Neutron electric dipole moment with external electric field method in lattice QCD

We discuss a possibility that the Neutron Electric Dipole Moment (NEDM) can be calculated in lattice QCD simulations in the presence of the CP violating $\theta$ term. In this paper we measure the energy difference between spin-up and spin-down states of the neutron in the presence of an uniform and static external electric field. We first test this method in quenched QCD with the RG improved gauge action on a $16^3\times 32$ lattice at $a^{-1}\simeq$ 2 GeV, employing two different lattice fermion formulations, the domain-wall fermion and the clover fermion for quarks, at relatively heavy quark mass $(m_{PS}/m_V \simeq 0.85)$. We obtain non-zero values of NEDM from calculations with both fermion formulations. We next consider some systematic uncertainties of our method for NEDM, using $24^3\times 32$ lattice at the same lattice spacing only with the clover fermion. We finally investigate the quark mass dependence of NEDM and observe a non-vanishing behavior of NEDM toward the chiral limit. We interpret this behavior as a manifestation of the pathology in the quenched approximation.Comment: LaTeX2e, 51 pages, 43 figures, uses revtex4 and graphicx, References and comments added, typos corrected, 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 $\theta$ 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

Neutron electric dipole moment from lattice QCD

We carry out a feasibility study for the lattice QCD calculation of the neutron electric dipole moment (NEDM) in the presence of the $\theta$ term. We develop the strategy to obtain the nucleon EDM from the CP-odd electromagnetic form factor $F_3$ at small $\theta$, in which NEDM is given by $\lim_{q^2\to 0}\theta F_3(q^2)/(2m_N)$ where $q$ is the momentum transfer and $m_N$ is the nucleon mass. We first derive a formula which relates $F_3$, a matrix element of the electromagnetic current between nucleon states, with vacuum expectation values of nucleons and/or the current. In the expansion of $\theta$, the parity-odd part of the nucleon-current-nucleon three-point function contains contributions not only from the parity-odd form factors but also from the parity-even form factors multiplied by the parity-odd part of the nucleon two-point function, and therefore the latter contribution must be subtracted to extract $F_3$. We then perform an explicit lattice calculation employing the domain-wall quark action with the RG improved gauge action in quenched QCD at $a^{-1}\simeq 2$ GeV on a $16^3\times 32\times 16$ lattice. At the quark mass $m_f a =0.03$, corresponding to $m_\pi/m_\rho \simeq 0.63$, we accumulate 730 configurations, which allow us to extract the parity-odd part in both two- and three-point functions. Employing two different Dirac $\gamma$ matrix projections, we show that a consistent value for $F_3$ cannot be obtained without the subtraction described above. We obtain $F_3(q^2\simeq 0.58 \textrm{GeV}^2)/(2m_N) =$ $-$0.024(5) $e\cdot$fm for the neutron and $F_3(q^2\simeq 0.58 \textrm{GeV}^2)/(2m_N) =$ 0.021(6) $e\cdot$fm for the proton.Comment: LaTeX2e, 43 pages, 42 eps figures, uses revtex4 and graphicx, comments added and typos corrected, final version to appear in Phys. Rev.

Detection of serum soluble markers of immune activation in rheumatoid arthritis

The mutual correlation among soluble CD4 (sCD4), soluble CD8 (sCD8), and soluble CD23 (sCD23) has not yet been studied in patients with rheumatoid arthritis (RA), although previous studies have demonstrated that certain soluble markers of immune activation are elevated in RA. Thus, we examined this correlation based on the serum levels of sCD4, sCD8 and sCD23, and that of their levels with other serum markers such as immunoglobulin (Ig) subtypes (IgG, IgM and IgA), IgM-rheumatoid factor (IgM-RF) and C-reactive protein (CRP) in 25 RA patients, sCD4 was not elevated, whereas both sCD8 and sCD23 increased in RA patients compared with the healthy controls; a majority of RA patients, in particular, showed a high sCD23 level. The level of sCD23 showed a correlation with that of IgM-RF, but not with those of IgG, IgM, IgA and CRP. Importantly, a high level of sCD23 was not always accompartied with that of sCD8. The independent change between sCD23 and sCD8 levels was also observed in a one-year follow-up study of the two RA patients. These findings indicate that B cells might be generally activated in RA, whereas T-cell activation in variable in each patient with RA, suggesting that sCD23 is a more indicative marker for the immune status of RA patients than sCD8 from the clinical aspects

The slow release of BMP-7 at a low dose accelerates dental implant healing in an osteopenic environment.

The aim of the present study was to investigate in vivo whether bone morphogenetic protein-7 (BMP-7) was able to promote and accelerate dental implant healing at a low dose in an osteopenic environment by using a delayed drug-release system. Skeletally mature Chinese goats, having physiologically osteopenic (osteoporotic-like) facial bones, served as an animal model. Dental implants were provided with a delayed-release drug-delivery system and BMP-7 was applied at three different dosages. The implants, inserted into healed extraction sockets, were removed 1, 2 and 3 weeks after surgery. Quantification of osseointegration and formation of new bone in the peri- implant space were measured histomorphometrically. Data revealed no evidence of any adverse drug effect at or near the implantation sites. After the first postoperative week, bone neoformation was minimal; after the second week, peri-implant bone formation appeared, particularly in the groups with low dosages of BMP-7. After 3 weeks, new-bone volume was the largest in the group with the lowest (near-physiological) dosage of BMP-7, also showing the highest efficacy of BMP-7. Other dosage or release modes were found to be significantly less effective. BMP-7 was highly efficacious in promoting and accelerating bone formation in the peri-implant space in a hostile osteopenic environment if released by a slow-mode mechanism over time at near physiological activities. Therefore, biological functionalisation of dental implants by a high-power osteogenic factor may improve their healing success in hostile bony environments (osteopenia, osteoporosis, bone atrophy etc.)