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.
120927860
Thin, high gain wire chambers for electromagnetic presampling in OPAL
Abstract Thin multiwire chambers, operating in a high gain mode, are used for electromagnetic presampling in the endcaps of the OPAL detector at LEP. The design, setup and performance of these chambers with respect to energy and space resolution for electromagnetic showers as well as to pion/electron separation is described.
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.
14088596
THE AzTEC/SMA INTERFEROMETRIC IMAGING SURVEY OF SUBMILLIMETER-SELECTED HIGH-REDSHIFT GALAXIES
We present results from a continuing interferometric survey of high-redshift submillimeter galaxies (SMGs) with the Submillimeter Array, including high-resolution (beam size approx2 arcsec) imaging of eight additional AzTEC 1.1 mm selected sources in the COSMOS field, for which we obtain six reliable (peak signal-to-noise ratio (S/N) >5 or peak S/N >4 with multiwavelength counterparts within the beam) and two moderate significance (peak S/N >4) detections. When combined with previous detections, this yields an unbiased sample of millimeter-selected SMGs with complete interferometric follow up. With this sample in hand, we (1) empirically confirm the radio-submillimeter association, (2) examine the submillimeter morphology-including the nature of SMGs with multiple radio counterparts and constraints on the physical scale of the far infrared-of the sample, and (3) find additional evidence for a population of extremely luminous, radio-dim SMGs that peaks at higher redshift than previous, radio-selected samples. In particular, the presence of such a population of high-redshift sources has important consequences for models of galaxy formation-which struggle to account for such objects even under liberal assumptions-and dust production models given the limited time since the big bang.
55835836
FILAMENTARY ACCRETION FLOWS IN THE EMBEDDED SERPENS SOUTH PROTOCLUSTER
One puzzle in understanding how stars form in clusters is the source of mass—is all of the mass in place before the first stars are born, or is there an extended period when the cluster accretes material which can continuously fuel the star formation process? We use a multi-line spectral survey of the southern filament associated with the Serpens South embedded cluster-forming region in order to determine if mass is accreting from the filament onto the cluster, and whether the accretion rate is significant. Our analysis suggests that material is flowing along the filament's long axis at a rate of ~30 M ☉ Myr–1 (inferred from the N2H+ velocity gradient along the filament), and radially contracting onto the filament at ~130 M ☉ Myr–1 (inferred from HNC self-absorption). These accretion rates are sufficient to supply mass to the central cluster at a similar rate to the current star formation rate in the cluster. Filamentary accretion flows may therefore be very important in the ongoing evolution of this cluster.
2476452
Atmospheric consequences of cosmic ray variability in the extragalactic shock model: 2. Revised ionization levels and their consequences
This is the publisher's version, also available electronically from http://onlinelibrary.wiley.com.
16415445
Spitzer Observations of z ~ 3 Lyman Break Galaxies: Stellar Masses and Mid-Infrared Properties
We describe the spectral energy distributions (SEDs) of Lyman break galaxies (LBGs) at z ~ 3, using deep mid-infrared and optical observations of the extended Groth strip, obtained with IRAC and MIPS on board Spitzer and from the ground, respectively. We focus on LBGs with detections at all four IRAC bands, in particular the 26 galaxies with IRAC 8 μm band (rest-frame K-band) detections. We use stellar population-synthesis models and probe the stellar content of these galaxies. Based on best-fit continuous star formation models, we derive estimates of the stellar mass for these LBGs. As in previous studies, we find that a fraction of LBGs have very red colors and large estimated stellar masses (M_* > 5 × 10^(10) M_⊙); the current Spitzer data allow us, for the first time, to study these massive LBGs in detail. We discuss the link between these LBGs and submillimeter-luminous galaxies, and we find that the number density of these massive LBGs at high redshift is higher than predicted by current semianalytic models of galaxy evolution.
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