Phenomenological Constraints on Anomaly-Free Dark Matter Models

We study minimal benchmark models of dark matter with an extra anomaly-free U(1)' gauge boson Z'. We find model parameters that give rise to the correct cosmological dark matter density while evading the latest direct detection searches for dark matter scattering produced by the XENON1T experiment, including the effects of Z-Z' mixing. We also find regions of parameter space that evade the constraints from LHC measurements of dileptons and dijets, precision electroweak measurements, and LHC searches for monojet events with missing transverse energy. We study two benchmark Z' models with Y-sequential couplings to quarks and leptons, one with a vector-like coupling to the dark matter particle and one with an axial dark matter coupling. The vector-like model is extremely tightly constrained, with only a narrow allowed strip where $m_\chi \simeq M_{Z'}/2$, and the axial model is excluded within the parameter range studied. We also consider two leptophobic Z$^\prime$ benchmark models, finding again narrow allowed strips where $m_\chi \simeq M_{Z'}/2$ as well as more extended regions where $\log_{10} (m_\chi/ {\rm GeV}) \gtrsim 3.2$.Comment: 29 pages, 18 figures, 0 anomalie

Anomaly-Free Dark Matter Models are not so Simple

We explore the anomaly-cancellation constraints on simplified dark matter (DM) models with an extra U(1)$^\prime$ gauge boson $Z'$. We show that, if the Standard Model (SM) fermions are supplemented by a single DM fermion $\chi$ that is a singlet of the SM gauge group, and the SM quarks have non-zero U(1)$^\prime$ charges, the SM leptons must also have non-zero U(1)$^\prime$ charges, in which case LHC searches impose strong constraints on the $Z'$ mass. Moreover, the DM fermion $\chi$ must have a vector-like U(1)$^\prime$ coupling. If one requires the DM particle to have a purely axial U(1)$^\prime$ coupling, which would be the case if $\chi$ were a Majorana fermion and would reduce the impact of direct DM searches, the simplest possibility is that it is accompanied by one other new singlet fermion, but in this case the U(1)$^\prime$ charges of the SM leptons still do not vanish. This is also true in a range of models with multiple new singlet fermions with identical charges. Searching for a leptophobic model, we then introduce extra fermions that transform non-trivially under the SM gauge group. We find several such models if the DM fermion is accompanied by two or more other new fermions with non-identical charges, which may have interesting experimental signatures. We present benchmark representatives of the various model classes we discuss.Comment: 19 pages, 0 figures, this v2 matches version accepted for publicatio

The impact of grazing cattle on soil physical properties and nutrient concentrations in overland flow from pasture, Part B

This report has been prepared as part of the Environmental Research Technological Development and Innovation Programme 2000–2006. The programme is financed by the Irish Government under the National Development Plan 2000–2006.End of project reportThe loss of nutrients from agricultural land to water bodies is a serious concern in many countries. To gain information on the contribution of grazing animals to diffuse nutrient losses from pasture areas to water, this study looked at the impact of cattle on nutrient concentrations in overland flow and on soil hydrology (bulk density, macroporosity and resistance to penetration). Rainfall simulations to produce overland flow were conducted and soil physical measurements were taken on experimental plots assigned to one of two treatments: 1) cattle had unrestricted access to the plot; 2) cattle could graze the plot but they could neither walk on the plot area nor deposit excrements on it. Areas to which the cattle had free access were characterised by 57%-83% lower macroporosity, by 8%-17% higher bulk density and by 27%-50% higher resistance to penetration than areas from which the cattle were excluded. The nutrients in overland flow from grassland that were affected by the presence of grazing animals were mainly the particulate nitrogen, the organic phosphorus and the potassium concentrations. Overall, the presence of cattle had a longer lasting effect on the soil hydrological parameters measured than on the nutrient concentrations in overland flow.Environmental Protection Agenc

A legacy for chemistry education

The Royal Society of Chemistry (RSC) has a longstanding reputation for providing innovative and up to date support for chemical science education – from primary, through to higher education and beyond. The RSC is continually developing easily accessible resources and events to help meet the needs of changing curricula and the skills required by employers.At A-level and degree level the focus is on increasing the numbers of students studying chemistry and the chemical sciences in order to educate the next generation of science-based professionals. The Chemistry for our Future (CFOF) programme was established with the aim of ensuring a strong and sustainable future for chemical sciences in higher education by increasing the aspirations of students, promoting the chemical sciences at all levels and improving the school to university transition

Variations in functional relationships between amplitude and phase images

The objective of this research is to study the functional relationship between amplitude and phase images, using a sinusoidal test function. Amplitude and phase sine wave gratings were produced and scanned. It was found that the phase image closely reproduces the amplitude image for low spatial frequencies, but the accuracy of reproduction falls off at high spatial frequencies

A language based on the Pi-calculus

The exponential increase in the volume and sensitivity of data transmitted over electronic media has resulted in a corresponding increase in attempts to secure these inherently insecure transmissions. Numerous networking protocols and associated mechanisms have been used but implementing distributed systems is a notoriously error prone exercise. Attempts to ensure the relevant properties are present in distributed systems can be made by the application of formal methods. However this application of formal methods is made to the specification of a distributed system, not its actual implementation. Typically, a wide gulf exists between the specification of a distributed system and its actual implementation, and this gulf can result in the introduction of potentially devastating errors. A method of bridging this gulf is required in order that the application of formal methods to distributed systems can become more widespread and more accessible. We propose a general purpose programming language that is based on one of the more popular formal notations used to specify distributed systems, the 7r-calculus With this approach we allow the integration of complex sequential computations into 7r-calculus specifications of distributed systems to produce systems that are capable of execution in a distributed and concurrent fashion. The implementation of this proposal is facilitated by designing the language such that fragments of Java code can be integrated into a 7r-calculus framework

Is the Bar Meeting Its Ethical Responsibilities?

Our society depends to a large extent on lawyers to assure all citizens the protection and advantages of the law. The legal profession itself ? through its largest national organization, the American Bar Association, and through most state bars which adopt or enforce disciplinary rules for lawyers ? has chosen, in the canons quoted above, to impose on itself the ethical responsibility of making competent legal services available to all those who need them. Society has accepted the profession\u27s position, and has subjected the ethical conduct of lawyers to little government interference or supervision