Four-Lepton Resonance at the Large Hadron Collider

A spin-1 weakly interacting vector boson, Z', is predicted by many new physics theories. Searches at colliders for such a Z' resonance typically focus on lepton-antilepton or top-antitop events. Here we present a novel channel with a Z' resonance that decays to 4 leptons, but not to 2 leptons, and discuss its possible discovery at the Large Hadron Collider. This baryonic gauge boson is well motivated in a supersymmetry framework.Comment: Version to appear in PR

Lightest Neutralino in Extensions of the MSSM

We study neutralino sectors in extensions of the MSSM that dynamically generate the mu-term. The extra neutralino states are superpartners of the Higgs singlets and/or additional gauge bosons. The extended models may have distinct lightest neutralino properties which can have important influences on their phenomenology. We consider constraints on the lightest neutralino from LEP, Tevatron, and (g-2)_mu measurements and the relic density of the dark matter. The lightest neutralino can be extremely light and/or dominated by its singlino component which does not couple directly to SM particles except Higgs doublets.Comment: 17 pages, revtex4, 5 figure

Muon Anomalous Magnetic Moment in a Supersymmetric U(1)' Model

We study the muon anomalous magnetic moment a_\mu = (g_\mu - 2)/2 in a supersymmetric U(1)' model. The neutralino sector has extra components from the superpartners of the U(1)' gauge boson and the extra Higgs singlets that break the U(1)' symmetry. The theoretical maximum bound on the lightest neutralino mass is much smaller than that of the Minimal Supersymmetric Standard Model (MSSM) because of the mixing pattern of the extra components. In a U(1)' model where the U(1)' symmetry is broken by a secluded sector (the S-model), tan\beta is required to be < 3 to have realistic electroweak symmetry breaking. These facts suggest that the a_\mu prediction may be meaningfully different from that of the MSSM. We evaluate and compare the muon anomalous magnetic moment in this model and the MSSM and discuss the constraints on tan\beta and relevant soft breaking terms. There are regions of the parameter space that can explain the experimental deviation of a_\mu from the Standard Model calculation and yield an acceptable cold dark matter relic density without conflict with collider experimental constraints.Comment: Version to appear in Physics Letters B. 12 pages, revtex4, 4 figure

Solution to the B -> pi K Puzzle in a Flavor-Changing Z' Model

Recent experiments suggest that certain B -> pi K branching ratios are inconsistent with the standard model expectations. We show that a flavor-changing Z' provides a solution to the problem. Electroweak penguin amplitudes are enhanced by the Z' boson for select parameters. We discuss implications for the Z' mass and its couplings to the standard model fermions. We also show that the solution is consistent with constraints from the CP asymmetries of the B -> phi K_S decay.Comment: 7 pages, 5 figures, to be submitted to Phys. Lett. B; references update

Organization of disaster aid delivery: spending your donations

This paper examines how different organizational structures in disaster aid delivery affect house aid quality. We analyze three waves of survey data on fishermen and fishing villages in Aceh, Indonesia following the tsunami. We categorize four organizational structures based on whether and to whom donors contract aid implementation. Compared to bilateral contracting between donors and implementers, donors that vertically integrate and do their own implementation offer the highest quality housing as rated by village heads and have fewer counts of faults, such as leaky roofs and cracked walls, as reported by fishermen. However, they shade in quality as they lose dominance as the leading aid agency in a village. Domestic implementers and the government agency that was responsible for significant portions of aid delivery provide significantly lower quality aid. We also examine how the imposition of shared ownership, the primary social agenda for boat aid agencies, affects boat aid quality. We find that village and fishing leaders steer poor quality boats towards those whom shared ownership were imposed upon, often lower status fishermen

Humic substances removal by activated carbon

Humic substances are a major concern to the water treatment industry because they can cause odor and color problems and are potentially toxic and/or cancinogenic. A commercial humic acid and fulvic acid extracted from peat were used to evaluate the removal or humic substances by various activated carbons. Different analytical methods were investigated to measure the concentration of humic substances and their chloroform formation potential. Total organic carbon measurement and ultraviolet/visible absorbance correlate well with the chloroform formation potential of humic substances. Pore volumes of activated carbon in pores between 100 and 500 Å radius were correlated with adsorption capacity. A decrease of pH in solution, lower molecular weight fractions of humic substances, smaller carbon particles, and presence of soluble alum were found to increase the carbon adsorption. Chemical pretreatment with alum increased the adsorption capacity of carbon almost threefold. This increase of adsorption capacity is probably because of the removal of weakly- or non-adsorbable humic substances by alum coagulation. The presence of soluble alum in the solution also enhances the adsorbability of humic substances. The application of a developed mathematical model to predict the performance of the carbon bed for the adsorption of humic substances was successful. Model parameter estimation techniques and model verification were evaluated and the applicability of the model was verified. In general, this model is sensitive to values of adsorption capacity of activated carbon and the surface diffusion coefficient was also correlated with the adsorption capacity. The higher the adsorption capacity, the lower the diffusion coefficient. Based on the model predictions, the empty bed contact time of the carbon bed and the influent concentrations were the two most important factors in designing a carbon bed for humic substances removal.U.S. Department of the InteriorU.S. Geological SurveyOpe

A Functional Imaging Study of Cooperation in Two-Person reciprocal Exchange

Cooperation between individuals requires the ability to infer each other’s mental states to form shared expectations over mutual gains and make cooperative choices that realize these gains. From evidence that the ability for mental state attribution involves the use of prefrontal cortex, we hypothesize that this area is involved in integrating theory-of-mind processing with cooperative actions. We report data from a functional MRI experiment designed to test this hypothesis. Subjects in a scanner played standard two-person ‘‘trust and reciprocity’’ games with both human and computer counterparts for cash rewards. Behavioral data shows that seven subjects consistently attempted cooperation with their human counterpart. Within this group prefrontal regions are more active when subjects are playing a human than when they are playing a computer following a fixed (and known) probabilistic strategy. Within the group of five noncooperators, there are no significant differences in prefrontal activation between computer and human conditions.Neuroeconomics; Exchange; Trust; Theory-of-Mind; functional Imaging of brain

Long Range Hops and the Pair Annihilation Reaction A+A->0: Renormalization Group and Simulation

A simple example of a non-equilibrium system for which fluctuations are important is a system of particles which diffuse and may annihilate in pairs on contact. The renormalization group can be used to calculate the time dependence of the density of particles, and provides both an exact value for the exponent governing the decay of particles and an epsilon-expansion for the amplitude of this power law. When the diffusion is anomalous, as when the particles perform Levy flights, the critical dimension depends continuously on the control parameter for the Levy distribution. The epsilon-expansion can then become an expansion in a small parameter. We present a renormalization group calculation and compare these results with those of a simulation.Comment: As-published version; two significant errors fixed, two references adde