SU(3) lattice QCD study for octet and decuplet baryon spectra

The spectra of octet and decuplet baryons are studied using SU(3) lattice QCD at the quenched level. As an implementation to reduce the statistical fluctuation, we employ the anisotropic lattice with $O(a)$ improved quark action. In relation to $\Lambda(1405)$, we measure also the mass of the SU(3) flavor-singlet negative-parity baryon, which is described as a three quark state in the quenched lattice QCD, and its lowest mass is measured about 1.6 GeV. Since the experimentally observed negative-parity baryon $\Lambda(1405)$ is much lighter than 1.6 GeV, $\Lambda(1405)$ may include a large component of a $N \bar K$ bound state rather than the three quark state. The mass splitting between the octet and the decuplet baryons are also discussed in terms of the current quark mass.Comment: 8 pages, 3 figures, proceeding of "International Symposium on Hadron and Nuclei" at Yonsei Univ., Seoul, Korea 20-22 Feb. 200

A near deterministic linear optical CNOT gate

We show how to construct a near deterministic CNOT using several single photons sources, linear optics, photon number resolving quantum non-demolition detectors and feed-forward. This gate does not require the use of massively entangled states common to other implementations and is very efficient on resources with only one ancilla photon required. The key element of this gate are non-demolition detectors that use a weak cross-Kerr nonlinearity effect to conditionally generate a phase shift on a coherent probe, if a photon is present in the signal mode. These potential phase shifts can then be measured using highly efficient homodyne detection.Comment: 4 pages, 3 figure

Negative-Parity Baryons in Quenched Anisotropic Lattice QCD

We study negative-parity baryon spectra in quenched anisotropic lattice QCD. The negative-parity baryons are measured as the parity partner of the ground-state baryons. In addition to the flavor octet and decuplet baryons, we pay much attention to the flavor-singlet negative-parity baryon as a three-quark state and compare it with the Lambda(1405) baryon. Numerical results of the flavor octet and decuplet negative-parity baryon masses are close to experimental values of lowest-lying negative-parity baryons, while the flavor-singlet baryon is much heavier than Lambda(1405). This indicates that the Lambda(1405) would be a multi-quark state such as the N-Kbar molecule rather than the flavor-singlet 3 quark state.Comment: 4 pages, 4 figs. Talk given at 16th International Conference on Particles and Nuclei (PANIC 02), Osaka, Japan, 30 Sep - 4 Oct 200

Spin 3/2 Penta-quarks in anisotropic lattice QCD

A high-precision mass measurement for the pentaquark (5Q) Theta^+ in J^P=3/2^{\pm} channel is performed in anisotropic quenched lattice QCD using a large number of gauge configurations as N_{conf}=1000. We employ the standard Wilson gauge action at beta=5.75 and the O(a) improved Wilson (clover) quark action with kappa=0.1210(0.0010)0.1240 on a 12^3 \times 96 lattice with the renormalized anisotropy as a_s/a_t = 4. The Rarita-Schwinger formalism is adopted for the interpolating fields. Several types of the interpolating fields with isospin I=0 are examined such as (a) the NK^*-type, (b) the (color-)twisted NK^*-type, (c) a diquark-type. The chiral extrapolation leads to only massive states, i.e., m_{5Q} \simeq 2.1-2.2 GeV in J^P=3/2^- channel, and m_{5Q} = 2.4-2.6 GeV in J^P=3/2^+ channel. The analysis with the hybrid boundary condition(HBC) is performed to investigate whether these states are compact 5Q resonances or not. No low-lying compact 5Q resonance states are found below 2.1GeV.Comment: 15 pages, 6 figures, 4 table

Synthesis of Cobalamin Analogues Using Enzymatic and Chemical Modification Methods, and Subsequent Identification of Cobalamin Localisation in a Variety of Organisms

Cobalamin, also known as vitamin B12, is an essential nutrient for many different organisms including mammals, fish, birds, nematodes, and a variety of bacteria. However, cobalamin is only synthesised by a few bacteria and archaea. Organisms that cannot synthesise cobalamin de novo must obtain it from their diet. In humans, the cobalamin uptake mechanism has been studied in detail, but in many organisms, such as Caenorhabditis elegans, no method of transport has been defined, and their need for cobalamin is recognised by a cobalamin deficiency phenotype. Corrin ring modified fluorescent analogues of cobyric acid and ribose conjugated fluorescent analogues of cobalamin were synthesised in order to follow the uptake and localisation of these corrinoids in a variety of organisms. Both the C5 corrin-ring modified and the ribose conjugated analogues were absorbed by Salmonella enterica, using the B12 uptake system (Btu) and could be converted into active coenzyme forms. The imaging of these fluorescent analogues enabled the identification of the coelomocytes in C. elegans as a possible storage cell for cobalamin. However, the C5 cobyric acid analogue was not recognised which suggests that the C. elegans cobalamin transport mechanism is specific for complete corrinoid molecules. Lepidium sativum, garden cress, was shown to take up both cobalamin analogues from the roots and store it in the vacuoles of the cotyledons in seedlings, even though plants have no cobalamin requirement. In contrast, Arabidopsis thaliana did not transport any of the cobalamin analogues. Cobalamin deficiency has been implicated in impeding disease progression in a number of diseases, such as tuberculosis. The Mycobacterium tuberculosis cobalamin uptake protein, BacA, has only recently been identified, and there is still much to learn about the relationship between M. tuberculosis and cobalamin. Incubations of a cobalamin dependent strain of M. tuberculosis, ?metE, with a selection of cobalamin biosynthesis intermediates showed that cobyric acid is the earliest intermediate to be taken up and converted into the cofactor form. The C5 corrin ring modified cobyric acid fluorescent analogue is also capable of rescuing this ?metE strain, and is taken up faster than the ribose conjugated cobalamin analogue. Overall, the research outlined in this thesis demonstrates that fluorescent corrinoid analogues can be used to follow the journey of cobalamin in a broad range of different organisms and systems