The equivariant K-theory of toric varieties

This paper contains two results concerning the equivariant K-theory of toric varieties. The first is a formula for the equivariant K-groups of an arbitrary affine toric variety, generalizing the known formula for smooth ones. In fact, this result is established in a more general context, involving the K-theory of graded projective modules. The second result is a new proof of a theorem due to Vezzosi and Vistoli concerning the equivariant K-theory of smooth (not necessarily affine) toric varieties.Comment: 12 page

A Welfare Analysis of Spectrum Allocation Policies

Analysis of spectrum allocation policies in the economics literature focuses on competitive bidding for wireless licenses. Auctions generating high bids, as in Germany and the UK, are identified as "successful," while those producing lower receipts, as in Switzerland and the Netherlands, are deemed "fiascoes." Yet, even full and costless extraction of license rents does not map directly to social welfare, because spectrum policies creating rents impose social costs. For example, rules favoring monopoly market structure predictably increase license values, but reduce welfare. This paper attempts to shift analytical focus to the relationship between spectrum policy (including license auctions) and efficiency in output markets. In cross-country comparisons of performance metrics in mobile telephone service markets, empirical estimates suggest that countries that auction licenses do not achieve lower prices or higher levels of output than other nations. Rather, countries allocating greater bandwidth to licensed operators and achieving more competitive market structures realize demonstrable social welfare benefits. These gains generally dominate efficiencies associated with license sales. Policies to increase auction revenues, such as reservation prices and subsidies for weak bidders, should be evaluated in this light.

Diquark in Nona-quark States

We study the nonaquark states $S^0(3115)$ and $S^+(3140)$ which are reported by KEK-PS (Phys.Lett. B597 (2004) 236; nucl-ex/0310018) by means of the quark model with diquark correlation. The nonaquark states form $\bf{1},\bf{8},\bf{10},\bar{\bf{10}},\bf{27},\bar{\bf{35}}$ SU(3) multiplets. The flavor wave functions of all the nonaquark states are constructed through the standard tensor technique. The mass spectrum is studied by using Gell-Mann-Okubo mass formula. Some nonaquark mass sum rules are obtained. We further investigate the decay of $S^0(3115)$ and $S^+(3140)$ under the assumption of "fall-apart" mechanism. It has been found that the main decay mode is $\Sigma NN$ rather than $\Lambda NN$ which is consistent with experiment. Also we have uniquely determine the flavor wave function of $S^0(3115)$ which belong to $\bf{27}$-plet with the quantum number $Y=2,I=1,I_z=-1$. Whereas the exotic states $S^+(3140)$ can belong to either $\bf{27}$-plet or $\bar{\bf{35}}$-plet. In the exact $SU(3)^{flavor}\times SU(3)^{color}\times SU(2)^{spin}$ limit, both $S^0(3115)$ and $S^+(3140)$ belong to ${\bf 27}$-plet with negative parity. We predict that its flavor structure can be determined by measuring the branch fractions of its decay channels. The experiments to check this prediction are expected.Comment: 23 pages, 8 figures, to appear in Phys. Rev.

Higgs Triplets, Decoupling, and Precision Measurements

Electroweak precision data has been extensively used to constrain models containing physics beyond that of the Standard Model. When the model contains Higgs scalars in representations other than SU(2) singlets or doublets, and hence rho not equal to one at tree level, a correct renormalization scheme requires more inputs than the three needed for the Standard Model. We discuss the connection between the renormalization of models with Higgs triplets and the decoupling properties of the models as the mass scale for the scalar triplet field becomes much larger than the electroweak scale. The requirements of perturbativity of the couplings and agreement with electroweak data place strong restrictions on models with Higgs triplets. Our results have important implications for Little Higgs type models and other models with rho not equal to one at tree level.Comment: 23 page

Phytoestrogen Biological Actions on Mammalian Reproductive System and Cancer Growth

Phytoestrogens are a family of diverse polyphenolic compounds derived from nature plant that structurally or functionally mimic circulating estrogen in the mammalian reproductive system. They induce estrogenic and anti-estrogenic effects in the brain-pituitary-gonad axis (a principal endocrine system involving in reproductive regulation) and peripheral reproductive organs. The dichotomy of phytoestrogen-mediated actions elucidates that they play the biological activities via complex mechanisms and belong to various chemical classes. In comparison with their unobvious physiological functions in normal reproductive tissues, there are increasing investigations showing that phytoestrogen induces significant inhibitory effects on the growth of breast and ovarian cancers through different signaling pathways. This review summarized the results of the previous studies regarding principal signaling transductions for mediating the growth of the ovarian and breast cancers. Phytoestrogen potentially modulates the signaling molecules via: (1) blocking the nuclear and membrane estrogen receptors (ER), (2) interfering with the growth factor receptor, (3) inhibiting the G protein-coupled receptor in ER-deficient cells, (4) activating apoptosis and nullifying anti-apoptotic signals

Evidence for line nodes in the energy gap of the overdoped Ba(Fe1−x_{1-x}Cox_{x})2_{2}As2_{2} from low-temperature specific heat measurements

Low-temperature specific heat (SH) is measured on Ba(Fe$_{1-x}$Co$_{x}$)$_2$As$_2$ single crystals in a wide doping region under different magnetic fields. For the overdoped sample, we find the clear evidence for the presence of $T^2$ term in the data, which is absent both for the underdoped and optimal doped samples, suggesting the presence of line nodes in the energy gap of the overdoped samples. Moreover, the field induced electron specific heat coefficient $\Delta\gamma(H)$ increases more quickly with the field for the overdoped sample than the underdoped and optimal doped ones, giving another support to our arguments. Our results suggest that the superconducting gap(s) in the present system may have different structures strongly depending on the doping regions.Comment: 5 pages, 4 figure