1,833 research outputs found
Electromagnetic and spin polarisabilities in lattice QCD
We discuss the extraction of the electromagnetic and spin polarisabilities of
nucleons from lattice QCD. We show that the external field method can be used
to measure all the electromagnetic and spin polarisabilities including those of
charged particles. We then turn to the extrapolations required to connect such
calculations to experiment in the context of finite volume chiral perturbation
theory. We derive results relevant for lattice simulations of QCD,
partially-quenched QCD and quenched QCD. Our results for the polarisabilities
show a strong dependence on the lattice volume and quark masses, typically
differing from the infinite volume limit by ~10% for current lattice volumes
and quark masses.Comment: Minor change
Two-photon decay of the neutral pion in lattice QCD
We perform non-perturbative calculation of the \pi^0 to {\gamma}{\gamma}
transition form factor and the associated decay width using lattice QCD. The
amplitude for two-photon final state, which is not an eigenstate of QCD, is
extracted through an Euclidean time integral of the relevant three-point
function. We utilize the all-to-all quark propagator technique to carry out
this integral as well as to include the disconnected quark diagram
contributions. The overlap fermion formulation is employed on the lattice to
ensure exact chiral symmetry on the lattice. After examining various sources of
systematic effects except for possible discretization effect, we obtain
\Gamma=7.83(31)(49) eV for the pion decay width, where the first error is
statistical and the second is our estimate of the systematic error.Comment: 5 pages, 4 figures. Changes made addressing to referee's comments,
version accepted by PR
Full QCD calculation of neutron electric dipole moment with the external electric field method
We have calculated the neutron electric dipole moment (NEDM) in the presence
of the CP violating term in lattice QCD with 2-flavor dynamical clover
quarks, using the external electric field method. Accumulating a large number
of statistics by the averages over 16 different source points and over forward
and backward nucleon propagators, we have obtained non-zero signals of neutron
and proton EDM beyond one standard deviation at each quark mass in full QCD. We
have investigated the quark mass dependence of nucleon EDM in full QCD, and
have found that nucleon EDM in full QCD does not decrease toward the chiral
limit, as opposed to the theoretical expectation. We briefly discuss possible
reasons for this behavior.Comment: 27 pages, 15 figures, 2 tables, reference added, tyops corrected,
published versio
Histological and immunohistochemical observation of the furcation area formation with the subpulpal lobus of rat molar.
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