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Volume 334 - The 36th Annual International Symposium on Lattice Field Theory (LATTICE2018) - Hadron Spectroscopy and Interactions
Calculating the $\rho$ radiative decay width with lattice QCD
L. Leskovec,* C. Alexandrou, J. Negele, S. Meinel, S. Paul, M. Petschlies, A. Pochinsky, G. Rendon, S. Syritsyn
*corresponding author
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Published on: 2019 May 29
We present the results of our lattice QCD study of the $\pi\gamma\to\pi\pi$ process, where the $\rho$ resonance appears as an enhancement in the transition amplitude. We use $N_f=2+1$ clover fermions on a lattice of $L=3.6$ fm and a pion mass of $320$ MeV. Using a combination of forward, stochastic, and sequential propagators, we calculate the two-point and three-point functions that allow us to determine the $\pi\gamma\to\pi\pi$ matrix elements for several values of the invariant mass $s$ and momentum transfer $q^2$. To fit the $q^2$ and $s$ dependence of the $\pi\gamma\to\pi\pi$ amplitude, we explore a set of general parametrizations based on a Taylor expansion. By analytic continuation to the complex pole corresponding to the $\rho$ resonance, we determine the resonant form factors and calculate the radiative decay width of the $\rho$.
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