Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new user$NOmega$ dibaryon from lattice QCD near the physical point
160
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
The nucleon($N$)-Omega($Omega$) system in the S-wave and spin-2 channel ($^5$S$_2$) is studied from the (2+1)-flavor lattice QCD with nearly physical quark masses ($m_pi simeq 146$~MeV and $m_K simeq 525$~MeV). The time-dependent HAL QCD method is employed to convert the lattice QCD data of the two-baryon correlation function to the baryon-baryon potential and eventually to the scattering observables. The $NOmega$($^5$S$_2$) potential, obtained under the assumption that its couplings to the D-wave octet-baryon pairs are small, is found to be attractive in all distances and to produce a quasi-bound state near unitarity: In this channel, the scattering length, the effective range and the binding energy from QCD alone read $a_0= 5.30(0.44)(^{+0.16}_{-0.01})$~fm, $r_{rm eff} = 1.26(0.01)(^{+0.02}_{-0.01})$~fm, $B = 1.54(0.30)(^{+0.04}_{-0.10})$~MeV, respectively. Including the extra Coulomb attraction, the binding energy of $pOmega^-$($^5$S$_2$) becomes $B_{pOmega^-} = 2.46(0.34)(^{+0.04}_{-0.11})$~MeV. Such a spin-2 $pOmega^-$ state could be searched through two-particle correlations in $p$-$p$, $p$-nucleus and nucleus-nucleus collisions.
rate research
Read More
A pair of triply charmed baryons, $Omega_{ccc}Omega_{ccc}$, is studied as an ideal dibaryon system by (2+1)-flavor lattice QCD with nearly physical light-quark masses and the relativistic heavy quark action with the physical charm quark mass. The spatial baryon-baryon correlation is related to their scattering parameters on the basis of the HAL QCD method. The $Omega_{ccc}Omega_{ccc}$ in the ${^1S_0}$ channel taking into account the Coulomb repulsion with the charge form factor of $Omega_{ccc}$ leads to the scattering length $a^{rm C}_0simeq -19~text{fm}$ and the effective range $r^{rm C}_{mathrm{eff}}simeq 0.45~text{fm}$. The ratio $r^{rm C}_{mathrm{eff}}/a^{rm C}_0 simeq -0.024$, whose magnitude is considerably smaller than that of the dineutron ($-0.149$), indicates that $Omega_{ccc}Omega_{ccc}$ is located in the unitary regime.
The $OmegaOmega$ system in the $^1S_0$ channel (the most strange dibaryon) is studied on the basis of the (2+1)-flavor lattice QCD simulations with a large volume (8.1 fm)$^3$ and nearly physical pion mass $m_{pi}simeq 146$ MeV at a lattice spacing $asimeq 0.0846$ fm. We show that lattice QCD data analysis by the HAL QCD method leads to the scattering length $a_0 = 4.6 (6)(^{+1.2}_{-0.5}) {rm fm}$, the effective range $r_{rm eff} = 1.27 (3)(^{+0.06}_{-0.03}) {rm fm}$ and the binding energy $B_{Omega Omega} = 1.6 (6) (^{+0.7}_{-0.6}) {rm MeV}$. These results indicate that the $OmegaOmega$ system has an overall attraction and is located near the unitary regime. Such a system can be best searched experimentally by the pair-momentum correlation in relativistic heavy-ion collisions.
The $DeltaDelta$ dibaryon resonance $d^ast (2380)$ with $(J^P, I)=(3^+, 0)$ is studied theoretically on the basis of the 3-flavor lattice QCD simulation with heavy pion masses ($m_pi =679, 841$ and $1018$ MeV). By using the HAL QCD method, the central $Delta$-$Delta$ potential in the ${}^7S_3$ channel is obtained from the lattice data with the lattice spacing $asimeq 0.121$ fm and the lattice size $Lsimeq 3.87$ fm. The resultant potential shows a strong short-range attraction, so that a quasi-bound state corresponding to $d^ast (2380)$ is formed with the binding energy $25$-$40$ MeV below the $DeltaDelta$ threshold for the heavy pion masses. The tensor part of the transition potential from $DeltaDelta$ to $NN$ is also extracted to investigate the coupling strength between the $S$-wave $DeltaDelta$ system with $J^P=3^+$ and the $D$-wave $NN$ system. Although the transition potential is strong at short distances, the decay width of $d^ast (2380)$ to $NN$ in the $D$-wave is kinematically suppressed, which justifies our single-channel analysis at the range of the pion mass explored in this study.
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.
We calculate the low-lying spectrum of charmed baryons in lattice QCD on the $32^3times64$, $N_f=2+1$ PACS-CS gauge configurations at the almost physical pion mass of $sim 156$ MeV/c$^2$. By employing a set of interpolating operators with different Dirac structures and quark-field smearings for the variational analysis, we extract the ground and first few excited states of the spin-$1/2$ and spin-$3/2$, singly-, doubly-, and triply-charmed baryons. Additionally, we study the $Xi_c$-$Xi_c^prime$ mixing and the operator dependence of the excited states in a variational approach. We identify several states that lie close to the experimentally observed excited states of the $Sigma_c$, $Xi_c$ and $Omega_c$ baryons, including some of the $Xi_c$ states recently reported by LHCb. Our results for the doubly- and triply-charmed baryons are suggestive for future experiments.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
