We investigate baryon-baryon (BB) interactions in the 3-flavor full QCD simulations with degenerate quark masses for all flavors. The BB potentials i

BACKGROUND AND PURPOSE: The incidence of wall enhancement of cerebral aneurysms on vessel wall MR imaging has been described as higher in ruptured intracranial aneurysms than in unruptured intracranial aneurysms, but the difference in the degree of enhancement between ruptured and unruptured aneurysms is unknown. We compared the degree of enhancement between ruptured and unruptured intracranial aneurysms by using quantitative MR imaging measures. MATERIALS AND METHODS: We performed quantitative analyses of circumferential enhancement along the wall of cerebral aneurysms in 28 ruptured and 76 unruptured consecutive cases by using vessel wall MR imaging. A 3D-T1-weighted fast spin-echo sequence was obtained before and after contrast media injection, and the wall enhancement index was calculated. We then compared characteristics between ruptured and unruptured aneurysms. RESULTS: The wall enhancement index was significantly higher in ruptured than in unruptured aneurysms (1.70 ± 1.06 versus 0.89 ± 0.88, respectively; P = .0001). The receiver operating characteristic curve analysis found that the most reliable cutoff value of the wall enhancement index to differentiate ruptured from unruptured aneurysms was 0.53 (sensitivity, 0.96; specificity, 0.47). The wall enhancement index remained significant in the multivariate logistic regression analysis (P < .0001). CONCLUSIONS: Greater circumferential enhancement along the wall of cerebral aneurysms correlates with the ruptured state. A quantitative evaluation of circumferential enhancement by using vessel wall MR imaging could be useful in differentiating ruptured from unruptured intracranial aneurysms.

We construct energy-independent but nonlocal potentials above inelastic thresholds, in terms of Nambu-Bethe-Salpeter wave functions defined in quantum field theories such as QCD. As an explicit example, we consider $NN\to NN+n\pi$ scattering processes for $n=0,1,2,\dots$. We show the existence of energy-independent coupled channel potentials with a nonrelativistic approximation, where momenta of all particles are small compared with their own masses. In the case of two-body inelastic scatterings such as $\Lambda \Lambda \to \Lambda \Lambda$, $N\Xi$, $\Sigma \Sigma$, on the other hand, we show that energy-independent potentials can be constructed without relying on nonrelativistic approximations. We also propose a method to extract these potentials using time dependence of general correlation functions.

There exist two methods to study two-baryon systems in lattice QCD: the direct method which extracts eigenenergies from the plateaux of the temporal correlation function and the HAL QCD method which extracts observables from the non-local potential associated with the tempo-spatial correlation function. Although the two methods should give the same results theoretically, there have been reported qualitative difference for observables from lattice QCD simulations. Recently, we pointed out in [1, 2] that the separation of the ground state from the excited states is crucial to obtain sensible results in the former, while both states provide useful signals for observables in the latter. In this paper, we identify the contribution of each state in the direct method by decomposing the two-baryon correlation functions into the finite-volume eigenmodes obtained from the HAL QCD method. As in our previous studies, we consider the ΞΞ system in the ¹S₀ channel at m _π = 0.51 GeV in (2+1)-flavor lattice QCD using the wall and smeared quark sources with spatial extents, La = 3.6, 4.3, 5.8 fm. We demonstrate that the “pseudo-plateau” at early time slices (t = 1 ∼ 2 fm) from the smeared source in the direct method indeed originates from the contamination of the excited states, and the plateau with the ground state saturation is realized only at t > 5 ∼ 15 fm corresponding to the inverse of the lowest excitation energy. We also demonstrate that the two-baryon operator can be optimized by utilizing the finite-volume eigenmodes, so that (i) the finite-volume energy spectra from the HAL QCD method agree with those from the temporal correlation function with the optimized operators and (ii) the correct finite-volume spectra would be accessed in the direct method only if highly optimized operators are employed. Thus we conclude that the long-standing issue on the consistency between Lüscher’s finite volume method and the HAL QCD method for two baryons is now resolved at least for this particular system considered here: they are consistent with each other quantitatively only if the excited contamination is properly removed in the former.

We study a doubly bottomed tetraquark state $(bb\overline{u}\overline{d})$ with quantum number $I(J^P)=0(1^{+})$, denoted by $T_{bb}$, in lattice QCD with the nonrelativistic QCD (NRQCD) quark action for $b$ quarks. Employing ($2+1$)-flavor gauge configurations at $a\approx 0.09\mathrm{fm}$ on ${32}^3\times 64$ lattices, we have extracted the coupled-channel potential between $\overline{B}{\overline{B}}^{*}$ and ${\overline{B}}^{*}{\overline{B}}^{*}$ in the HAL QCD method, which predicts an existence of a bound $T_{bb}$ below the $\overline{B}{\overline{B}}^{*}$ threshold. By extrapolating results at $m_{\pi }\approx 410$, 570, 700 MeV to the physical pion mass $m_{\pi }\approx 140\mathrm{MeV}$, we obtain a binding energy with its statistical error as $E_{\text{binding}}^{(\mathrm{single})}=155(17)\mathrm{MeV}$ and $E_{\text{binding}}^{(\mathrm{coupled})}=83(10)\mathrm{MeV}$, where “coupled” means that effects due to virtual ${\overline{B}}^{*}{\overline{B}}^{*}$ states are included through the coupled channel potential, while only a potential for a single $\overline{B}{\overline{B}}^{*}$ channel is used in the analysis for “single.” A comparison shows that the effect from virtual ${\overline{B}}^{*}{\overline{B}}^{*}$ states is quite sizable to the binding energy of $T_{bb}$. We estimate systematic errors to be $\pm 20\mathrm{MeV}$ at most, which are mainly caused by the NRQCD approximation for $b$ quarks.