Counting similarities between tetraquark and mesonic/gluonic operators

After the study of the preclusion of exotic meson states in large-$N_c$ limit QCD, combining Weinberg's opposite proposal, we get different counting orders for a tetraquark operator to create or destroy an one-tetraquark state. Meanwhile, by comparing tetraquark operator with the mesonic and gluonic operators, we find that tetraquark operators are similar with mesonic and gluonic operators in the counting. Furthermore, we find a mixing of different kinds of operators.Comment: 4 page

Exact coefficients for higher dimensional operators with sixteen supersymmetries

We consider constraints on higher dimensional operators for supersymmetric effective field theories. In four dimensions with maximal supersymmetry and SU(4) R-symmetry, we demonstrate that the coefficients of abelian operators F^n with MHV helicity configurations must satisfy a recursion relation, and are completely determined by that of F^4. As the F^4 coefficient is known to be one-loop exact, this allows us to derive exact coefficients for all such operators. We also argue that the results are consistent with the SL(2,Z) duality symmetry. Breaking SU(4) to Sp(4), in anticipation for the Coulomb branch effective action, we again find an infinite class of operators whose coefficient that are determined exactly. We also consider three-dimensional N=8 as well as six-dimensional N=(2,0),(1,0) and (1,1) theories. In all cases, we demonstrate that the coefficient of dimension-six operator must be proportional to the square of that of dimension-four.Comment: typos corrected, minor modificatio

Direct Observation of Long-Term Durability of Superconductivity in YBa2_2Cu3_3O7_7-Ag2_2O Composites

We report direct observation of long-term durability of superconductivity of several YBa$_2$Cu$_3$O$_7$-Ag$_2$O composites that were first prepared and studied almost 14 years ago [J. J. Lin {\it et al}., Jpn. J. Appl. Phys. {\bf 29}, 497 (1990)]. Remeasurements performed recently on both resistances and magnetizations indicate a sharp critical transition temperature at 91 K. We also find that such long-term environmental stability of high-temperature superconductivity can only be achieved in YBa$_2$Cu$_3$O$_7$ with Ag$_2$O addition, but not with pure Ag addition.Comment: to be published in Jpn. J. Appl. Phy

Synthesis and characterization of chiral imidazolinones

The commercial application of imidazolinone derivatives can be found in herbicides where they inhibit acetolactate synthase (ALS; EC 4.1.3.18; also known as acetohydroxyacid synthase). The imidazolinone class of herbicides have the advantage of long term activity and low mammalian toxicity. Another application of imidazolinone derivatives is in the preparation of a-alkyl-amino acids. The objective of this investigation was to explore the asymmetric synthesis of imidazolinones through the condensation of a variety of imidate ethyl esters and ccamino acids. Furthermore, it was of interest to characterize the chiral properties of a series of imidazolinone derivatives for future investigation. In this research project, the method of synthesis of imidazolinones was applied and modified from the method which was established in the work of Kidwai, A. Q. and Devasia. G. M. in 1962. (J. Org. Chem. 1962, 27, 4527) Their synthetic work was only successful with aromatic amino acids and benzimidates, therefore, an attempt was made to generalize the preparation of imidazolinones to include nonaromatic systems in this study