117846935
Completing the sparticle spectrum at a multi-TeV linear collider?
If supersymmetry is realised in nature, the approved LHC and the planned sub-TeV linear collider should unravel some, maybe many, of the features of the sparticle world. We survey in this paper the task of comprehensively identifying, understanding and measuring all the particles predicted by the model. We start to address whether a multi-TeV linear collider such as CLIC whose energy may well exceed all the new particle production thresholds is suited to completing this challenging task.
118184457
Improving the Prompt Electromagnetic Energy Component of Jet Energy Resolution with pi0 Fitting in High Granularity Electromagnetic Calorimeters
We investigate improving the hadronic jet energy resolution using mass-constrained fits of pi0 decays using high granularity electromagnetic calorimeters. Single pi0 studies have indicated a large potential for improvement in the energy resolution of pi0's, typically reducing the average energy resolution by a factor of two for 4 GeV pi0's. We apply this method to fully simulated multi-hadronic events with multiple pi0's with widely varying energies using the ILD00 detector model. Several methods for identifying the correct pairings of photons with parent pi0's were explored. The combinatorics become challenging as the number of pi0's increases and we employ the Blossom V implementation of Edmonds' matching algorithm for handling this. For events where both photons of the pi0 are detected, the resulting solutions lead to an improvement in the pi0 component of the event energy resolution for 91.2 GeV Z0 events from 18.0%/sqrt(E) to 13.9%/sqrt(E) using the ILD00 detector and its reconstruction algorithms. This can be compared to a maximum potential improvement to 12.2%/sqrt(E) if all photon pairs are matched correctly using the current photon reconstruction.
121469905
D0 Results and Combined Tevatron Results on Standard Model Higgs
Abstract Results from the D0 experiment on the search for the Higgs boson of the Standard Model (SM) are presented with particular emphasis on testing the compatibility with recent LHC results on the observation of a Higgs-like particle. The D0 SM Higgs results, their combination and the Tevatron combination of CDF and D0 SM Higgs results are summarized. The article also puts recent developments in a historical context. The combined results from the Tevatron experiments give a local p-value of 0.4% for the background-only hypothesis at a mass of 125 GeV indicating that the combined Tevatron data strongly prefer the presence of a new particle with Standard Model Higgs-like properties in this mass region.
4504203
IRAS 15099–5856: REMARKABLE MID-INFRARED SOURCE WITH PROMINENT CRYSTALLINE SILICATE EMISSION EMBEDDED IN THE SUPERNOVA REMNANT MSH15–52
We report new mid-infrared (MIR) observations of the remarkable object IRAS 15099?5856 using the space telescopes AKARI and Spitzer, which demonstrate the presence of prominent crystalline silicate emission in this bright source. IRAS 15099?5856 has a complex morphology with a bright central compact source (IRS1) surrounded by knots, spurs, and several extended (~4') arc-like filaments. The source is seen only at ?10 ?m. The Spitzer mid-infrared spectrum of IRS1 shows prominent emission features from Mg-rich crystalline silicates, strong [Ne II] 12.81 ?m, and several other faint ionic lines. We model the MIR spectrum as thermal emission from dust and compare with the Herbig Be star HD?100546 and the luminous blue variable R71, which show very similar MIR spectra. Molecular line observations reveal two molecular clouds around the source, but no associated dense molecular cores. We suggest that IRS1 is heated by UV radiation from the adjacent O star Muzzio 10 and that its crystalline silicates most likely originated in a mass outflow from the progenitor of the supernova remnant (SNR) MSH 15?52. IRS1, which is embedded in the SNR, could have been shielded from the SN blast wave if the progenitor was in a close binary system with Muzzio 10. If MSH 15?52 is a remnant of Type Ib/c supernova (SN Ib/c), as has been previously proposed, this would confirm the binary model for SN Ib/c. IRS1 and the associated structures may be the relics of massive star death, as shaped by the supernova explosion, the pulsar wind, and the intense ionizing radiation of the embedded O star.
119361687
A Photometric and Weak Lensing Analysis of the z=0.42 Supercluster MS0302+17
We perform a weak lensing and photometric study of the z=0.42 supercluster MS0302+17 using deep I and V band images taken with the UH8K CCD mosaic camera at the CFHT. We use archival ROSAT HRI data to estimate fluxes, gas masses and, in one case, the binding mass of the three major clusters. We then use our CCD data to determine the optical richness and luminosities of the clusters and to map out the spatial distribution of the early type galaxies in the supercluster and in other foreground and background structures. We measure the gravitational shear from a sample of \simeq 30,000 faint background galaxies in the range 22<m_I<26 and find this correlates strongly with that predicted from the early type galaxies if they trace the mass with M/L_B \simeq 250 h. We make 2-dimensional reconstructions of the mass surface density. These recover all of the major concentrations of galaxies and indicate that most of the supercluster mass, like the early type galaxies, is concentrated in the three X-ray clusters, and we obtain mean mass-to-light ratios for the clusters of M/L_B \simeq 260 h. Cross-correlation of the measured mass surface density with that predicted from the early type galaxy distribution shows a strong peak at zero lag (significant at the \simeq 9-sigma level), and that at separations \gsim 200 h^{-1}$kpc the early galaxies trace the mass very accurately. This conclusion is supported by cross-correlation in Fourier space; we see little evidence for any variation of M/L or `bias' with scale, and from the longest wavelength modes with \lambda = 1.5-6 h^{-1}Mpc we find M/L \simeq (280 \pm 40)h, quite similar to that obtained for the cluster centers. We discuss the implication of these results for the cosmological density parameter.
6194823
New CMB Power Spectrum Constraints from MSAMI
We present new cosmic microwave background (CMB) anisotropy results from the combined analysis of the three flights of the first Medium Scale Anisotropy Measurement (MSAM1). This balloon-borne bolometric instrument measured about 10 square degrees of sky at half-degree resolution in 4 frequency bands from 5.2 cm to 20 cm with a high signal-to-noise ratio. Here we present an overview of our analysis methods, compare the results from the three flights, derive new constraints on the CMB power spectrum from the combined data and reduce the data to total power Wiener-filtered maps of the CMB. A key feature of this new analysis is a determination of the amplitude of CMB fluctuations at l ∼ 400. The analysis technique is described in a companion paper (Knox 1999). Subject headings: balloons — cosmic microwave background — cosmology: observations — infrared: ISM: continuum
396485
AzTEC millimetre survey of the COSMOS field – III. Source catalogue over 0.72 deg2 and plausible boosting by large-scale structure
We present a 0.72 deg^2 contiguous 1.1-mm survey in the central area of the Cosmological Evolution Survey field carried out to a 1σ ≈ 1.26 mJy beam^(−1) depth with the AzTEC camera mounted on the 10-m Atacama Submillimeter Telescope Experiment. We have uncovered 189 candidate sources at a signal-to-noise ratio (S/N) ≥ 3.5, out of which 129, with S/N ≥ 4, can be considered to have little chance of being spurious (≲ 2 per cent). We present the number counts derived with this survey, which show a significant excess of sources when compared to the number counts derived from the ~0.5 deg^2 area sampled at similar depths in the Submillimetre Common-User Bolometer Array (SCUBA) HAlf Degree Extragalactic Survey (SHADES). They are, however, consistent with those derived from fields that were considered too small to characterize the overall blank-field population. We identify differences to be more significant in the S_(1.1mm) ≳ 5 mJy regime, and demonstrate that these excesses in number counts are related to the areas where galaxies at redshifts z ≲ 1.1 are more densely clustered. The positions of optical–infrared galaxies in the redshift interval 0.6 ≲ z ≲ 0.75 are the ones that show the strongest correlation with the positions of the 1.1-mm bright population (S_(1.1mm) ≳ 5 mJy), a result which does not depend exclusively on the presence of rich clusters within the survey sampled area. The most likely explanation for the observed excess in number counts at 1.1-mm is galaxy–galaxy and galaxy–group lensing at moderate amplification levels, which increases in amplitude as one samples larger and larger flux densities. This effect should also be detectable in other high-redshift populations.
11394277
Obscured and unobscured active galactic nuclei in the Spitzer Space Telescope First Look Survey
Selection of active galactic nuclei (AGNs) in the infrared facilitates the discovery of AGNs whose optical emission is extinguished by dust. In this paper, we use the Spitzer Space Telescope First Look Survey (FLS) to assess the fraction of AGNs with mid-infrared (MIR) luminosities that are comparable to quasars and that are missed in optical quasar surveys because of dust obscuration. We begin by using the Sloan Digital Sky Survey (SDSS) database to identify 54 quasars within the 4 deg^2 extragalactic FLS. These quasars occupy a distinct region in MIR color space by virtue of their strong, red continua. This has allowed us to define an MIR color criterion for selecting AGN candidates. About 2000 FLS objects have colors that are consistent with them being AGNs, but most are much fainter in the MIR than the SDSS quasars, which typically have 8 μm flux densities S_(8.0) ~ 1 mJy. We have investigated the properties of 43 objects with S_(8.0) ≥ 1 mJy that satisfy our AGN color selection. This sample should contain both unobscured quasars as well as AGNs that are absent from the SDSS survey because of extinction in the optical. After removing 16 known quasars, three probable normal quasars, and eight spurious or confused objects from the initial sample of 43, we are left with 16 objects that are likely to be obscured quasars or luminous Seyfert 2 galaxies. This suggests that the numbers of obscured and unobscured AGNs are similar in samples selected in the MIR at S_(8.0) ~ 1 mJy.