100 research outputs found
potential in the HAL QCD method with all-to-all propagators
In this paper, we perform the first application of the hybrid method (exact
low modes plus stochastically estimated high modes) for all-to-all propagators
to the HAL QCD method. We calculate the HAL QCD potentials in the
scattering in order to see how statistical fluctuations of the
potential behave under the hybrid method. All of the calculations are performed
with the 2+1 flavor gauge configurations on lattice at the
lattice spacing fm and MeV. It is
revealed that statistical errors for the potential are enhanced by stochastic
noises introduced by the hybrid method, which, however, are shown to be reduced
by increasing the level of dilutions, in particular, that of space dilutions.
From systematic studies, we obtain a guiding principle for a choice of dilution
types/levels and a number of eigenvectors to reduce noise contaminations to the
potential while keeping numerical costs reasonable. We also confirm that we can
obtain the scattering phase shifts for the system by the hybrid
method within a reasonable numerical cost, which are consistent with the result
obtained with the conventional method. The knowledge we obtain in this study
will become useful to investigate hadron resonances which require quark
annihilation diagrams such as the meson by the HAL QCD potential with
the hybrid method.Comment: 20 pages, 10 figures, published version in PTE
Baryon interactions from lattice QCD with physical quark masses -- Nuclear forces and forces --
We present the latest lattice QCD results for baryon interactions obtained at
nearly physical quark masses. nonperturbatively -improved Wilson quark action with stout smearing and Iwasaki gauge
action are employed on the lattice of (96a)^4 \simeq (8.1\mbox{fm})^4 with
GeV, where MeV and MeV.
In this report, we study the two-nucleon systems and two- systems in
channel and - coupled channel, and extract central and
tensor interactions by the HAL QCD method. We also present the results for the
interaction in channel which is relevant to the
pair-momentum correlation in heavy-ion collision experiments.Comment: Talk given at 35th International Symposium on Lattice Field Theory
(Lattice 2017), Granada, Spain, 18-24 Jun 2017, 8 pages, 9 figures. arXiv
admin note: text overlap with arXiv:1702.0160
I=2ππ potential in the HAL QCD method with all-to-all propagators
In this paper, we perform the first application of the hybrid method (exact low modes plus stochastically estimated high modes) for all-to-all propagators to the HAL QCD method. We calculate the HAL QCD potentials in the I=2ππ scattering in order to see how statistical fluctuations of the potential behave under the hybrid method. All of the calculations are performed with the 2+1 flavor gauge configurations on a 163×32 lattice at the lattice spacing a≈0.12 fm and mπ≈870 MeV. It is revealed that statistical errors for the potential are enhanced by stochastic noises introduced by the hybrid method, which, however, are shown to be reduced by increasing the level of dilutions, in particular, that of space dilutions. From systematic studies, we obtain a guiding principle for a choice of dilution types/levels and a number of eigenvectors to reduce noise contamination to the potential while keeping numerical costs reasonable. We also confirm that we can obtain the scattering phase shifts for the I=2ππ system by the hybrid method within a reasonable numerical cost; these phase shifts are consistent with the result obtained with the conventional method. The knowledge that we obtain in this study will become useful for the investigation of hadron resonances that require quark annihilation diagrams such as the ρ meson by the HAL QCD potential with the hybrid method
Most Strange Dibaryon from Lattice QCD
The system in the 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) and nearly physical pion mass MeV
at a lattice spacing fm. We show that lattice QCD data
analysis by the HAL QCD method leads to the scattering length , the effective range and the binding energy . These results indicate that the
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.Comment: 6 pages and 4 figure
dibaryon from lattice QCD near the physical point
The nucleon()-Omega() system in the S-wave and spin-2 channel
(S) is studied from the (2+1)-flavor lattice QCD with nearly physical
quark masses (~MeV and ~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 (S) 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 ~fm, ~fm, ~MeV,
respectively. Including the extra Coulomb attraction, the binding energy of
(S) becomes ~MeV. Such a spin-2 state could be
searched through two-particle correlations in -, -nucleus and
nucleus-nucleus collisions.Comment: 16 pages, 6 figures, a reference adde
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