Measurement of Track-based Missing Transverse Momentum in Proton-proton Collisions at √s PDF Download
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Author: Claire Alexandra Lee
Publisher:
ISBN:
Category : Collisions (Nuclear physics)
Languages : en
Pages : 139
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Book Description
Author: Claire Alexandra Lee
Publisher:
ISBN:
Category : Collisions (Nuclear physics)
Languages : en
Pages : 139
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
A dedicated search is presented for new phenomena in inclusive eight- and ten-jet final states with low missing transverse momentum, with and without identification of jets originating from b quarks. The analysis is based on data from proton-proton collisions corresponding to an integrated luminosity of 19.6 inverse femtobarns collected with the CMS detector at the LHC at sqrt(s) = 8 TeV. The dominant multijet background expectations are obtained from low jet multiplicity control samples. Data agree well with the standard model background predictions, and limits are set in several benchmark models. Colorons (axigluons) with masses between 0.6 and 0.75 (up to 1.15) TeV are excluded at 95% confidence level. Similar exclusion limits for gluinos in R-parity violating supersymmetric scenarios are from 0.6 up to 1.1TeV. These results comprise the first experimental probe of the coloron and axigluon models in multijet final states.
Author: Clara Elizabeth Kuehn
Publisher:
ISBN:
Category : Pions
Languages : en
Pages : 484
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Author: Zhelun Li
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Many interesting physical processes produce non-interacting particles that could only be measured using the missing transverse momentum. The increase of the proton beam intensity in the Large Hadron Collider (LHC) provides sensitivity to rare physics processes while inevitably increasing the number of simultaneous proton collisions in each event. The missing transverse momentum (MET) is a variable of great interest, defined as the negative sum of the transverse momentum of all visible particles. The precision of the MET determination deteriorates as the complexity of the recorded data escalates. Given the current complexity of data analysis, a new algorithm is developed to effectively determine the MET. Several well-understood physics processes were used to test the effectiveness of the newly designed algorithm. The performance of the new algorithm is also compared to that of the standard algorithm used in the ATLAS experiment.
Author: Shingo Kazama
Publisher: Springer
ISBN: 4431556575
Category : Science
Languages : en
Pages : 155
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Book Description
In this book, the anomaly mediated supersymmetry breaking (AMSB) model is explored by searching for charged winos with their subsequent decays collected with the ATLAS detector at the Large Hadron Collider (LHC). The author develops a new method, called “re-tracking,” to detect charged winos that decay before reaching the Semiconductor Tracker (SCT) detector. Because the nominal tracking algorithm at the ATLAS experiment requires at least seven successive hits in the inner tracking system, the sensitivity to charged winos having a fraction of a nanosecond in the past analysis was therefore limited. However, re-tracking requires a minimum of three pixel hits and provides a fully efficient tracking capability for charged winos traversing the pixel detector, resulting in around about 100 times greater efficiency for charged winos with a lifetime ~0.2 ns longer than that in past searches. Signal topology is characterized by a jet with large transverse momentum (pT), large missing transverse energy, and a high-pT disappearing track. There are three types of back ground tracks: interacting hadron tracks, charged leptons, and tracks with mismeasured pT. A background estimation based on the Monte Carlo (MC) simulation suffers from large uncertainties due to poor statistics and has difficulty simulating the properties of background tracks. Therefore, a data-driven approach has been developed by the author of the book to estimate the background track-pT spectrum. No significant excess above the background expectation is observed for candidate tracks with large transverse momentum, and constraints on the AMSB model are obtained. The author shows that in the AMSB model, a charged wino mass below 270 GeV is excluded at 95 % confidence level, which also directly constrains the mass of wino dark matter.
Author: Douglas W. Rank
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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A measurement of the underlying event activity is performed for proton-proton collisions at a center of mass energy of 13 TeV using the Compact Muon Solenoid detector. The azimuthal angle of the highest transverse-momentum track is used to split the azimuthal plane into three regions of equal area: Toward, Away, and Transverse. The Transverse region is further subdivided into a region of maximal activity and a region of minimal activity. The activity is quantified by the number of tracks and the sum of their transverse momenta in each region. Comparisons are made with previous results obtained at 0.3, 0.9, 1.96, and 7 TeV. These combined results can be used to refine and improve Monte Carlo predictions of the underlying event activity at current and higher energies which will lead to the improved modelling of proton-proton collisions leading to more precise measurements at the Large Hadron Collider.
Author: Klemens Müller
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 38
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A search for new physics is performed in multijet events with large missing transverse momentum produced in proton-proton collisions at $\sqrt{s}$ = 8 TeV using a data sample corresponding to an integrated luminosity of 19.5 fb−1collected with the CMS detector at the LHC. The data sample is divided into three jet multiplicity categories (3-5, 6-7, and ≥8 jets), and studied further in bins of two variables: the scalar sum of jet transverse momenta and the missing transverse momentum. The observed numbers of events in various categories are consistent with backgrounds expected from standard model processes. Exclusion limits are presented for several simplified supersymmetric models of squark or gluino pair production.
Author: Valerio Rossetti
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 61
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Distributions of transverse momentum pTll and the related angular variable $\phi ^*_{\eta }$ of Drell-Yan lepton pairs are measured in 20.3 fb-1 of proton-proton collisions at √s=8 TeV with the ATLAS detector at the LHC. Measurements in electron-pair and muon-pair final states are corrected for detector effects and combined. Compared to previous measurements in proton[Gamma]Çôproton collisions at √s=7 TeV these new measurements benefit from a larger data sample and improved control of systematic uncertainties. Measurements are performed in bins of lepton-pair mass above, around and below the Z -boson mass peak. The data are compared to predictions from perturbative and resummed QCD calculations. For values of $\phi ^*_{\eta }$
