Speaker
Description
We study the systematic error associated with the truncation of the derivative expansion for the potential in HAL QCD method. We introduce the Hamiltonian with the leading-order potential determined in the HAL QCD method and study the corresponding eigenmodes in a finite volume. We show that a temporal correlation function of a designated energy eigenstate can be obtained using the finite-volume eigenwavefunction as a projection operator. This enables us to make quantitative comparison between Luscher's method and HAL QCD method in terms of the energy spectra in a finite volume, avoiding the notorious pseudo-plateau problem in a temporal correlation function [1].
Numerical investigations are performed for the Omega_ccc - Omega_ccc (1S0) system near the physical point [2]. We observe consistency in finite volume spectra, which indicates that the truncation error of derivative expansion is small in this system. This study also gives clear demonstration that the potential (and thus phase shifts/binding energy) can be reliably extracted from the NBS wave function for elastic excited states.
[1] T. Iritani et al. (HAL QCD Coll.), JHEP 03 (2019) 007, arXiv:1812.08539 [hep-lat].
[2] Y. Lyu, H. Tong et al., arXiv:2102.00181 [hep-lat].
