Event Reconstruction

The chapter gives an outline of the event reconstruction chain of a typical large experiment, from the trigger to the physics object reconstruction. The concept of the trigger is illustrated by two examples, CMS and LHCb, followed by a discussion of track reconstruction and its stages: hit generation, local reconstruction, and global reconstruction. The section on vertex reconstruction introduces a classification of vertices and sets the scene for the dedicated chapters on vertex finding and vertex fitting. The chapter concludes with some remarks on particle identification and reconstruction of physics objects such as electrons, muons, photons, jets,τleptons, and missing energy.

Global reconstruction of surface temperature fields for past equilibrium climates

<p>Paleoclimate simulations are widely used as a test of the ability of climate models to simulate climate states that are substantially different to the present day, and quantitative reconstructions of these climate states is an essential component of model evaluation.  With there being no large network of instrumental observations from these periods, we must rely on inferences from a relatively modest number of unevenly distributed proxy records which are believed to be quantitatively indicative of the climate state.  In order to robustly establish climatic conditions over global scales, we require methods for smoothing and interpolating between these sparse and imperfect estimates.  In recent years, we have worked on this problem and created a global reconstruction of the Last Glacial Maximum [Annan and Hargreaves, 2013, Climate of the Past] using the data and models which were available at that time.  The method uses scaled patterns from the PMIP ensemble of structurally diverse climate simulations, combined with sparse sets of proxy data, to produce spatially coherent and complete  data  fields  for  surface  air  and  sea  temperatures  (potentially  including  the  seasonal cycle)  along  with  uncertainty  estimates  over  the  whole  field.   This  approach  is  more  robust than alternative methods, which either perform a purely statistical interpolation of the data or at best combine the data with a single climate model. Here, we aim to improve the method, update the inputs, and apply the same technique to both Last Glacial Maximum and mid Pliocene climate intervals. As well as generating spatially complete and coherent maps of climate variables, our approach also generates well-calibrated uncertainty estimates.</p>

Reconstructions of Global and Regional Temperature Change for the Last 5 Myr

<p>We use a global array of ~120 sea-surface temperature (SST) records based on Mg/Ca, alkenone, and faunal proxies to reconstruct global and regional temperature change over the last 5 Myr. All records are placed on the LR04 age model. Here we report the reconstructions and discuss their implications for characterizing global climate evolution (frequency, variance, transitions) over this interval and its relationship to changes in CO2, orbital forcing, and mean ocean temperature. Average global temperature has cooled by ~6.5oC since 5 Ma, with significant breakpoints tentatively identified at ~3.38 Ma, 1.34 Ma, and 0.88 Ma. We also invert the global reconstruction to reconstruct global sea level for the last 5 Myr.</p>