Helium nuclei, deuteron, and dineutron in2+1flavor lattice QCD

Abstract

We calculate the binding energies for multi-nucleon bound states with the nuclear mass number less than or equal to 4 in 2+1 flavor QCD at the lattice spacing of a = 0.09 fm employing a relatively heavy quark mass corresponding to m π = 0.51 GeV. To distinguish a bound state from attractive scattering states, we investigate the volume dependence of the energy shift between the ground state and the state of free nucleons by changing the spatial extent of the lattice from 2.9 fm to 5.8 fm. We conclude that 4 He, 3 He, deuteron and dineutron are bound at m π = 0.51 GeV. We compare their binding energies with those in our quenched studies and also with several previous investigations.

Finite-volume electromagnetic corrections to the masses of mesons, baryons, and nuclei

“…A small number of LQCD collaborations have been calculating the binding of light nuclei and hypernuclei at unphysical light-quark masses in the isospin limit and without QED [54][55][56][57][58][59][60][61][62][63]. However, it is known that as the atomic number of a nucleus increases, the Coulomb energy increases with the square of its charge, and significantly reduces the binding of large nuclei.…”

Two-particle elastic scattering in a finite volume including QED

“…In nature, there are no bound doubly-charged two hadron systems, however such systems do exist at unphysical pion masses, as determined with Lattice QCD calculations [17,19,21,60].…”

“…QED plays a critical role in the stability and structure of nuclei, and therefore first principles calculations of nuclear structure require the inclusion of the electromagnetic (EM) interactions among quarks. Due to computational resource limitations, LQCD calculations of nuclei remain at an early stage, with calculations of the binding energies of systems with up to five nucleons and hyperons currently being performed at unphysical light-quark masses [12][13][14][15][16][17][18][19][20][21]. While the time is not yet ripe for the inclusion of QED in nuclear calculations, there are two-body scattering processes that can now be calculated with high accuracy in LQCD and where Coulomb corrections are relevant, for instance π + π + .…”

A Method for Unambiguous Detection of a Hypothetical Bound Two-Neutron System

“…Therein the emission of two correlated neutrons with low relative momentum from the excited 10 Be nucleus was observed and satisfactorily described in an effective three-body model: 8 Be gs + n + n. The only differences with respect to Ref. [1] are the way of production (n+ 9 Be → n +n+ 8 Be gs ) and somewhat higher excitation energy (E ex = 16 MeV).…”

“…Increasing the binding of the (standard) nn potential partly improves the situation but the results are inconclusive yet [4]. (iv) An interesting hint for the stronger than commonly accepted nn binding comes from lattice QCD calculations [8]. Unfortunately, these calculations were performed with a yet unrealistic pion mass of 0.51 GeV.…”