Photon Structure and Quantum Fluctuation

Photon structure derives from quantum fluctuation in quantum field theory to fermion and anti-fermion, and has been an experimentally established feature of electrodynamics since the discovery of the positron. In hadronic physics, the observation of factorisable photon structure is similarly a fundamental test of the quantum field theory Quantum Chromodynamics (QCD). An overview of measurements of hadronic photon structure in e+e- and ep interactions is presented, and comparison made with theoretical expectation, drawing on the essential features of photon fluctuation into quark and anti-quark in QCD.Comment: 29 pages, 15 figures, to appear in Philosophical Transactions of the Royal Society of London (Series A: Mathematical, Physical and Engineering Sciences

Notes on the integration of numerical relativity waveforms

A primary goal of numerical relativity is to provide estimates of the wave strain, $h$, from strong gravitational wave sources, to be used in detector templates. The simulations, however, typically measure waves in terms of the Weyl curvature component, $\psi_4$. Assuming Bondi gauge, transforming to the strain $h$ reduces to integration of $\psi_4$ twice in time. Integrations performed in either the time or frequency domain, however, lead to secular non-linear drifts in the resulting strain $h$. These non-linear drifts are not explained by the two unknown integration constants which can at most result in linear drifts. We identify a number of fundamental difficulties which can arise from integrating finite length, discretely sampled and noisy data streams. These issues are an artifact of post-processing data. They are independent of the characteristics of the original simulation, such as gauge or numerical method used. We suggest, however, a simple procedure for integrating numerical waveforms in the frequency domain, which is effective at strongly reducing spurious secular non-linear drifts in the resulting strain.Comment: 23 pages, 10 figures, matches final published versio

Risk factor for footpad dermatitis and hock burns in broiler chickens

Footpad dermatitis (FPD) and hock burn (HB) are a major welfare concern in broiler chicken farming. In general, foot lesions are linked to poor environmental conditions. Ulcers caused by advanced lesions can negatively affect the gait of the birds, with effects on the welfare of animals, including, in the worst cases, inability to reach the feed or water. FPD and HB score data were collected manually at two broiler farms across Europe, during welfare assessments performed within the EU-PLF (Precision Livestock Farming) project, which is supported by the European Commission. This ongoing project aims to create "added value" for the farmer through the application of sensors and information technology at farm level. On those broiler farms, a number of variables such as temperature, relative humidity, ventilation rate, bird weight, light schedule, and feed and water consumption rates are measured automatically. The welfare of the chickens was assessed three times per cycle (at week 3, 4 and 5), scoring FPD, HB, gait score, cleanliness of the birds and litter quality. Data analysis was performed by combining data from the welfare assessments with environmental data collected by the automatic monitoring systems. The analysis showed that FPD and HB were more frequent when the flock was exposed to poor environmental conditions for prolonged periods of time. As environmental conditions can be measured continuously, and the risk factor for FPD and HB increases with poor environmental conditions, there is potential to develop a detection and control system for foot and hock lesions.</p

Superhumps in Cataclysmic Binaries. XXV. q_crit, epsilon(q), and Mass-Radius

We report on successes and failures in searching for positive superhumps in cataclysmic variables, and show the superhumping fraction as a function of orbital period. Basically, all short-period systems do, all long-period systems don't, and a 50% success rate is found at P_orb=3.1+-0.2 hr. We can use this to measure the critical mass ratio for the creation of superhumps. With a mass-radius relation appropriate for cataclysmic variables, and an assumed mean white-dwarf mass of 0.75 M_sol, we find a mass ratio q_crit=0.35+-0.02. We also report superhump studies of several stars of independently known mass ratio: OU Virginis, XZ Eridani, UU Aquarii, and KV UMa (= XTE J1118+480). The latter two are of special interest, because they represent the most extreme mass ratios for which accurate superhump measurements have been made. We use these to improve the epsilon(q) calibration, by which we can infer the elusive q from the easy-to-measure epsilon (the fractional period excess of P_superhump over P_orb). This relation allows mass and radius estimates for the secondary star in any CV showing superhumps. The consequent mass-radius law shows an apparent discontinuity in radius near 0.2 M_sol, as predicted by the disrupted magnetic braking model for the 2.1-2.7 hour period gap. This is effectively the "empirical main sequence" for CV secondaries.Comment: PDF, 45 pages, 9 tables, 12 figures; accepted, in press, to appear November 2005, PASP; more info at http://cba.phys.columbia.edu

Wedgebox analysis of four-lepton events from neutralino pair production at the LHC

`Wedgebox' plots constructed by plotting the di-electron invariant mass versus the di-muon invariant mass from pp -> e^+e^- mu^+ mu^- + missing energy signature LHC events. Data sets of such events are obtained across the MSSM input parameter space in event-generator simulations, including cuts designed to remove SM backgrounds. Their study reveals several general features: (1)Regions in the MSSM input parameter space where a sufficient number of events are expected so as to be able to construct a clear wedgebox plot are delineated. (2)The presence of box shapes on a wedgebox plot either indicates the presence of heavy Higgs bosons decays or restricts the location to a quite small region of low \mu and M_2 values \lsim 200 GeV, a region denoted as the `lower island'. In this region, wedgebox plots can be quite complicated and change in pattern rather quickly as one moves around in the (\mu, M_2) plane. (3)Direct neutralino pair production from an intermediate Z^{0*} may only produce a wedge-shape since only \widetilde{\chi}_2^0\widetilde{\chi}_3^0 decays can contribute significantly. (4)A double-wedge or wedge-protruding-from-a-box pattern on a wedgebox plot, which results from combining a variety of MSSM production processes, yields three distinct observed endpoints, almost always attributable to \widetilde{\chi}_{2,3,4}^0 \to \widetilde{\chi}_1^0 \ell^+\ell^- decays, which can be utilized to determine a great deal of information about the neutralino and slepton mass spectra and related MSSM input parameters. Wedge and double-wedge patterns are seen in wedgebox plots in another region of higher \mu and M_2 values, denoted as the`upper island.' Here the pattern is simpler and more stable as one moves across the (\mu, M_2) input parameter space.Comment: 28 pages (LaTeX), 8 figures (encapsulated postscript

Testing new-physics models with global comparisons to collider measurements: the Contur toolkit

Measurements at particle collider experiments, even if primarily aimed at understanding Standard Model processes, can have a high degree of model independence, and implicitly contain information about potential contributions from physics beyond the Standard Model. The Contur package allows users to benefit from the hundreds of measurements preserved in the Rivet library to test new models against the bank of LHC measurements to date. This method has proven to be very effective in several recent publications from the Contur team, but ultimately, for this approach to be successful, the authors believe that the Contur tool needs to be accessible to the wider high energy physics community. As such, this manual accompanies the first user-facing version: Contur v2. It describes the design choices that have been made, as well as detailing pitfalls and common issues to avoid. The authors hope that with the help of this documentation, external groups will be able to run their own Contur studies, for example when proposing a new model, or pitching a new search

Cellular and humoral immune responses and protection against schistosomes induced by a radiation-attenuated vaccine in chimpanzees

The radiation-attenuated Schistosoma mansoni vaccine is highly effective in rodents and primates but has never been tested in humans, primarily for safety reasons. To strengthen its status as a paradigm for a human recombinant antigen vaccine, we have undertaken a small-scale vaccination and challenge experiment in chimpanzees (Pan troglodytes). Immunological, clinical, and parasitological parameters were measured in three animals after multiple vaccinations, together with three controls, during the acute and chronic stages of challenge infection up to chemotherapeutic cure. Vaccination induced a strong in vitro proliferative response and early gamma interferon production, but type 2 cytokines were dominant by the time of challenge. The controls showed little response to challenge infection before the acute stage of the disease, initiated by egg deposition. In contrast, the responses of vaccinated animals were muted throughout the challenge period. Vaccination also induced parasite-specific immunoglobulin M (IgM) and IgG, which reached high levels at the time of challenge, while in control animals levels did not rise markedly before egg deposition. The protective effects of vaccination were manifested as an amelioration of acute disease and overall morbidity, revealed by differences in gamma-glutamyl transferase level, leukocytosis, eosinophilia, and hematocrit. Moreover, vaccinated chimpanzees had a 46% lower level of circulating cathodic antigen and a 38% reduction in fecal egg output, compared to controls, during the chronic phase of infection

The Underlying Event and the Total Cross Section from Tevatron to the LHC

Multiple partonic interactions are widely used to simulate the hadronic final state in high energy hadronic collisions, and successfully describe many features of the data. It is important to make maximum use of the available physical constraints on such models, particularly given the large extrapolation from current high energy data to LHC energies. In eikonal models, the rate of multiparton interactions is coupled to the energy dependence of the total cross section. Using a Monte Carlo implementation of such a model, we study the connection between the total cross section, the jet cross section, and the underlying event. By imposing internal consistency on the model, we derive constraints on its parameters at the LHC. By imposing internal consistency on the model and comparing to current data we constrain the allowed range of its parameters. We show that measurements of the total proton-proton cross-section at the LHC are likely to break this internal consistency, and thus to require an extension of the model. Likely such extensions are that hard scatters probe a denser matter distribution inside the proton in impact parameter space than soft scatters, a conclusion also supported by Tevatron data on double-parton scattering, and/or that the basic parameters of the model are energy dependent.Comment: 17 pages, 6 figures, version accepted by JHE

Carbonates Found in Stardust Aerogel Tracks

Preliminary examination of particles collected from Comet Wild 2 suggest that this comet is chondritic and formed under multiple processes. The lack of any hydrated minerals strongly suggests that most, if not all of these processes were anhydrous [1,2,3]. However, carbonates were found in particles extracted from 4 different tracks in the aerogel. It is our belief that these carbonates have a terrestrial origin and are a contaminant in these samples

Estimates of hadron azimuthal anisotropy from multiparton interactions in proton-proton collisions at sqrt(s) = 14 TeV

We estimate the amount of collective "elliptic flow" expected at mid-rapidity in proton-proton (p-p) collisions at the CERN Large Hadron Collider (LHC), assuming that any possible azimuthal anisotropy of the produced hadrons with respect to the plane of the reaction follows the same overlap-eccentricity and particle-density scalings as found in high-energy heavy ion collisions. Using a Glauber eikonal model, we compute the p-p eccentricities, transverse areas and particle-multiplicities for various phenomenological parametrisations of the proton spatial density. For realistic proton transverse profiles, we find integrated elliptic flow v2 parameters below 3% in p-p collisions at sqrt(s) = 14 TeV.Comment: 17 pages, 9 figures. Very minor mods. Version to appear in EPJ-