Abstract
In this work we develop a Lorentz-covariant version of the previously derived formalism for relating finite-volume matrix elements to 2+J→2 transition amplitudes. We also give various details relevant for the implementation of this formalism in a realistic numerical lattice QCD calculation. Particular focus is given to the role of single-particle form factors in disentangling finite-volume effects from the triangle diagram that arise when J couples to one of the two hadrons. This also leads to a new finite-volume function, denoted G, the numerical evaluation of which is described in detail. As an example we discuss the determination of the ππ+J→ππ amplitude in the ρ channel, for which the single-pion form factor, Fπ(Q2), as well as the scattering phase, δππ, are required to remove all power-law finite-volume effects. The formalism presented here holds for local currents with arbitrary Lorentz structure, and we give specific examples of insertions with up to two Lorentz indices.
Original language | English |
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Article number | 034511 |
Journal | Physical Review D |
Volume | 100 |
Issue number | 3 |
DOIs | |
State | Published - Aug 13 2019 |
Externally published | Yes |
Funding
R. A. B. acknowledges support from U.S. Department of Energy Contract No. DE-AC05-06OR23177, under which Jefferson Science Associates, LLC, manages and operates Jefferson Lab, and the U.S. Department of Energy Early Career award Contract No. DE-SC0019229. A. B. acknowledges support from U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Award No. DE-SC0010300. The authors would like to thank A. Jackura, as well as J. Dudek, R. Edwards, D. Wilson, and the rest of the Hadron Spectrum Collaboration for useful discussions.
Funders | Funder number |
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U.S. Department of Energy | DE-SC0019229, DE-AC05-06OR23177 |
Nuclear Physics | DE-SC0010300 |
Office of Science |