Summary of the Structure Functions and Low-x working group

We report a summary of the structure function working group which covers a wide range of the recent results from HERA, Tevatron, RHIC, and JLab experiments, and many theoretical issues from low x to high x.Comment: 20 pages, presented at 13th International Workshop on Deep Inelastic Scattering (DIS 05), Madison, Wisconsin, 27 Apr - 1 May 200

Nuclear Modification to Parton Distribution Functions and Parton Saturation

We introduce a generalized definition of parton distribution functions (PDFs) for a more consistent all-order treatment of power corrections. We present a new set of modified DGLAP evolution equations for nuclear PDFs, and show that the resummed $\alpha_s A^{1/3}/Q^2$-type of leading nuclear size enhanced power corrections significantly slow down the growth of gluon density at small-$x$. We discuss the relation between the calculated power corrections and the saturation phenomena.Comment: 4 pages, to appear in the proceedings of QM200

Projected Hartree Fock Theory as a Polynomial Similarity Transformation Theory of Single Excitations

Spin-projected Hartree-Fock is introduced as a particle-hole excitation ansatz over a symmetry-adapted reference determinant. Remarkably, this expansion has an analytic expression that we were able to decipher. While the form of the polynomial expansion is universal, the excitation amplitudes need to be optimized. This is equivalent to the optimization of orbitals in the conventional projected Hartree-Fock framework of non-orthogonal determinants. Using the inverse of the particle-hole expansion, we similarity transform the Hamiltonian in a coupled-cluster style theory. The left eigenvector of the non-hermitian Hamiltonian is constructed in a similar particle-hole expansion fashion, and we show that to numerically reproduce variational projected Hartree-Fock results, one needs as many pair excitations in the bra as the number of strongly correlated entangled pairs in the system. This single-excitation polynomial similarity transformation theory is an alternative to our recently presented double excitation theory, but supports projected Hartree-Fock and coupled cluster simultaneously rather than interpolating between them

Considering Macroeconomic Indicators in the Food versus Fuel Issues

In this study, a Structural Vector Autoregression model (SVAR) is employed to decompose how supply/demand structural shocks affect food and fuel prices within fuel and corn markets. Results indicate that the relative importance of each structural shock in explaining the variation of corn prices is different. Our findings support the hypothesis that corn prices increase as a response to those positive demand shocks in the short run, while in the long run, global competitive agricultural commodities markets as well as positive supply shocks respond to commodity price shocks, restoring prices to its long-run trends. In conclusion, fundamental market forces of demand and supply as well as real economic aggregated demand shocks were the main contributors of the 2007-2008 food price spike.Food, fuel, Food Consumption/Nutrition/Food Safety, Resource /Energy Economics and Policy,

Projected Coupled Cluster Theory: Optimization of cluster amplitudes in the presence of symmetry projection

Methods which aim at universal applicability must be able to describe both weak and strong electronic correlation with equal facility. Such methods are in short supply. The combination of symmetry projection for strong correlation and coupled cluster theory for weak correlation offers tantalizing promise to account for both on an equal footing. In order to do so, however, the coupled cluster portion of the wave function must be optimized in the presence of the symmetry projection. This paper discusses how this may be accomplished, and shows the importance of doing so for both the Hubbard model Hamiltonian and the molecular Hamiltonian, all with a computational scaling comparable to that of traditional coupled cluster theory.Comment: revised versio

Projected Coupled Cluster Theory

Coupled cluster theory is the method of choice for weakly correlated systems. But in the strongly correlated regime, it faces a symmetry dilemma, where it either completely fails to describe the system, or has to artificially break certain symmetries. On the other hand, projected Hartree-Fock theory captures the essential physics of many kinds of strong correlations via symmetry breaking and restoration. In this work, we combine and try to retain the merits of these two methods by applying symmetry projection to broken symmetry coupled cluster wavefunctions. The non-orthogonal nature of states resulting from the application of symmetry projection operators furnishes particle-hole excitations to all orders, thus creating an obstacle for the exact evaluation of overlaps. Here we provide a solution via a disentanglement framework theory that can be approximated rigorously and systematically. Results of projected coupled cluster theory are presented for molecules and the Hubbard model, showing that spin projection significantly improves unrestricted coupled cluster theory while restoring good quantum numbers. The energy of projected coupled cluster theory reduces to the unprojected one in the thermodynamic limit, albeit at a much slower rate than projected Hartree-Fock.Comment: Submitted to JCP. Extra figures appear in the ancillary fil

Ion-beam-enhanced adhesion in the electronic stopping region

The use of ion beams in the electronic stopping region to improve the adhesion of insulators to other materials is described. In particular, the bonding of Au films to Teflon, ferrite, and SiO2 was improved by bombarding them with He and Cl, respectively. Improvements in bonding were also observed for Au on glass, Au and Cu on sapphire, and Si3N4 on Si. The mechanism is apparently associated with sputtering and track forming processes occurring in the electronic stopping region. Some applications are discussed

An Ethanol Blend Wall Shift is Prone to Increase Petroleum Gasoline Demand

The US Environmental Protection Agency announced a waiver allowing an increase in the Fuel-Ethanol blend limit (the “blend wall” ) from 10% (E10) to 15% (E15) on October,2010.Justifications for the waiver are reduced vehicle fuel prices and less consumption of petroleum gasoline, leading to energy security. In this paper, employing Monte Carlo simulations and Savitzky-Golay smoothing filter, an empirical study examines this waiver revealing an anomaly where a relaxation of this blend wall elicits a demand response. Under a wide range of elasticities, this demand response can actually increase the consumption of petroleum gasoline and thus lead to greater energy insecurity. The economics supporting this result and associated policy implications are developed and discussed.Blend wall, Energy security, Ethanol, Resource /Energy Economics and Policy,