# United States Department of Energy High Energy Physics Division

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Works: 2,929 works in 2,977 publications in 1 language and 9,085 library holdings Conference papers and proceedings Sponsor, Researcher, Other
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High energy density and high power RF : 5th Workshop on High Energy Density and High Power RF : Snowbird, Utah, 1-5 October 2001 by Workshop on High Energy Density and High Power RF( Book )

2 editions published in 2002 in English and held by 146 WorldCat member libraries worldwide

Search for Diphoton Resonances in the Mass Range from 150 to 850 GeV in pp Collisions at $\sqrt{s}$ = 8 TeV( )

10 editions published in 2015 in English and held by 30 WorldCat member libraries worldwide

Two searches for physics beyond the standard model in events containing photons are presented. Our data sample used corresponds to an integrated luminosity of 19.7 fb-1 of proton-proton collisions at √s=8 TeV, collected with the CMS experiment at the CERN LHC. The analyses pursue different inclusive search strategies. One analysis requires at least one photon, at least two jets, and a large amount of transverse momentum imbalance, while the other selects events with at least two photons and at least one jet, and uses the razor variables to search for signal events. The background expected from standard model processes is evaluated mainly from data. These results are interpreted in the context of general gauge-mediated supersymmetry, with the next-to-lightest supersymmetric particle either a bino- or wino-like neutralino, and within simplified model scenarios. Upper limits at the 95% confidence level are obtained for cross sections as functions of the masses of the intermediate supersymmetric particles
Searches for third-generation squark production in fully hadronic final states in proton-proton collisions at [arrow]" = 8 TeV( )

4 editions published in 2015 in English and held by 12 WorldCat member libraries worldwide

The purely electroweak (EW) cross section for the production of two jets in association with a Z boson, in proton-proton collisions at [arrow]" = 8 TeV, is measured using data recorded by the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of 19.7 fb-1. The electroweak cross section for the lljj final state (with l = e or [mu] and j representing the quarks produced in the hard interaction) in the kinematic region defined by Mll> 50 GeV, Mjj> 120 GeV, transverse momentum pTj> 25 GeV, and pseudorapidity
Search for Resonant $\mathrm{t\bar{t}}$ Production in Proton-Proton Collisions at $\sqrt{s}$ = 8 TeV( )

3 editions published in 2015 in English and held by 9 WorldCat member libraries worldwide

A description is provided of the performance of the CMS detector for photon reconstruction and identification in proton-proton collisions at a centre-of-mass energy of 8 TeV at the CERN LHC. Details are given on the reconstruction of photons from energy deposits in the electromagnetic calorimeter (ECAL) and the extraction of photon energy estimates. Furthermore, the reconstruction of electron tracks from photons that convert to electrons in the CMS tracker is also described, as is the optimization of the photon energy reconstruction and its accurate modelling in simulation, in the analysis of the Higgs boson decay into two photons. In the barrel section of the ECAL, an energy resolution of about 1% is achieved for unconverted or late-converting photons from H → [gamma][gamma] decays. Furthermore, different photon identification methods are discussed and their corresponding selection efficiencies in data are compared with those found in simulated events
Search for W' decaying to tau lepton and neutrino in proton-proton collisions at $\sqrt{s}$ = 8 TeV( )

2 editions published in 2015 in English and held by 6 WorldCat member libraries worldwide

Results are reported of a general search for pair production of heavy resonances decaying to pairs of jets in events with at least four jets. The study is based on up to 19.4 inverse femtobarns of integrated luminosity from proton-proton collisions at a center-of-mass energy of 8 TeV, recorded with the CMS detector at the LHC. Limits are determined on the production of scalar top quarks (top squarks) in the framework of R-parity violating supersymmetry and on the production of color-octet vector bosons (colorons). First limits at the LHC are placed on top squark production for two scenarios. The first assumes decay to a bottom quark and a light-flavor quark and is excluded for masses between 200 and 385 GeV, and the second assumes decay to a pair of light-flavor quarks and is excluded for masses between 200 and 350 GeV at 95% confidence level. Previous limits on colorons decaying to light-flavor quarks are extended to exclude masses from 200 to 835 GeV
An ultra-weak sector, the strong CP problem and the pseudo-Goldstone dilaton( )

2 editions published between 2014 and 2015 in English and held by 6 WorldCat member libraries worldwide

In the context of a Coleman-Weinberg mechanism for the Higgs boson mass, we address the strong CP problem. We show that a DFSZ-like invisible axion model with a gauge-singlet complex scalar field S, whose couplings to the Standard Model are naturally ultra-weak, can solve the strong CP problem and simultaneously generate acceptable electroweak symmetry breaking. The ultra-weak couplings of the singlet S are associated with underlying approximate shift symmetries that act as custodial symmetries and maintain technical naturalness. The model also contains a very light pseudo-Goldstone dilaton that is consistent with cosmological Polonyi bounds, and the axion can be the dark matter of the universe. We further outline how a SUSY version of this model, which may be required in the context of Grand Unification, can avoid introducing a hierarchy problem
First measurement of neutrino and antineutrino coherent charged pion production on argon( )

2 editions published between 2014 and 2015 in English and held by 6 WorldCat member libraries worldwide

We report on the first cross section measurements for charged current coherent pion production by neutrinos and antineutrinos on argon. These measurements are performed using the ArgoNeuT detector exposed to the NuMI beam at Fermilab. The cross sections are measured to be 2.6 +1.2-1.0 (stat)+0.3-0.4(syst) × 10⁻³⁸cm² / Ar for neutrinos at a mean energy of 9.6 GeV and 5.5+2.6-2.1(stat)+0.6-0.7(syst) × 10⁻³⁹ cm² / Ar for antineutrinos at a mean energy of 3.6 GeV
Effect of event selection on jetlike correlation measurement in [mml : math altimg="si1.gif" overflow="scroll" xmlns xocs="http //www.elsevier.com/xml/xocs/dtd" xmlns xs="http //www.w3.org/2001/XMLSchema" xmlns xsi="http //www.w3.org/2001/XMLSchema-instance" xmlns="http //www.elsevier.com/xml/ja/dtd" xmlns ja="http //www.elsevier.com/xml/ja/dtd" xmlns mml="http //www.w3.org/1998/Math/MathML" xmlns tb="http //www.elsevier.com/xml/common/table/dtd" xmlns sb="http //www.elsevier.com/xml/common/struct-bib/dtd" xmlns ce="http //www.elsevier.com/xml/common/dtd" xmlns xlink="http //www.w3.org/1999/xlink" xmlns cals="http //www.elsevier.com/xml/common/cals/dtd" xmlns sa="http //www.elsevier.com/xml/common/struct-aff/dtd"][mml mi]d[/mml mi][mml mo]+[/mml mo][mml mrow][mml mi mathvariant="normal"]Au[/mml mi][/mml mrow][/mml math] collisions at [mml math altimg="si2.gif" overflow="scroll" xmlns xocs="http //www.elsevier.com/xml/xocs/dtd" xmlns xs="http //www.w3.org/2001/XMLSchema" xmlns xsi="http //www.w3.org/2001/XMLSchema-instance" xmlns="http //www.elsevier.com/xml/ja/dtd" xmlns ja="http //www.elsevier.com/xml/ja/dtd" xmlns mml="http //www.w3.org/1998/Math/MathML" xmlns tb="http //www.elsevier.com/xml/common/table/dtd" xmlns sb="http //www.elsevier.com/xml/common/struct-bib/dtd" xmlns ce="http //www.elsevier.com/xml/common/dtd" xmlns xlink="http //www.w3.org/1999/xlink" xmlns cals="http //www.elsevier.com/xml/common/cals/dtd" xmlns sa="http //www.elsevier.com/xml/common/struct-aff/dtd"][mml msqrt][mml msub][mml mrow][mml mi][/mml mi][/mml mrow][mml mrow][mml mi mathvariant="normal"]NN[/mml mi][/mml mrow][/mml msub][/mml msqrt][mml mo]=[/mml mo][mml mn]200[/mml mn][mml mtext] [/mml mtext][mml mtext]GeV[/mml mtext][/mml math]( )

2 editions published in 2015 in English and held by 6 WorldCat member libraries worldwide

In this study, dihadron correlations are analyzed in √sNN = 200 GeV d+Au collisions classified by forward charged particle multiplicity and zero-degree neutral energy in the Au-beam direction. It is found that the jetlike correlated yield increases with the event multiplicity. After taking into account this dependence, the non-jet contribution on the away side is minimal, leaving little room for a back-to-back ridge in these collisions
The LMC geometry and outer stellar populations from early DES data( )

2 editions published in 2015 in English and held by 6 WorldCat member libraries worldwide

Performance and results of the LBNE 35 ton membrane cryostat prototype( )

2 editions published in 2015 in English and held by 6 WorldCat member libraries worldwide

We report on the performance and commissioning of the first membrane cryostat to be used for scientific application. The Long Baseline Neutrino Experiment (LBNE) has designed and fabricated a membrane cryostat prototype in collaboration with Ishikawajima-Harima Heavy Industries Co., Ltd. (IHI). LBNE has designed and fabricated the supporting cryogenic system infrastructure and successfully commissioned and operated the first membrane cryostat. Original goals of the prototype are: to demonstrate the membrane cryostat technology in terms of thermal performance, feasibility for liquid argon and leak tightness; to demonstrate that we can remove all the impurities from the vessel and achieve the purity requirements in a membrane cryostat without evacuation; to demonstrate that we can achieve and maintain the purity requirements of the liquid argon using mol sieve and copper filters. The purity requirements of a large liquid argon detector such as LBNE are contaminants below 200 parts per trillion (ppt) oxygen equivalent. LBNE is planning the design and construction of a large liquid argon detector. This presentation will present requirements, design and construction of the LBNE 35 ton membrane cryostat prototype, and detail the commissioning and performance. The experience and results of this prototype are extremely important for the development of the LBNE detector
Cosmological implications of baryon acoustic oscillation measurements( )

2 editions published in 2015 in English and held by 6 WorldCat member libraries worldwide

Here, we derive constraints on cosmological parameters and tests of dark energy models from the combination of baryon acoustic oscillation (BAO) measurements with cosmic microwave background (CMB) data and a recent reanalysis of Type Ia supernova (SN) data. In particular, we take advantage of high-precision BAO measurements from galaxy clustering and the Lyman-[alpha] forest (LyaF) in the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). Treating the BAO scale as an uncalibrated standard ruler, BAO data alone yield a high confidence detection of dark energy; in combination with the CMB angular acoustic scale they further imply a nearly flat universe. Adding the CMB-calibrated physical scale of the sound horizon, the combination of BAO and SN data into an "inverse distance ladder" yields a measurement of H0=67.3±1.1 km s1 Mpc₋1, with 1.7% precision. This measurement assumes standard prerecombination physics but is insensitive to assumptions about dark energy or space curvature, so agreement with CMB-based estimates that assume a flat [Lambda]CDM cosmology is an important corroboration of this minimal cosmological model. For constant dark energy ([Lambda]), our BAO+SN+CMB combination yields matter density [Omega]m=0.301±0.008 and curvature [Omega]k=₋0.003±0.003. When we allow more general forms of evolving dark energy, the BAO+SN+CMB parameter constraints are always consistent with flat [Lambda]CDM values at H"[sigma]. While the overall [chi]2 of model fits is satisfactory, the LyaF BAO measurements are in moderate (2-2.5[sigma]) tension with model predictions. Models with early dark energy that tracks the dominant energy component at high redshift remain consistent with our expansion history constraints, and they yield a higher H0 and lower matter clustering amplitude, improving agreement with some low redshift observations. Expansion history alone yields an upper limit on the summed mass of neutrino species, [Sigma]m[nu]<0.56 eV (95% confidence), improving to [Sigma]m[nu]<0.25 eV if we include the lensing signal in the Planck CMB power spectrum. In a flat [Lambda]CDM model that allows extra relativistic species, our data combination yields Neff=3.43±0.26; while the LyaF BAO data prefer higher Neff when excluding galaxy BAO, the galaxy BAO alone favor Neff H"3. Lastly, when structure growth is extrapolated forward from the CMB to low redshift, standard dark energy models constrained by our data predict a level of matter clustering that is high compared to most, but not all, observational estimates
Measurements of the Upsilon(1S), Upsilon(2S), and Upsilon(3S) differential cross sections in pp collisions at sqrt(s) = 7 TeV( )

2 editions published in 2015 in English and held by 6 WorldCat member libraries worldwide

Measurements of diffractive dissociation cross sections in pp collisions at [arrow]"=7 TeV are presented in kinematic regions defined by the masses MX and MY of the two final-state hadronic systems separated by the largest rapidity gap in the event. The differential cross sections are measured as a function of [xi]X = M2X /s in the region -5.5 <log10[xi]X <-2.5, for log10MY <0.5, dominated by single dissociation (SD), and 0.5 <log10MY <1.1, dominated by double dissociation (DD), where MX and MY are given in GeV. The inclusive pp cross section is also measured as a function of the width of the central pseudorapidity gap [Delta][eta] for [Delta][eta]> 3, log10 MX> 1.1, and log10MY> 1.1, a region dominated by DD. The cross sections integrated over these regions are found to be, respectively, 2.99 " 0.02(stat)+0.32-0.29(syst) mb, 1.18 " 0.02(stat) " 0.13(syst) mb, and 0.58 " 0.01(stat)+0.13-0.11(syst) mb, and are used to extract extrapolated total SD and DD cross sections. In addition, the inclusive differential cross section, d[sigma]/d[Delta][eta]F, for events with a pseudorapidity gap adjacent to the edge of the detector, is measured over [Delta][eta]F = 8.4 units of pseudorapidity. The results are compared to those of other experiments and to theoretical predictions and found compatible with slowly rising diffractive cross sections as a function of center-of-mass energy
Automated Transient Identification in the Dark Energy Survey( )

2 editions published in 2015 in English and held by 6 WorldCat member libraries worldwide

We describe an algorithm for identifying point-source transients and moving objects on reference-subtracted optical images containing artifacts of processing and instrumentation. The algorithm makes use of the supervised machine learning technique known as Random Forest. We present results from its use in the Dark Energy Survey Supernova program (DES-SN), where it was trained using a sample of 898,963 signal and background events generated by the transient detection pipeline. After reprocessing the data collected during the first DES-SN observing season (2013 September through 2014 February) using the algorithm, the number of transient candidates eligible for human scanning decreased by a factor of 13.4, while only 1.0 percent of the artificial Type Ia supernovae (SNe) injected into search images to monitor survey efficiency were lost, most of which were very faint events. Here we characterize the algorithm's performance in detail, and we discuss how it can inform pipeline design decisions for future time-domain imaging surveys, such as the Large Synoptic Survey Telescope and the Zwicky Transient Facility
MINERvA neutrino detector response measured with test beam data( )

2 editions published in 2015 in English and held by 6 WorldCat member libraries worldwide

The MINERvA collaboration operated a scaled-down replica of thesolid scintillator tracking and sampling calorimeter regions of the MINERvA detector in a hadron test beam at the Fermilab Test Beam Facility. This paper reports measurements with samples of protons, pions, and electrons from 0.35 to 2.0 GeV/c momentum. The calorimetric response to protons, pions, and electrons is obtained from these data. A measurement of the parameter in Birks' law and an estimate of the tracking efficiency are extracted from the proton sample. Overall the data are well described by a Geant4-based Monte Carlo simulation of the detector and particle interactions with agreements better than 4% for the calorimetric response, though some features of the data are not precisely modeled. These measurements are used to tune the MINERvA detector simulation and evaluate systematic uncertainties in support of the MINERvA neutrino cross-section measurement program
Final Report( )

2 editions published between 2012 and 2013 in English and held by 6 WorldCat member libraries worldwide

Supernova explosions are the central events in astrophysics. They are the major agencies of change in the interstellar medium, driving star formation and the evolution of galaxies. Their gas remnants are the birthplaces of the cosmic rays. Such is their brightness that they can be used as standard candles to measure the size and geometry of the universe and their investigation draws on particle and nuclear physics, radiative transfer, kinetic theory, gravitational physics, thermodynamics, and the numerical arts. Hence, supernovae are unrivaled astrophysical laboratories. We will develop new state-of-the-art multi-dimensional radiation hydrodynamic codes to address this and other related astrophysical phenomena
Isolation of flow and nonflow correlations by two- and four-particle cumulant measurements of azimuthal harmonics in [arrow]"NN = 200 GeV Au+Au collisions( )

2 editions published in 2015 in English and held by 6 WorldCat member libraries worldwide

A data-driven method was applied to Au+Au collisions at [arrow]"NN = 200 GeV made with the STAR detector at RHIC to isolate pseudorapidity distance [Delta][eta]-dependent and [Delta][eta]-independent correlations by using two- and four-particle azimuthal cumulant measurements. We identified a [Delta][eta]-independent component of the correlation, which is dominated by anisotropic flow and flow fluctuations. It was also found to be independent of [eta] within the measured range of pseudorapidity
DES13S2cmm : the first superluminous supernova from the Dark Energy Survey( )

2 editions published in 2015 in English and held by 6 WorldCat member libraries worldwide

Simulation of transverse modes with their intrinsic Landau damping for bunched beams in the presence of space charge( )

2 editions published in 2015 in English and held by 6 WorldCat member libraries worldwide

Summary of the Second Workshop on Liquid Argon Time Projection Chamber Research and Development in the United States( )

2 editions published in 2015 in English and held by 6 WorldCat member libraries worldwide

The second workshop to discuss the development of liquid argon time projection chambers (LArTPCs) in the United States was held at Fermilab on July 8-9, 2014. The workshop was organized under the auspices of the Coordinating Panel for Advanced Detectors, a body that was initiated by the American Physical Society Division of Particles and Fields. All presentations at the workshop were made in six topical plenary sessions: i) Argon Purity and Cryogenics, ii) TPC and High Voltage, iii) Electronics, Data Acquisition and Triggering, iv) Scintillation Light Detection, v) Calibration and Test Beams, and vi) Software. This document summarizes the current efforts in each of these areas. It primarily focuses on the work in the US, but also highlights work done elsewhere in the world
Measurement of the ratio of the production cross sections times branching fractions of Bc" ₂!J/[psi][pi]"and B" ₂!J/[psi] K" and B(Bc"₂!J/[psi] [pi]"[pi]"[pi]-/+)/B(Bc" ₂!J/[psi] [pi]") in pp collisions at [arrow]" = 7 TeV( )

2 editions published between 2014 and 2015 in English and held by 6 WorldCat member libraries worldwide

The ratio of the production cross sections times branching fractions ([sigma](Bc") B(Bc" ₂!J/[psi][pi]"))/([sigma](B") B(B" ₂!J/[psi]K") is studied in proton-proton collisions at a center-of-mass energy of 7 TeV with the CMS detector at the LHC. The kinematic region investigated requires Ba, sub>c" and B"mesons with transverse momentum p[tau]> 15 GeV and rapidity

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United States. Department of Energy. Office of Science. High Energy Physics Division

United States. Dept. of Energy. High Energy Physics Division

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English (51)