2019/05/31 by Antonio Pineda, Jaume Tarrús Castellà
Physics and Astronomy · #Hadron #High-Energy Particle Collisions Research #Lambda #Multipole expansion #Particle physics #Particle physics theoretical and experimental studies #Physics #Pion #Quantum Chromodynamics and Particle Interactions #Quantum chromodynamics #Quantum mechanics #Quarkonium #Unitarity #hep-ex #hep-ph #nucl-th
paper · pdf · doi:10.1103/physrevd.100.054021
published as Phys. Rev. D 100, 054021 (2019) · 50 pages, 7 figures. Journal version. The experimental data set used for the $Υ(2S)\to Υ(1S)ππ$ transition has been changed due to problems in the original one that made it unreliable
arxiv created 2019/09/18 · openalex publication_date 2019/09/18 · arxiv updated 2019/09/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We compute hadronic transitions between heavy quarkonium states with two, or one, pion/eta particles in the final state. We use the multipole expansion but not the twist expansion. The latter cannot be justified for the energy release of hadronic transitions between heavy quarkonium states with different principal quantum numbers. Instead, we use a counting based on the dimension of the interpolating field of the hybrid. This alternative counting allows us to still use chiral low-energy theorems to compute the pion production by local gluonic operators. We explore the phenomenological impact of this counting. Remarkably enough, for the two-pion transitions, we obtain the same predictions for the normalized differential decay rate as those obtained assuming the twist expansion. We implement this computational scheme using the hadronic representation of the effective theory potential NRQCD. We assume that the inverse Bohr radius of the heavy quarkonium is much larger than \mathrm\ensuremathΛQCD but do not impose any constraint on the relative size of \mathrm\ensuremathΛQCD and the typical kinetic energy of the bound state.