Top Quark Mass Measurement In The Lepton Jets Channel Using A Matrix Element Method And Textitin Situ Jet Energy Calibration PDF Download
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| Total Pages | : 7 |
| Release | : 2010 |
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Download Top Quark Mass Measurement in the Lepton + Jets Channel Using a Matrix Element Method and \textit{in Situ} Jet Energy Calibration Book in PDF, ePub and Kindle
A precision measurement of the top quark mass m{sub t} is obtained using a sample of t{bar t} events from p{bar p} collisions at the Fermilab Tevatron with the CDF II detector. Selected events require an electron or muon, large missing transverse energy, and exactly four high-energy jets, at least one of which is tagged as coming from a b quark. A likelihood is calculated using a matrix element method with quasi-Monte Carlo integration taking into account finite detector resolution and jet mass effects. The event likelihood is a function of m{sub t} and a parameter [Delta]{sub JES} used to calibrate the jet energy scale in situ. Using a total of 1087 events, a value of m{sub t} = 173.0 ± 1.2 GeV/c2 is measured.
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| Total Pages | : 46 |
| Release | : 2008 |
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Download Top Quark Mass Measurement in the Lepton Plus Jets Channel Using a Modified Matrix Element Method Book in PDF, ePub and Kindle
The authors report a measurement of the top quark mass, m{sub t}, obtained from p{bar p} collisions at (square root)s = 1.96 TeV at the Fermilab Tevatron using the CDF II detector. They analyze a sample corresponding to an integrated luminosity of 1.9 rfb−1. They select events with an electron or muon, large missing transverse energy, and exactly four high-energy jets in the central region of the detector, at least one of which is tagged as coming from a b quark. They calculate a signal likelihood using a matrix element integration method, where the matrix element is modified by using effective propagators to take into account assumptions on event kinematics. The event likelihood is a function of m{sub t} and a parameter JES that determines in situ the calibration of the jet energies. They use a neural network discriminant to distinguish signal from background events. They also apply a cut on the peak value of each event likelihood curve to reduce the contribution of background and badly reconstructed events. Using the 318 events that pass all selection criteria, they find m{sub t} = 172.7 ± 1.8 (stat. + JES) ± 1.2(syst.) GeV/c2.
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| Total Pages | : 9 |
| Release | : 2011 |
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Download Measurement of the Top-quark Mass in the Lepton+jets Channel Using a Matrix Element Technique with the CDF II Detector Book in PDF, ePub and Kindle
A measurement of the top-quark mass is presented using Tevatron data from proton-antiproton collisions at center-of-mass energy √ = 1.96 TeV collected with the CDF II detector. Events are selected from a sample of candidates for production of t{bar t} pairs that decay into the lepton+jets channel. The top-quark mass is measured with an unbinned maximum likelihood method where the event probability density functions are calculated using signal and background matrix elements, as well as a set of parameterized jet-to-parton transfer functions. The likelihood function is maximized with respect to the top-quark mass, the signal fraction in the sample, and a correction to the jet energy scale (JES) calibration of the calorimeter jets. The simultaneous measurement of the JES correction ([Delta]{sub JES}) amounts to an additional in situ jet energy calibration based on the known mass of the hadronically decaying W boson. Using the data sample of 578 lepton+jets candidate events, corresponding to 3.2 fb−1 of integrated luminosity, the top-quark mass is measured to be m{sub t} = 172.4 ± 1.4 (stat + [Delta]{sub JES}) ± 1.3 (syst) GeV/c2.
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| Total Pages | : 169 |
| Release | : 2010 |
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Download A Top Quark Mass Measurement Using a Matrix Element Method Book in PDF, ePub and Kindle
A measurement of the mass of the top quark is presented, using top-antitop pair (t{bar t}) candidate events for the lepton+jets decay channel. The measurement makes use of Tevatron p{bar p} collision data at centre-of-mass energy √s = 1.96 TeV, collected at the CDF detector. The top quark mass is measured by employing an unbinned maximum likelihood method where the event probability density functions are calculated using signal (t{bar t}) and background (W+jets) matrix elements, as well as a set of parameterised jet-to-parton mapping functions. The likelihood function is maximised with respect to the top quark mass, the fraction of signal events, and a correction to the jet energy scale (JES) of the calorimeter jets. The simultaneous measurement of the JES correction ([Delta]{sub JES}) provides an in situ jet energy calibration based on the known mass of the hadronically decaying W boson. Using 578 lepton+jets candidate events corresponding to 3.2 fb−1 of integrated luminosity, the top quark mass is measured to be m{sub t} = 172.4 ± 1.4 (stat+[Delta]{sub JES}) ± 1.3 (syst) GeV=c2, one of the most precise single measurements to date.
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| Total Pages | : 19 |
| Release | : 2011 |
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Download Precise Measurement of the Top-quark Mass from Lepton+jets Events at Book in PDF, ePub and Kindle
We report a measurement of the mass of the top quark in lepton+jets final states of p{bar p} → t{bar t} data corresponding to 2.6 fb−1 of integrated luminosity collected at the D0 experiment at the Fermilab Tevatron Collider. Using a matrix element method, we combine an in situ jet energy calibration with the standard jet energy scale derived in studies of [gamma] + jet and dijet events and employ a novel flavor-dependent jet response correction to measure a top-quark mass of m{sub t} = 176.01 ± 1.64 GeV. Combining this result with a previous result obtained on an independent data set, we measure a top-quark mass of m{sub t} = 174.94 ± 1.49 GeV for a total integrated luminosity of 3.6 fb−1.
| Author | : Brian Mohr |
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| Total Pages | : 5 |
| Release | : 2006 |
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Download Measurement of the Top Quark Mass with a Matrix Element Method in the Lepton Plus Jets Channel at CDF. Book in PDF, ePub and Kindle
The authors present a measurement of the mass of the top quark from p{bar p} collisions at 1.96 TeV observed with the Collider Detector at Fermilab (CDF) at the Fermilab Tevatron Run II. The events have the decay signature of p{bar p} {yields} t{bar t} in the lepton plus jets channel in which at least one jet is identified as coming from a secondary vertex and therefore a b-hadron. The largest systematic uncertainty, the jet energy scale (JES), is convoluted with the statistical error using an in-situ measurement of the hadronic W boson mass. They calculate a likelihood for each event using leading-order t{bar t} and W+jets cross-sections and parameterized parton showering. The final measured top quark mass and JES systematic is extracted from a joint likelihood of the product of individual event likelihoods. From 118 events observed in 680 pb{sup -1} of data, they measure a top quark mass of 174.09 {+-} 2.54 (stat+JES) {+-} 1.35(syst) GeV/c{sup 2}.
| Author | : T. Maruyama |
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| Total Pages | : 18 |
| Release | : 2006 |
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Download Measurement of the Top Quark Mass Using the Template Method in the Lepton Plus Jets Channel with in Situ W ---] J J Calibration at CDF-II. Book in PDF, ePub and Kindle
We report an updated measurement of the top quark mass in the lepton plus jets channel of t{bar t} events from p{bar p} collisions at {radical}s = 1.96 TeV. This measurement uses a dataset with integrated luminosity of 680 pb{sup -1}, containing 360 t{bar t} candidates separated into four subsamples. A top quark mass is reconstructed for each event by using energy and momentum constraints on the top quark pair decay products. We also employ the reconstructed mass of hadronic W boson decays W {yields} jj to constrain in situ the largest systematic uncertainty of the top quark mass measurement: the jet energy scale. Monte Carlo templates of the reconstructed top quark and W boson mass are produced as a function of the true top quark mass and the jet energy scale. The distribution of reconstructed top quark and W boson mass in the data are compared to the Monte Carlo templates using a likelihood fit to obtain: M{sub top} = 173.4 {+-} 2.8 GeV/c{sup 2}.
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| Total Pages | : 177 |
| Release | : 2009 |
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Download Precision Measurement of the Top Quark Mass in the Lepton + Jets Channel Using a Matrix Element Method with Quasi-Monte Carlo Integration Book in PDF, ePub and Kindle
This thesis presents a measurement of the top quark mass obtained from p{bar p} collisions at √s = 1.96 TeV at the Fermilab Tevatron using the CDF II detector. The measurement uses a matrix element integration method to calculate a t{bar t} likelihood, employing a Quasi-Monte Carlo integration, which enables us to take into account effects due to finite detector angular resolution and quark mass effects. We calculate a t{bar t} likelihood as a 2-D function of the top pole mass m{sub t} and [Delta]{sub JES}, where [Delta]{sub JES} parameterizes the uncertainty in our knowledge of the jet energy scale; it is a shift applied to all jet energies in units of the jet-dependent systematic error. By introducing [Delta]{sub JES} into the likelihood, we can use the information contained in W boson decays to constrain [Delta]{sub JES} and reduce error due to this uncertainty. We use a neural network discriminant to identify events likely to be background, and apply a cut on the peak value of individual event likelihoods to reduce the effect of badly reconstructed events. This measurement uses a total of 4.3 fb−1 of integrated luminosity, requiring events with a lepton, large E{sub T}, and exactly four high-energy jets in the pseudorapidity range.
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| Total Pages | : 26 |
| Release | : 2006 |
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Download Measurement of the Top Quark Mass in the Lepton+jets Final State with the Matrix Element Method Book in PDF, ePub and Kindle
We present a measurement of the top quark mass with the Matrix Element method in the lepton+jets final state. As the energy scale for calorimeter jets represents the dominant source of systematic uncertainty, the Matrix Element likelihood is extended by an additional parameter, which is defined as a global multiplicative factor applied to the standard energy scale. The top quark mass is obtained from a fit that yields the combined statistical and systematic jet energy scale uncertainty.
| Author | : Philipp Schieferdecker |
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| Total Pages | : 182 |
| Release | : 2005 |
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Download Measurement of the Top Quark Mass at D0 Run II with the Matrix Element Method in the Lepton+Jets Final State Book in PDF, ePub and Kindle
The mass of the top quark is a fundamental parameter of the Standard Model. Its precise knowledge yields valuable insights into unresolved phenomena in and beyond the Standard Model. A measurement of the top quark mass with the matrix element method in the lepton+jets final state in D0 Run II is presented. Events are selected requiring an isolated energetic charged lepton (electron or muon), significant missing transverse energy, and exactly four calorimeter jets. For each event, the probabilities to originate from the signal and background processes are calculated based on the measured kinematics, the object resolutions and the respective matrix elements. The jet energy scale is known to be the dominant source of systematic uncertainty. The reference scale for the mass measurement is derived from Monte Carlo events. The matrix element likelihood is defined as a function of both, m{sub top} and jet energy scale JES, where the latter represents a scale factor with respect to the reference scale. The top mass is obtained from a two-dimensional correlated fit, and the likelihood yields both the statistical and jet energy scale uncertainty. Using a dataset of 320 pb{sup -1} of D0 Run II data, the mass of the top quark is measured to be: m{sub top}{sup {ell}+jets} = 169.5 {+-} 4.4(stat. + JES){sub -1.6}{sup +1.7}(syst.) GeV; m{sub top}{sup e+jets} = 168.8 {+-} 6.0(stat. + JES){sub -1.9}{sup +1.9}(syst.) GeV; m{sub top}{sup {mu}+jets} = 172.3 {+-} 9.6(stat.+JES){sub -3.3}{sup +3.4}(syst.) GeV. The jet energy scale measurement in the {ell}+jets sample yields JES = 1.034 {+-} 0.034, suggesting good consistency of the data with the simulation. The measurement forecasts significant improvements to the total top mass uncertainty during Run II before the startup of the LHC, as the data sample will grow by a factor of ten and D0's tracking capabilities will be employed in jet energy reconstruction and flavor identification.
