Download or read book Measurement of Track based Missing Transverse Momentum in Proton proton Collisions at s written by Claire Alexandra Lee and published by . This book was released on 2014 with total page 139 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Search for New Physics in Events with High Jet Multiplicity and Low Missing Transverse Momentum in Proton proton Collisions at sqrt s written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Measurement of the Leading Charged Particle Charge Ratios in High Transverse Momentum Proton proton and Pion proton Collisions written by Clara Elizabeth Kuehn and published by . This book was released on 1984 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Development of Missing Transverse Momentum Reconstruction with the ATLAS Detector Using the PUfit Algorithm in Pp Collisions at 13 TeV written by Zhelun Li and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Search for Charginos Nearly Mass Degenerate with the Lightest Neutralino written by Shingo Kazama and published by Springer. This book was released on 2015-10-22 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book A Study of the Underlying Event at 13 TeV Using the Leading Track written by Douglas W. Rank and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Measurement of the Transverse Momentum Distribution of Z Bosons in Proton proton Collisions at Sqrt s written by Klemens Müller and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Search for New Physics in the Multijet and Missing Transverse Momentum Final State in Proton proton Collisions at sqrt s written by and published by . This book was released on 2014 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Search for New Phenomena in Events with One Energetic Jet and Large Missing Transverse Momentum in Proton proton Collisions at s written by Valerio Rossetti and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurement of the Transverse Momentum and phi eta Distributions of Drell Yan Lepton Pairs in Proton proton Collisions at sqrt s written by and published by . This book was released on 2016 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 $\phi ^*_{\eta }$

Download or read book Measurement of the Cross Section of High Transverse Momentum u2192 Bb u00AF Production in Proton u2013 proton Collisions at u221A s written by and published by . This book was released on 2014 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Letter reports the observation of a high transverse momentum Z → bb¯ signal in proton–proton collisions at √s = 8 TeV and the measurement of its production cross section. The data analysed were collected in 2012 with the ATLAS detector at the LHC and correspond to an integrated luminosity of 19.5 fb–1. The Z → bb¯ decay is reconstructed from a pair of b-tagged jets, clustered with the anti-kt jet algorithm with R=0.4, that have low angular separation and form a dijet with pT > 200 GeV. The signal yield is extracted from a fit to the dijet invariant mass distribution, with the dominant, multi-jet background mass shape estimated by employing a fully data-driven technique that reduces the dependence of the analysis on simulation. The fiducial cross section is determined to be ?fidZ →bb¯ = 2.02 ± 0.20 (stat.) ± 0.25 (syst.) ± 0.06 (lumi.) pb = 2.02 ± 0.33 pb, in agreement with next-to-leading-order theoretical predictions.

Download or read book Search for New Phenomena in Ttbar Events with Large Missing Transverse Momentum in Proton Proton Collisions at Sqrt s written by and published by . This book was released on 2013 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurement of Z Boson Transverse Momentum in Proton Anti proton Collisions at S 1 2 written by and published by . This book was released on 2007 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation describes a measurement of the shape of the boson transverse momentum distribution in p{bar p} 2!Z/[gamma]* 2!ee− + X events at a center-of-mass energy of 1.96 TeV. The measurement is made for events with electron-positron mass between 70

Download or read book Measurement of the Prompt Double J psi Production Cross Section in Pp Collisions at Sqrt s written by Andrew David York and published by . This book was released on 2013 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt: The simultaneous production of two J/psi mesons has been significantly observed in proton-proton collisions at a center-of-mass energy of 7 TeV with the CMS detector. The two J/psi mesons are fully reconstructed in their decay to muons. The signal yield is extracted with an extended maximum likelihood fit based on four event variables. A method was developed to correct for detector acceptances and efficiencies based on the measured momenta of the J/psi and their decay muons to maintain the least model dependence possible. The measurement is performed in an acceptance region defined by the individual J/psi transverse momentum and rapidity. From the measured signal yield of 446 events corresponding to an integrated luminosity of 4:7 inverse femtobarn. The total cross section is found to be 1:49 nanobarn, with 0:07 statistical and 0:13 nb systematic error, and unpolarizaed production was assumed. Most predictions for particle production at the LHC assume dominance of single parton interaction for proton-proton collisions, which can be tested with the final state measured in this analysis. The differential cross section is measured in bins of the double J/psi invariant mass, the double J/psi transverse momentum, and the absolute difference in rapidity of the two J/psi. The reconstruction of the four charged muon trajectories heavily relies on the Pixel subdetector located close to the beampipe. Systematic studies with cosmic muons and tracks from collision events are presented. The development of the Pixel RawToDigi package, data quality monitoring packages, commissioning studies of Pixel data and tracks in first collisions, and realistic simulations of decay signals in the pixel subdetector were all performed as a part of this dissertation work.

Download or read book Measurement of Z Boson Transverse Momentum in Proton antiproton Collisions at Sqrt s written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurement of the Transverse Momentum Spectra of Weak Vector Bosons Produced in Proton proton Collisions at sqrt s written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The transverse momentum spectra of weak vector bosons are measured in the CMS experiment at the LHC. The measurement uses a sample of proton-proton collisions at sqrt(s) = 8 TeV, collected during a special low-luminosity running that corresponds to an integrated luminosity of 18.4 inverse-picobarns. The production of W bosons is studied in both electron and muon decay modes, while the production of Z bosons is studied using only the dimuon decay channel. The ratios of W- to W+ and Z to W differential cross sections are also measured. The measured differential cross sections and ratios are compared with theoretical predictions up to next-to-next leading order in QCD.

Download or read book Search for New Physics in Same sign Dilepton Events in Proton proton Collisions at u221A s written by and published by . This book was released on 2016 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for new physics is performed using events with two isolated same-sign leptons, two or more jets, and missing transverse momentum. The results are based on a sample of proton-proton collisions at a center-of-mass energy of 13 TeV recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 2.3 fb1. Multiple search regions are defined by classifying events in terms of missing transverse momentum, the scalar sum of jet transverse momenta, the transverse mass associated with a W boson candidate, the number of jets, the number of b quark jets, and the transverse momenta of the leptons in the event. The analysis is sensitive to a wide variety of possible signals beyond the standard model. No excess above the standard model background expectation is observed. Constraints are set on various supersymmetric models, with gluinos and bottom squarks excluded for masses up to 1300 and 680 GeV, respectively, at the 95% confidence level. Upper limits on the cross sections for the production of two top quark-antiquark pairs (119 fb) and two same-sign top quarks (1.7 pb) are also obtained. Furthermore, selection efficiencies and model independent limits are provided to allow further interpretations of the results.