Performance of Photon Reconstruction and Identification with the CMS Detector in Proton-proton Collisions at {u221A}s PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Performance of Photon Reconstruction and Identification with the CMS Detector in Proton-proton Collisions at {u221A}s PDF full book. Access full book title Performance of Photon Reconstruction and Identification with the CMS Detector in Proton-proton Collisions at {u221A}s by . Download full books in PDF and EPUB format.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 59
Get Book Here
Book Description
A description is provided of the performance of the CMS detector for photon reconstruction and identification in proton-proton collisions at a centre-of-mass energy of 8 TeV at the CERN LHC. Details are given on the reconstruction of photons from energy deposits in the electromagnetic calorimeter (ECAL) and the extraction of photon energy estimates. Furthermore, the reconstruction of electron tracks from photons that convert to electrons in the CMS tracker is also described, as is the optimization of the photon energy reconstruction and its accurate modelling in simulation, in the analysis of the Higgs boson decay into two photons. In the barrel section of the ECAL, an energy resolution of about 1% is achieved for unconverted or late-converting photons from H → ?? decays. Furthermore, different photon identification methods are discussed and their corresponding selection efficiencies in data are compared with those found in simulated events.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 59
Get Book Here
Book Description
A description is provided of the performance of the CMS detector for photon reconstruction and identification in proton-proton collisions at a centre-of-mass energy of 8 TeV at the CERN LHC. Details are given on the reconstruction of photons from energy deposits in the electromagnetic calorimeter (ECAL) and the extraction of photon energy estimates. Furthermore, the reconstruction of electron tracks from photons that convert to electrons in the CMS tracker is also described, as is the optimization of the photon energy reconstruction and its accurate modelling in simulation, in the analysis of the Higgs boson decay into two photons. In the barrel section of the ECAL, an energy resolution of about 1% is achieved for unconverted or late-converting photons from H → ?? decays. Furthermore, different photon identification methods are discussed and their corresponding selection efficiencies in data are compared with those found in simulated events.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 59
Get Book Here
Book Description
A description is provided of the performance of the CMS detector for photon reconstruction and identification in proton-proton collisions at a centre-of-mass energy of 8 TeV at the CERN LHC. Details are given on the reconstruction of photons from energy deposits in the electromagnetic calorimeter (ECAL) and the extraction of photon energy estimates. Furthermore, the reconstruction of electron tracks from photons that convert to electrons in the CMS tracker is also described, as is the optimization of the photon energy reconstruction and its accurate modelling in simulation, in the analysis of the Higgs boson decay into two photons. In the barrel section of the ECAL, an energy resolution of about 1% is achieved for unconverted or late-converting photons from H → [gamma][gamma] decays. Furthermore, different photon identification methods are discussed and their corresponding selection efficiencies in data are compared with those found in simulated events.
Author: Kevin Patrick McDermott
Publisher:
ISBN:
Category :
Languages : en
Pages : 206
Get Book Here
Book Description
This dissertation presents a search for long-lived particles using delayed photons in proton-proton collisions at sqrt(s) = 13 TeV recorded by the Compact Muon Solenoid (CMS) experiment at the CERN Large Hadron Collider in 2017, corresponding to an integrated luminosity of 41.5 fb^-1. This analysis includes a number of unique components that will be discussed: a dedicated signal trigger, out-of-time photon reconstruction and identification, and a detector time resolution measurement. The results of this search include the combination of a related analysis using data collected in 2016 also at sqrt(s) = 13 TeV, corresponding to a combined integrated luminosity of 77.4 fb^-1. The combined results are interpreted in the context of supersymmetry with gauge-mediated supersymmetry breaking, where the neutralino is long-lived and decays to a photon and a gravitino. Limits are presented as a function of the neutralino proper decay length and mass. For neutralino proper decay lengths of 10^1, 10^2, 10^3, and 10^4 cm, masses up to 320, 525, 360, and 215 GeV are excluded at 95% confidence level, respectively. Additionally, a discussion on a high-performance computing upgrade to CMS, known as mkFit, will be presented. mkFit is an on-going effort to exploit highly parallel computer architectures in vectorizing and parallelizing combinatorial Kalman filter charged particle track reconstruction algorithms. The current physics and computational performance of this project will be discussed.
![Performance of Electron Reconstruction and Selection with the CMS Detector in Proton-proton Collisions at [arrow]](https://books.google.com/books/content/images/frontcover/2j6NAQAACAAJ?fife=w80-h100)
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 63
Get Book Here
Book Description
The performance and strategies used in electron reconstruction and selection at CMS are presented based on data corresponding to an integrated luminosity of 19.7 fb-1, collected in proton-proton collisions at [arrow]" = 8 TeV at the CERN LHC. The paper focuses on prompt isolated electrons with transverse momenta ranging from about 5 to a few 100 GeV. A detailed description is given of the algorithms used to cluster energy in the electromagnetic calorimeter and to reconstruct electron trajectories in the tracker. The electron momentum is estimated by combining the energy measurement in the calorimeter with the momentum measurement in the tracker. Benchmark selection criteria are presented, and their performances assessed using Z, [Upsilon], and J/[psi] decays into e++ e- pairs. The spectra of the observables relevant to electron reconstruction and selection as well as their global efficiencies are well reproduced by Monte Carlo simulations. The momentum scale is calibrated with an uncertainty smaller than 0.3%. The momentum resolution for electrons produced in Z boson decays ranges from 1.7 to 4.5%, depending on electron pseudorapidity and energy loss through bremsstrahlung in the detector material.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 1002
Get Book Here
Book Description
The performance of tau-lepton reconstruction and identification algorithms is studied using a data sample of proton-proton collisions at sqrt(s)=7 TeV, corresponding to an integrated luminosity of 36 inverse picobarns collected with the CMS detector at the LHC. The tau leptons that decay into one or three charged hadrons, zero or more short-lived neutral hadrons, and a neutrino are identified using final-state particles reconstructed in the CMS tracker and electromagnetic calorimeter. The reconstruction efficiency of the algorithms is measured using tau leptons produced in Z-boson decays. The tau-lepton misidentification rates for jets and electrons are determined.
Author: You-Hao Chang
Publisher: Springer
ISBN: 9811038244
Category : Science
Languages : en
Pages : 107
Get Book Here
Book Description
This book mainly focuses on the study of photon + 3 jets final state in Proton-Proton Collisions at √s = 7TeV, searching for patterns of two (or more) distinct hard scatterings in the same collision, i.e the so-called Double Parton Scattering (DPS). A new method by using Monte Carlo generators was performed and provides higher order corrections to the description of the Single Parton Scattering (SPS) background. Further it is investigated whether additional contributions from DPS can improve the agreement between the measured data and the Monte Carlo predictions. The current theoretical uncertainties related to the SPS background are found to be larger than expectation. At the same time a rich set of DPS-sensitive measurements is reported for possible further interpretation.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 30
Get Book Here
Book Description
This article documents the performance of the ATLAS muon identification and reconstruction using the LHC dataset recorded at √s=13 TeV in 2015. Using a large sample of J/? → ?? and Z → ?? decays from 3.2 fb-1 of pp collision data, measurements of the reconstruction efficiency, as well as of the momentum scale and resolution, are presented and compared to Monte Carlo simulations. Furthermore, the reconstruction efficiency is measured to be close to 99% over most of the covered phase space (
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 55
Get Book Here
Book Description
The performance of missing transverse energy reconstruction algorithms is presented by our team using√s=8 TeV proton-proton (pp) data collected with the CMS detector. Events with anomalous missing transverse energy are studied, and the performance of algorithms used to identify and remove these events is presented. The scale and resolution for missing transverse energy, including the effects of multiple pp interactions (pileup), are measured using events with an identified Z boson or isolated photon, and are found to be well described by the simulation. Novel missing transverse energy reconstruction algorithms developed specifically to mitigate the effects of large numbers of pileup interactions on the missing transverse energy resolution are presented. These algorithms significantly reduce the dependence of the missing transverse energy resolution on pileup interactions. Furthermore, an algorithm that provides an estimate of the significance of the missing transverse energy is presented, which is used to estimate the compatibility of the reconstructed missing transverse energy with a zero nominal value.
Author: Yi Chen (S.B.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 34
Get Book Here
Book Description
Introduction: The Large Hadron Collider (LHC) located at Geneva, Switzerland, will be the biggest particle accelerator in the world. There are a number of detectors on the LHC ring. The LHCb detector is aimed to study bottom quark physics, which will allow a measurement of the parameters of CP violation in bottom quark productions. The ALICE experiment is specialized in Pb+Pb heavy ion collisions. The ATLAS [3] detector is a general purpose detector, and it will be conducting p+p collision experiments. In addition, the Compact Muon Solenoid (CMS) is currently being commissioned. It will start taking data from as early as late 2008. The detector will be excel in muon detection, but it is also a general purpose detector for p+p and Pb+Pb collsions. The CMS experiment opens up a new window into physics at a unprecedented energy. With the new energy range, a lot of exciting new physics can be examined. The search for the HIGGS boson, which arises from scalar field and is postulated to account for the mass of vector bosons, is one of the main goals of the experiment. The energy range of the LHC is well matched for either confirming its existence or ruling it out. The LHC experiments also want to research on super-symmetry, which potentially explains a lot of open questions for physics beyond the standard model. Although the CMS detector will devote most of its time running proton-proton collisions, one month of each year it will be running lead-lead collisions at center-of-mass energy of 5.5 TeV. Through heavy ion collisions more about the properties of the quark-gluon plasma can be studied, like the viscosity or opacity. In preparation for further studies to the lead-lead collisions, it is interesting to test the basic detector capabilities by studying basic particle reconstruction capabilities. Reconstruction of prompt photon in the heavy ion background has been studied by the MIT heavy ion group last summer, and it leads to the main goal of this thesis. Electrons are one of the main background of the photons, and certainly an important particle type that future studies might need. Inside the CMS detector there will be a roughly constant magnetic field 4.0 Tesla maintained by a superconducting magnet, which allows good measurement of the particle momentum. A slice of the detector is shown in Figure 1. The detector consists of several parts, from inside to outside there are silicon trackers, electromagnetic calorimeter (ECAL), hadronic calorimeter (HCAL), and finally the muon chambers. The tracker is specialized of measuring the momentum of charged particles. The particles will leave a trace on the tracker as they fly through the detector. One important feature about the readout of the tracker is that the output is not binary. Instead, it has an multiple-bit ADC value which allows for better measurement of the direction and better identification of the particle that passes through the tracker. This makes the tracker good for heavy ion events. The electromagnetic and hadronic calorimeters measure energies of different types of particles. Particles such as electrons and photons will deposit most of its energy into the electromagnetic calorimeters, whereas hadrons dump most of their energy into the hadronic calorimeter. The measurement of missing energy in hadronic calorimeter also provides signature of new particles. This study will be focused on the reconstruction of electrons in heavy ion back ground. The reconstructed electrons are then used to show that the reconstruction of the invariant mass of Z0 boson in heavy ion background is possible. The expected number for various particles is listed in section 2. In section 3 the simulated samples used for the study. In the following two sections the reconstruction procedure and the reconstruction properties for electrons. In section 6 the background sources to electrons and the reconstruction of Zo are discussed. Last but not least, additional cuts used for Z0 reconstruction and the results are written in section 7.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
