TY  - JOUR
AU  - Hansen, M. T.
AU  - Romero-Lopez, F.
AU  - Sharpe, S. R.
PY  - 2021
DA  - 2021//
TI  - Decay amplitudes to three hadrons from finite-volume matrix elements
T2  - J. High Energy Phys.
JO  - Journal of High Energy Physics
SP  - 113
EP  - 44pp
VL  - 04
IS  - 4
PB  - Springer
KW  - Lattice QCD
KW  - Kaon Physics
AB  - We derive relations between finite-volume matrix elements and infinite-volume decay amplitudes, for processes with three spinless, degenerate and either identical or non-identical particles in the final state. This generalizes the Lellouch-Luscher relation for two-particle decays and provides a strategy for extracting three-hadron decay amplitudes using lattice QCD. Unlike for two particles, even in the simplest approximation, one must solve integral equations to obtain the physical decay amplitude, a consequence of the nontrivial finite-state interactions. We first derive the result in a simplified theory with three identical particles, and then present the generalizations needed to study phenomenologically relevant three-pion decays. The specific processes we discuss are the CP-violating K -> 3 pi weak decay, the isospin-breaking eta -> 3 pi QCD transition, and the electromagnetic gamma (*) -> 3 pi amplitudes that enter the calculation of the hadronic vacuum polarization contribution to muonic g – 2.
SN  - 1029-8479
UR  - https://arxiv.org/abs/2101.10246
UR  - https://doi.org/10.1007/JHEP04(2021)113
DO  - 10.1007/JHEP04(2021)113
LA  - English
N1  - WOS:000640574400001
ID  - Hansen_etal2021
ER  -