118387873
Origin of the Cosmic Network: Nature vs Nurture
The large-scale structure of the Universe, as traced by the distribution of galaxies, is now being revealed by large-volume cosmological surveys. The structure is characterized by galaxies distributed along filaments, the filaments connecting in turn to form a percolating network. Our objective here is to quantitatively specify the underlying mechanisms that drive the formation of the cosmic network: By combining percolation-based analyses with N-body simulations of gravitational structure formation, we elucidate how the network has its origin in the properties of the initial density field (nature) and how its contrast is then amplified by the nonlinear mapping induced by the gravitational instability (nurture).
123165141
COMPUTATIONAL CHALLENGES IN HIGH INTENSITY ION BEAM PHYSICS
119221093
DARK MATTER HALO PROFILES OF MASSIVE CLUSTERS: THEORY VERSUS OBSERVATIONS
Dark-matter-dominated cluster-scale halos act as an important cosmological probe and provide a key testing ground for structure formation theory. Focusing on their mass profiles, we have carried out (gravity-only) simulations of the concordance ΛCDM cosmology, covering a mass range of 2 × 1012 to 2 × 1015 h –1 M ☉ and a redshift range of z = 0-2, while satisfying the associated requirements of resolution and statistical control. When fitting to the Navarro-Frenk-White profile, our concentration-mass (c-M) relation differs in normalization and shape in comparison to previous studies that have limited statistics in the upper end of the mass range. We show that the flattening of the c-M relation with redshift is naturally expressed if c is viewed as a function of the peak height parameter, ν. Unlike the c-M relation, the slope of the c-ν relation is effectively constant over the redshift range z = 0-2, while the amplitude varies by ~30% for massive clusters. This relation is, however, not universal: using a simulation suite covering the allowed wCDM parameter space, we show that the c-ν relation varies by about ±20% as cosmological parameters are varied. At fixed mass, the c(M) distribution is well fit by a Gaussian with σ c /c 1/3, independent of the radius at which the concentration is defined, the halo dynamical state, and the underlying cosmology. We compare the ΛCDM predictions with observations of halo concentrations from strong lensing, weak lensing, galaxy kinematics, and X-ray data, finding good agreement for massive clusters (M vir > 4 × 1014 h –1 M ☉), but with some disagreements at lower masses. Because of uncertainty in observational systematics and modeling of baryonic physics, the significance of these discrepancies remains unclear.
119451817
CHAOS IN TIME-DEPENDENT VARIATIONAL APPROXIMATIONS TO QUANTUM DYNAMICS
Dynamical chaos has recently been shown to exist in the Gaussian approximation in quan-tum mechanics and in the self-consistent mean ﬁeld approach to studying the dynamics ofquantum ﬁelds. In this study, we ﬁrst show that any variationalapproximationto the dynam-ics of a quantum system based on the Dirac action principle leads to a classical Hamiltoniandynamics for the variational parameters. Since this Hamiltonian is generically nonlinearand nonintegrable, the dynamics thus generated can be chaotic, in distinction to the exactquantum evolution. We then restrict attention to a system of two biquadratically coupledquantum oscillators and study two variational schemes, the leading order large N (fourcanonical variables) and Hartree (six canonical variables) approximations. The chaos seenin the approximate dynamics is an artifact of the approximations: this is demonstrated bythe fact that its onset occurs on the same characteristic time scale as the breakdown of theapproximations when compared to numerical solutions of the time-dependent Schr¨odingerequation.PACS numbers: 05.45. +b, 03.65. Sq, 2.30 Wd, 03.65 -w
1153539
Joint Efficient Dark-energy Investigation (JEDI): a Candidate Implementation of the NASA-DOE Joint Dark Energy Mission (JDEM)
JEDI will probe dark energy in three independent ways by measuring the expansion history of the universe: (1) using type Ia supernovae as cosmological standard candles over a range of distances, (2) using baryon oscillations as a cosmological standard ruler over a range of cosmic epochs, (3) mapping the weak gravitational lensing distortion by foreground galaxies of the images of background galaxies at different distances. JEDI will unravel the nature of dark energy with accuracy and precision. 
JEDI is a 2m-class space telescope with the unique ability of simultaneous wide-field imaging (0.8-4.2 micron in five bands) and multi-slit spectroscopy (0.8-3.2 micron) with a field of view of 1 square degree. What makes JEDI efficient is its ability to simultaneously obtain high signal-to-noise ratio, moderate resolution slit spectra for all supernovae and ~ 5000 galaxies in its wide field of view, and to combine imaging and spectroscopy so that the appropriate balance of time is devoted to each. 
JEDI will measure the cosmic expansion history H(z) as a free function to 10^9 galaxies to H \~ 25.
118744951
COSMIC EMULATION: THE CONCENTRATION-MASS RELATION FOR wCDM UNIVERSES
The concentration-mass relation for dark matter-dominated halos is one of the essential results expected from a theory of structure formation. We present a simple prediction scheme, a cosmic emulator, for the concentration-mass (c-M) relation as a function of cosmological parameters for wCDM models. The emulator is constructed from 37 individual models, with three nested N-body gravity-only simulations carried out for each model. The mass range covered by the emulator is 2 × 1012 M ☉ < M < 1015 M ☉ with a corresponding redshift range of z = 0-1. Over this range of mass and redshift, as well as the variation of cosmological parameters studied, the mean halo concentration varies from c ~ 2 to c ~ 8. The distribution of the concentration at fixed mass is Gaussian with a standard deviation of one-third of the mean value, almost independent of cosmology, mass, and redshift over the ranges probed by the simulations. We compare results from the emulator with previously derived heuristic analytic fits for the c-M relation, finding that they underestimate the halo concentration at high masses. Using the emulator to investigate the cosmology dependence of the c-M relation over the currently allowable range of values, we find—not surprisingly—that σ8 and ω m influence it considerably, but also that the dark energy equation-of-state parameter w has a substantial effect. In general, the concentration of lower-mass halos is more sensitive to changes in cosmological parameters as compared to cluster mass halos. The c-M emulator is publicly available from http://www.hep.anl.gov/cosmology/CosmicEmu.
119109223
Combined measurement and QCD analysis of the inclusive e±p scattering cross sections at HERA
A combination is presented of the inclusive deep inelastic cross sections measured by the H1 and ZEUS Collaborations in neutral and charged current unpolarised e±p scattering at HERA during the period 1994-2000. The data span six orders of magnitude in negative four-momentum-transfer squared, Q2, and in Bjorken x. The combination method used takes the correlations of systematic uncertainties into account, resulting in an improved accuracy. The combined data are the sole input in a NLO QCD analysis which determines a new set of parton distributions, HERAPDF1.0, with small experimental uncertainties. This set includes an estimate of the model and parametrisation uncertainties of the fit result.
117870820
Measurement of the diffractive longitudinal structure function $F_{L}^{D}$ at HERA
First measurements are presented of the diffractive cross section σep→eXY at centre-of-mass energies $\sqrt{s}$ of 225 and $252\mathrm {\;GeV}$, together with a precise new measurement at $\sqrt{s}$ of $319\mathrm {\;GeV}$, using data taken with the H1 detector in the years 2006 and 2007. Together with previous H1 data at $\sqrt{s}$ of $301\mathrm {\;GeV}$, the measurements are used to extract the diffractive longitudinal structure function $F_{L}^{D}$ in the range of photon virtualities $4.0 \leq Q^{2} \leq 44.0\mathrm {\;GeV}^{2}$ and fractional proton longitudinal momentum loss 5×10−4≤xℙ≤3×10−3. The measured $F_{L}^{D}$ is compared with leading twist predictions based on diffractive parton densities extracted in NLO QCD fits to previous measurements of diffractive Deep-Inelastic Scattering and with a model which additionally includes a higher twist contribution derived from a colour dipole approach. The ratio of the diffractive cross section induced by longitudinally polarised photons to that for transversely polarised photons is extracted and compared with the analogous quantity for inclusive Deep-Inelastic Scattering.
56222269
Low Mass WIMP Searches with a Neutrino Experiment: A Proposal for Further MiniBooNE Running
A proposal submitted to the FNAL PAC is described to search for light sub-GeV WIMP dark matter at MiniBooNE. The possibility to steer the beam past the target and into an absorber leads to a significant reduction in neutrino background, allowing for a sensitive search for elastic scattering of WIMPs off nucleons or electrons in the detector. Dark matter models involving a vector mediator can be probed in a parameter region consistent with the required thermal relic density, and which overlaps the region in which these models can resolve the muon g-2 discrepancy. Estimates of signal significance are presented for various operational modes and parameter points. The experimental approach outlined for applying MiniBooNE to a light WIMP search may also be applicable to other neutrino facilities.
16258094
Inclusive deep inelastic scattering at high Q2 with longitudinally polarised lepton beams at HERA
A BSTRACTInclusive e±p single and double differential cross sections for neutral and charged current deep inelastic scattering processes are measured with the H1 detector at HERA. The data were taken at a centre-of-mass energy of $ \sqrt {s} = {319} $ GeV with a total integrated luminosity of 333.7 pb−1 shared between two lepton beam charges and two longitudinal lepton polarisation modes. The differential cross sections are measured in the range of negative four-momentum transfer squared, Q2, between 60 and 50 000 GeV2, and Bjorken x between 0.0008 and 0.65. The measurements are combined with earlier published unpolarised H1 data to improve statistical precision and used to determine the structure function $ xF_{3}^{{\gamma Z}} $. Ameasurementoftheneutralcurrentparityviolating structure function $ F_{2}^{{\gamma Z}} $ is presented for the first time. The polarisation dependence of the charged current total cross section is also measured. The new measurements are well described by a next-to-leading order QCD fit based on all published H1 inclusive cross section data which are used to extract the parton distribution functions of the proton.
3141680
Direct measurement of backgrounds using reactor-off data in Double Chooz
Double Chooz is unique among modern reactor-based neutrino experiments studying $\bar \nu_e$ disappearance in that data can be collected with all reactors off. In this paper, we present data from 7.53 days of reactor-off running. Applying the same selection criteria as used in the Double Chooz reactor-on oscillation analysis, a measured background rate of 1.0$\pm$0.4 events/day is obtained. The background model for accidentals, cosmogenic $\beta$-$n$-emitting isotopes, fast neutrons from cosmic muons, and stopped-$\mu$ decays used in the oscillation analysis is demonstrated to be correct within the uncertainties. Kinematic distributions of the events, which are dominantly cosmic-ray-produced correlated-background events, are provided. The background rates are scaled to the shielding depths of two other reactor-based oscillation experiments, Daya Bay and RENO.