. Describing the energy dependence of the amplitude, we are able to analytically continue into the complex energy plane and from the residue at the $\rho$ pole extract the $\rho\to \pi \gamma^\star$ transition form factor. This calculation, at $m_\pi\approx 400$ MeV, is the first to determine the form factor of an unstable hadron within a first principles approach to QCD. Science and Technology Facilities Council (Grant ID: ST/L000385/1) This is the author accepted manuscript. The final version is available from the American Physical Society via http://dx.doi.org/10.1103/PhysRevD.93.114508 |
| Databáze: | OpenAIRE |
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