Author: Noemi CalacePublisher:
ISBN:
Category :
Languages : en
Pages : 238
Book Description
Jet Substructure Techniques for the Search of Diboson Resonances at the LHC and Performance Evaluation of the ATLAS Phase-II Inner Tracker Layouts
Author: Noemi CalaceLooking Inside Jets
Author: Simone MarzaniPublisher: Springer
ISBN: 3030157091
Category : Science
Languages : en
Pages : 205
Book Description
This concise primer reviews the latest developments in the field of jets. Jets are collinear sprays of hadrons produced in very high-energy collisions, e.g. at the LHC or at a future hadron collider. They are essential to and ubiquitous in experimental analyses, making their study crucial. At present LHC energies and beyond, massive particles around the electroweak scale are frequently produced with transverse momenta that are much larger than their mass, i.e., boosted. The decay products of such boosted massive objects tend to occupy only a relatively small and confined area of the detector and are observed as a single jet. Jets hence arise from many different sources and it is important to be able to distinguish the rare events with boosted resonances from the large backgrounds originating from Quantum Chromodynamics (QCD). This requires familiarity with the internal properties of jets, such as their different radiation patterns, a field broadly known as jet substructure. This set of notes begins by providing a phenomenological motivation, explaining why the study of jets and their substructure is of particular importance for the current and future program of the LHC, followed by a brief but insightful introduction to QCD and to hadron-collider phenomenology. The next section introduces jets as complex objects constructed from a sequential recombination algorithm. In this context some experimental aspects are also reviewed. Since jet substructure calculations are multi-scale problems that call for all-order treatments (resummations), the bases of such calculations are discussed for simple jet quantities. With these QCD and jet physics ingredients in hand, readers can then dig into jet substructure itself. Accordingly, these notes first highlight the main concepts behind substructure techniques and introduce a list of the main jet substructure tools that have been used over the past decade. Analytic calculations are then provided for several families of tools, the goal being to identify their key characteristics. In closing, the book provides an overview of LHC searches and measurements where jet substructure techniques are used, reviews the main take-home messages, and outlines future perspectives.
Advances in Jet Substructure at the LHC
Author: Roman KoglerPublisher: Springer Nature
ISBN: 3030728587
Category : Science
Languages : en
Pages : 287
Book Description
This book introduces the reader to the field of jet substructure, starting from the basic considerations for capturing decays of boosted particles in individual jets, to explaining state-of-the-art techniques. Jet substructure methods have become ubiquitous in data analyses at the LHC, with diverse applications stemming from the abundance of jets in proton-proton collisions, the presence of pileup and multiple interactions, and the need to reconstruct and identify decays of highly-Lorentz boosted particles. The last decade has seen a vast increase in our knowledge of all aspects of the field, with a proliferation of new jet substructure algorithms, calculations and measurements which are presented in this book. Recent developments and algorithms are described and put into the larger experimental context. Their usefulness and application are shown in many demonstrative examples and the phenomenological and experimental effects influencing their performance are discussed. A comprehensive overview is given of measurements and searches for new phenomena performed by the ATLAS and CMS Collaborations. This book shows the impressive versatility of jet substructure methods at the LHC.
Measuring Jet Substructure in Topologies Containing W, Top and Light Jets with the ATLAS Detector
Author: Amal VaidyaJet Substructure Without Trees
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 22
Book Description
We present an alternative approach to identifying and characterizing jet substructure. An angular correlation function is introduced that can be used to extract angular and mass scales within a jet without reference to a clustering algorithm. This procedure gives rise to a number of useful jet observables. As an application, we construct a top quark tagging algorithm that is competitive with existing methods. In preparation for the LHC, the past several years have seen extensive work on various aspects of collider searches. With the excellent resolution of the ATLAS and CMS detectors as a catalyst, one area that has undergone significant development is jet substructure physics. The use of jet substructure techniques, which probe the fine-grained details of how energy is distributed in jets, has two broad goals. First, measuring more than just the bulk properties of jets allows for additional probes of QCD. For example, jet substructure measurements can be compared against precision perturbative QCD calculations or used to tune Monte Carlo event generators. Second, jet substructure allows for additional handles in event discrimination. These handles could play an important role at the LHC in discriminating between signal and background events in a wide variety of particle searches. For example, Monte Carlo studies indicate that jet substructure techniques allow for efficient reconstruction of boosted heavy objects such as the W{sup {+-}} and Z° gauge bosons, the top quark, and the Higgs boson.
Jet Substructure for the LHC
Author: Martin David JankowiakPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
The discovery of new physics at the LHC hinges on our ability to discriminate the old (the Standard Model) from the new. The study of the substructure of jets offers a powerful set of techniques for improving the reach of new physics searches at the LHC. Moreover, jet substructure observables are a sensitive probe of QCD dynamics and motivate a variety of tests of QCD. This thesis explores several jet substructure techniques with a particular focus on applications to event discrimination. First, a jet observable is introduced that probes the color structure of pairs of subjets. This observable is incorporated into a top tagging algorithm, where it is shown to improve discrimination between top jets and QCD jets. Second, an alternative approach to jet substructure is introduced that is distinct from the prevailing methods based on the clustering trees induced by sequential jet algorithms. This approach makes use of two-particle angular correlations to identify substructure within jets. In one application, this approach is used to construct a top tagging algorithm that is competitive with existing methods. In another application, ensemble averages of angular correlations are used to study the underlying event and pile-up effects.
A Search for Massive Resonances Decaying to Top Quark Pairs and Jet Trigger Performance Studies with the ATLAS Detector at the Large Hadron Collider
Author: Luz Stella Gomez FajardoPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Alignment of the ATLAS Inner Detector in Run 2
Author: ATLAS Collaboration CERNPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Abstract: The performance of the ATLAS Inner Detector alignment has been studied using pp collision data at s√=13TeV collected by the ATLAS experiment during Run 2 (2015-2018) of the Large Hadron Collider (LHC). The goal of the detector alignment is to determine the detector geometry as accurately as possible and correct for time-dependent movements. The Inner Detector alignment is based on the minimization of track-hit residuals in a sequence of hierarchical levels, from global mechanical assembly structures to local sensors. Subsequent levels have increasing numbers of degrees of freedom; in total there are almost 750,000. The alignment determines detector geometry on both short and long timescales, where short timescales describe movements within an LHC fill. The performance and possible track parameter biases originating from systematic detector deformations are evaluated. Momentum biases are studied using resonances decaying to muons or to electrons. The residual sagitta bias and momentum scale bias after alignment are reduced to less than ∼0.1 TeV−1 and 0.9×10−3, respectively. Impact parameter biases are also evaluated using tracks within jets
Jet Dipolarity
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 7
Book Description
A new jet observable, dipolarity, is introduced that can distinguish whether a pair of subjets arises from a color singlet source. This observable is incorporated into the HEPTopTagger and is shown to improve discrimination between top jets and QCD jets for moderate to high p{sub T}. The impressive resolution of the ATLAS and CMS detectors means that a typical QCD jet at the LHC deposits energy in [Omicron](10-100) calorimeter cells. Such fine-grained calorimetry allows for jets to be studied in much greater detail than previously, with sophisticated versions of current techniques making it possible to measure more than just the bulk properties of jets (e.g. event jet multiplicities or jet masses). One goal of the LHC is to employ these techniques to extend the amount of information available from each jet, allowing for a broader probe of the properties of QCD. The past several years have seen significant progress in developing such jet substructure techniques. A number of general purpose tools have been developed, including: (i) top-tagging algorithms designed for use at both lower and higher p{sub T} as well as (ii) jet grooming techniques such as filtering, pruning, and trimming, which are designed to improve jet mass resolution. Jet substructure techniques have also been studied in the context of specific particle searches, where they have been shown to substantially extend the reach of traditional search techniques in a wide variety of scenarios, including for example boosted Higgses, neutral spin-one resonances, searches for supersymmetry, and many others. Despite these many successes, however, there is every reason to expect that there remains room for refinement of jet substructure techniques.
Author: Emanuele Usai