122746402
Wigner Functions and Density Matrices in Curved Spaces as Computational Tools
Abstract This paper contrasts two alternative approaches to statistical quantum field theory in curved spacetimes, namely (1) a canonical Hamiltonian approach, in which the basic object is a density matrix ϱ characterizing the noncovariant, but globally defined, modes of the field; and (2) a Wigner function approach, in which the basic object is a Wigner function f defined quasilocally from the Hadamard, or correlation, function G 1 ( x 1 , x 2 ). The key object is to isolate on the conceptual biases underlying each of these approaches and then to assess their utility and limitations in effecting concrete calculations. The following questions are therefore addressed and largely answered. What sorts of spacetimes (e.g., de Sitter or Friedmann-Robertson-Walker) are comparatively easy to consider? What sorts of objects (e.g., average fields or renormalized stress energies) are easy to compute approximately? What, if anything, can be computed exactly? What approximations are intrinsic to each approach or convenient as computational tools? What sorts of “field entropies” are natural to define?
119181888
LSST Science Book, Version 2.0
A survey that can cover the sky in optical bands over wide fields to faint magnitudes with a fast cadence will enable many of the exciting science opportunities of the next decade. The Large Synoptic Survey Telescope (LSST) will have an effective aperture of 6.7 meters and an imaging camera with field of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over 20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a total point-source depth of r~27.5. The LSST Science Book describes the basic parameters of the LSST hardware, software, and observing plans. The book discusses educational and outreach opportunities, then goes on to describe a broad range of science that LSST will revolutionize: mapping the inner and outer Solar System, stellar populations in the Milky Way and nearby galaxies, the structure of the Milky Way disk and halo and other objects in the Local Volume, transient and variable objects both at low and high redshift, and the properties of normal and active galaxies at low and high redshift. It then turns to far-field cosmological topics, exploring properties of supernovae to z~1, strong and weak lensing, the large-scale distribution of galaxies and baryon oscillations, and how these different probes may be combined to constrain cosmological models and the physics of dark energy.
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.
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
123165141
COMPUTATIONAL CHALLENGES IN HIGH INTENSITY ION BEAM PHYSICS
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.
119246325
Measurement of photon production in the very forward direction in deep-inelastic scattering at HERA
The production of photons at very small angles with respect to the proton beam direction is studied in deep-inelastic positron–proton scattering at HERA. The data are taken with the H1 detector in the years 2006 and 2007 and correspond to an integrated luminosity of 126 pb−1. The analysis covers the range of negative four momentum transfer squared at the positron vertex 6<Q2<100 GeV2 and inelasticity 0.05<y<0.6. Cross sections are measured for the most energetic photon with pseudorapidity η>7.9as a function of its transverse momentum $p_{T}^{\mathrm{lead}}$ and longitudinal momentum fraction of the incoming proton $x_{L}^{\mathrm{lead}}$. In addition, the cross sections are studied as a function of the sum of the longitudinal momentum fraction $x_{L}^{\mathrm{sum}}$ of all photons in the pseudorapidity range η>7.9. The cross sections are normalised to the inclusive deep-inelastic scattering cross section and compared to the predictions of models of deep-inelastic scattering and models of the hadronic interactions of high energy cosmic rays.
7328744
Search for lepton flavour violation in ep collisions at HERA
A search for the lepton flavour violating processes ep→μX and ep→τX is performed with the H1 experiment at HERA. Final states with a muon or tau and a hadronic jet are searched for in a data sample corresponding to an integrated luminosity of 66.5 pb-1 for e+p collisions and 13.7 pb-1 for e-p collisions at a centre-of-mass energy of 319 GeV. No evidence for lepton flavour violation is found. Limits are derived on the mass and the couplings of leptoquarks inducing lepton flavour violation in an extension of the Buchmüller–Rückl–Wyler effective model. Leptoquarks produced in ep collisions with a coupling strength of λ=0.3 and decaying with the same coupling strength to a muon–quark pair or a tau–quark pair are excluded at 95% confidence level up to masses of 459 GeV and 379 GeV, respectively.
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.
15282179
Measurement of inclusive and dijet D∗ meson cross sections in photoproduction at HERA
The inclusive photoproduction of D∗ mesons and of D∗-tagged dijets is investigated with the H1 detector at the ep collider HERA. The kinematic region covers small photon virtualities Q2<2 GeV2 and photon–proton centre-of-mass energies of 100<Wγp<285 GeV. Inclusive D∗ meson differential cross sections are measured for central rapidities |η(D∗)|<1.5 and transverse momenta pT(D∗)>1.8 GeV. The heavy quark production process is further investigated in events with at least two jets with transverse momentum pT(jet)>3.5 GeV each, one containing the D∗ meson. Differential cross sections for D∗-tagged dijet production and for correlations between the jets are measured in the range |η(D∗)|<1.5 and pT(D∗)>2.1 GeV. The results are compared with predictions from Monte Carlo simulations and next-to-leading order perturbative QCD calculations.
14167506
Study of charm fragmentation into D* ± mesons in deep-inelastic scattering at HERA
The process of charm quark fragmentation is studied using D* ± meson production in deep-inelastic scattering as measured by the H1 detector at HERA. The parameters of fragmentation functions are extracted for QCD models based on leading order matrix elements and DGLAP or CCFM evolution of partons together with string fragmentation and particle decays. Additionally, they are determined for a next-to-leading order QCD calculation in the fixed flavour number scheme using the independent fragmentation of charm quarks to D* ± mesons. Two different regions of phase space are investigated defined by the presence or absence of a jet containing the D* ± meson in the event. The fragmentation parameters extracted for the two phase space regions are found to be different.