Hosted by: Semeon Valgushev

Abstract: It has been over three decades since the first two-baryon studies from lattice QCD were performed. Despite algorithmic improvements and increases in computational resources since then, there remains disagreement on results from various groups in the lattice community. A major barrier in resolving these discrepancies is the poor signal-to-noise ratio for baryons, which needs to be overcome with modern methods. In this seminar, I will begin by covering various techniques and formalism that have become standard in lattice spectroscopy. This will include the use of distillation (and its stochastic variant) to treat all-to-all quark propagation; a variational method, which can help to reduce unwanted excited states while allowing for several desired states to be extracted; and the L\"uscher two-particle formalism, which relates finite-volume energies to infinite-volume scattering amplitudes. I will then present our recent results for two nucleon S-wave interactions in both isospin channels, computed at the SU(3)-flavor-symmetric point corresponding to mπ≈714 MeV. These results strongly disfavor the presence of any bound states at this pion mass, which contradicts some of the calculations in the literature. Further, our recent results for the H dibaryon—-also using an SU(3)-symmetric setup, but corresponding to mπ≈420 MeV—-show appreciable dependence on the lattice spacing. This could explain some of the discrepancies in the literature. However, I will discuss other possibilities, as well as future directions for spectroscopy.