Present Constraints on the H-Dibaryon at the Physical Point From Lattice QCD

Abstract

The current constraints from lattice QCD on the existence of the H-dibaryon are discussed. With only two significant lattice QCD calculations of the H-dibaryon binding energy at approximately the same lattice spacing, the forms of the chiral and continuum extrapolations to the physical point are not determined. In this brief report, we consider the constraints on the H-dibaryon imposed by two simple chiral extrapolations. In both instances, the extrapolation to the physical pion mass allows for a bound H-dibaryon or a near-threshold scattering state. Further lattice QCD calculations are required to clarify this situation.

Two-Baryon Systems with Twisted Boundary Conditions

“…(6) and (7). 4 In particular, it is notable that the leading volume effects of the form e −mπL /L, e − √ 2mπL /L and e − √ 3mπL /L, can be reduced by a factor of three with i-PBCs, by setting the pion twist angle to φ π + = (…”

“…After fully quantifying both the statistical and systematic uncertainties that are inherent in LQCD calculations, the masses of the lowest-lying hadrons are found to be in impressive agreement with those of nature [1,2]. Recently, the ground-state energies of the s-shell nuclei and hypernuclei have been determined at a small number of light-quark masses [3][4][5][6][7][8][9][10]. Through algorithmic improvements, along with the growth in available computational resources, such calculations are moving towards the physical values of quark masses, and to calculations of nuclear properties such as magnetic moments.…”

Strangeness in Quark Matter: Opening Talk

“…Exotic forms of deeply bound objects with strangeness [30] and later the H di-baryon [31] was proposed by theory. Recent lattice QCD calculations suggest that the H-dibaryon is either a weakly bound system or a resonant state [32,33,16,17], and there could be strange di-baryon systems including Ξ's that can be bound [34]. An experimental confirmation of such a state would therefore be an enormous advance in the understanding of the hyperon interaction.…”

“…The enhancement of strange particle production is discussed [5,6,7,8,9] as a possible signal for the creation of a deconfined phase. Recently several observables, regarding strange and charm quarks have shown the importance of understanding the dynamics of strangeness and charm production in heavy ion collisions:• Strange particle ratios and yields from the ALICE collaboration may indicate that there is either no unique chemical freeze out point for strange an non-strange particles [10,11,12,13], or the light quark phase space is severely over-saturated [14].• Lattice calculations on the stability of the H-dibaryon indicate it might be either very loosely bound or a resonant state [15,16,17].• Viscous hydrodynamics, with fluctuating initial conditions [18] and finite but small viscous corrections, seems to describe strange hadron observables even at large baryon densities [19,20].• The hydrodynamic model calculations show sensitivity on the life time of the system and the applied equation of state [21].• There are indications that systems created in high energy p+p and p+Pb collisions can thermalize/equilibrate to a certain degree and show signs of collectivity [22,23,24,25].• A polarization of Λ's due to the finite angular momentum of the fireball is expected [26]. …”

“…• Lattice calculations on the stability of the H-dibaryon indicate it might be either very loosely bound or a resonant state [15,16,17].…”