Rubin-LSST

Abstract:

Aims. A transient astrophysical event observed in both gravitational wave (GW) and electromagnetic (EM) channels would yield rich scientific rewards. A first program initiating EM follow-ups to possible transient GW events has been developed and exercised by the LIGO and Virgo community in association with several partners. In this paper, we describe and evaluate the methods used to promptly identify and localize GW event candidates and to request images of targeted sky locations. Methods. During two observing periods (Dec. 17, 2009 to Jan. 8, 2010 and Sep. 2 to Oct. 20, 2010), a low-latency analysis pipeline was used to identify GW event candidates and to reconstruct maps of possible sky locations. A catalog of nearby galaxies and Milky Way globular clusters was used to select the most promising sky positions to be imaged, and this directional information was delivered to EM observatories with time lags of about thirty minutes. A Monte Carlo simulation has been used to evaluate the low-latency GW pipeline's ability to reconstruct source positions correctly. Results. For signals near the detection threshold, our low-latency algorithms often localized simulated GW burst signals to tens of square degrees, while neutron star/neutron star inspirals and neutron star/black hole inspirals were localized to a few hundred square degrees. Localization precision improves for moderately stronger signals. The correct sky location of signals well above threshold and originating from nearby galaxies may be observed with ∼ 50% or better probability with a few pointings of wide-field telescopes. © 2012 ESO.

Abstract:

We have measured the W-boson mass MW using data corresponding to 2.2fb-1 of integrated luminosity collected in pp̄ collisions at √s=1.96TeV with the CDF II detector at the Fermilab Tevatron collider. Samples consisting of 470126 W→eν candidates and 624708 W→μν candidates yield the measurement MW=80387±12 stat.±15syst.=80387±19MeV/c2. This is the most precise measurement of the W-boson mass to date and significantly exceeds the precision of all previous measurements combined. © 2012 American Physical Society.

Abstract:

A search for a Higgs boson decaying into two photons is described. The analysis is performed using a dataset recorded by the CMS experiment at the LHC from pp collisions at a center-of-mass energy of 7 TeV, which corresponds to an integrated luminosity of 4.8 fb -1. Limits are set on the cross section of the standard model Higgs boson decaying to two photons. The expected exclusion limit at 95% confidence level is between 1.4 and 2.4 times the standard model cross section in the mass range between 110 and 150 GeV. The analysis of the data excludes, at 95% confidence level, the standard model Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The largest excess of events above the expected standard model background is observed for a Higgs boson mass hypothesis of 124 GeV with a local significance of 3.1σ. The global significance of observing an excess with a local significance ≥3.1σ anywhere in the search range 110-150 GeV is estimated to be 1.8σ. More data are required to ascertain the origin of this excess. © 2012 CERN.

Abstract:

The angular distributions of muons from Υ(1S,2S,3S) →μ+μ- decays are measured using data from pp̄ collisions at √s=1.96TeV corresponding to an integrated luminosity of 6.7fb-1 and collected with the CDF II detector at the Fermilab Tevatron. This analysis is the first to report the full angular distributions as functions of transverse momentum pT for Υ mesons in both the Collins-Soper and s-channel helicity frames. This is also the first measurement of the spin alignment of Υ(3S) mesons. Within the kinematic range of Υ rapidity |y|<0.6 and pT up to 40GeV/c, the angular distributions are found to be nearly isotropic. © 2012 American Physical Society.