Measurements Of Jet Multiplicity And Differential Production Cross Sections Of Z Jets Events In Proton Proton Collisions At U221a S
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Measurements Of Jet Multiplicity And Differential Production Cross Sections Of Z Jets Events In Proton Proton Collisions At U221a S
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Author :
language : en
Publisher:
Release Date : 2015
Measurements Of Jet Multiplicity And Differential Production Cross Sections Of Z Jets Events In Proton Proton Collisions At U221a S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
Measurements of differential cross sections are presented for the production of a Z boson and at least one hadronic jet in proton-proton collisions at √s = 7 TeV, recorded by the CMS detector, using a data sample corresponding to an integrated luminosity of 4.9 inverse femtobarns. The jet multiplicity distribution is measured for up to six jets. The differential cross sections are measured as a function of jet transverse momentum and pseudorapidity for the four highest transverse momentum jets. The distribution of the scalar sum of jet transverse momenta is also measured as a function of the jet multiplicity. The measurements are compared with theoretical predictions at leading and next-to-leading order in perturbative QCD.
Measurements Of Differential Cross Sections For Associated Production Of A W Boson And Jets In Proton Proton Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2016
Measurements Of Differential Cross Sections For Associated Production Of A W Boson And Jets In Proton Proton Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Differential cross sections for a W boson produced in association with jets are measured in a data sample of proton-proton collisions at a center-of-mass energy of 8 TeV recorded with the CMS detector and corresponding to an integrated luminosity of 19.6 inverse femtobarns. The W bosons are identified through their decay mode W to mu nu. The cross sections are reported as functions of jet multiplicity, transverse momenta, and the scalar sum of jet transverse momenta (HT) for different jet multiplicities. Distributions of the angular correlations between the jets and the muon are examined, as well as the average number of jets as a function of HT and as a function of angular variables. The measured differential cross sections are compared with tree-level and higher-order recent event generators, as well as next-to-leading-order and next-to-next-to-leading-order theoretical predictions. The agreement of the generators with the measurements builds confidence in their use for the simulation of W+jets background processes in searches for new physics at the LHC.
Measurements Of Differential Cross Sections Of Z Gamma Jets X Events In Proton Anti Proton Collisions At S 1 2
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Author :
language : en
Publisher:
Release Date : 2009
Measurements Of Differential Cross Sections Of Z Gamma Jets X Events In Proton Anti Proton Collisions At S 1 2 written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
We present cross section measurements for Z/[gamma]* + jets + X production, differential in the transverse momenta of the three leading jets. The data sample was collected with the D0 detector at the Fermilab Tevatron p{bar p} collider at a center-of-mass energy of 1.96 TeV and corresponds to an integrated luminosity of 1 fb−1. Leading and next-to-leading order perturbative QCD predictions are compared with the measurements, and agreement is found within the theoretical and experimental uncertainties. We also make comparisons with the predictions of four event generators. Two parton-shower-based generators show significant shape and normalization differences with respect to the data. In contrast, two generators combining tree-level matrix elements with a parton shower give a reasonable description of the shapes observed in data, but the predicted normalizations show significant differences with respect to the data, reflecting large scale uncertainties. For specific choices of scales, the normalizations for either generator can be made to agree with the measurements.
Measurements Of Differential Cross Sections Of Z Gamma Jets X Events In Proton Anti Proton Collisions At S
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Author :
language : en
Publisher:
Release Date : 2009
Measurements Of Differential Cross Sections Of Z Gamma Jets X Events In Proton Anti Proton Collisions At S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
We present cross section measurements for Z/?* + jets + X production, differential in the transverse momenta of the three leading jets. The data sample was collected with the D0 detector at the Fermilab Tevatron p{bar p} collider at a center-of-mass energy of 1.96 TeV and corresponds to an integrated luminosity of 1 fb−1. Leading and next-to-leading order perturbative QCD predictions are compared with the measurements, and agreement is found within the theoretical and experimental uncertainties. We also make comparisons with the predictions of four event generators. Two parton-shower-based generators show significant shape and normalization differences with respect to the data. In contrast, two generators combining tree-level matrix elements with a parton shower give a reasonable description of the shapes observed in data, but the predicted normalizations show significant differences with respect to the data, reflecting large scale uncertainties. For specific choices of scales, the normalizations for either generator can be made to agree with the measurements.
Studying Z Jet Production In Proton Antiproton Collisions At U221a S
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language : en
Publisher:
Release Date : 2009
Studying Z Jet Production In Proton Antiproton Collisions At U221a S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
The production of jets in association with a Z/?* boson is an example of an important class of processes at hadron colliders, namely vector boson + jet (V + jet) production. Comparisons of measurements of this class of processes with theory predictions constitute an important, fundamental test of the Standard Model of particle physics, and of the theory of QCD in particular. While having a smaller cross section than other V +jet processes, Z/?*(→ e+e-) + jets production, with Z/?* → e+e-/?+?-, has a distinct experimental signature allowing for measurements characterized by low backgrounds and a direct, precise measurement of the properties of the decay products of the Z/?* boson. In this thesis, several new measurements of the properties of jets produced in association with a Z/?* boson in p$ar{p}$ collisions at √s = 1.96 TeV are presented. The cross section for Z/?*(→ e+e-) + N jet production (N ≤ 3) is measured, differential in the transverse momentum of the Nth jet in the event, normalized to the inclusive Z/?* cross section. Also, the cross section for Z/?*(→e+e-) + N jets (N ≥ 1) is measured, differential in the difference in azimuthal angle between the di-electron system and any jet in the event, normalized to unity. The data used in the measurements were collected by the D0 experiment located at the Tevatron Collider of the Fermi National Accelerator Laboratory and correspond to an integrated luminosity of 1.04 fb-1. The measured jet transverse momentum spectra are compared with the predictions of perturbative calculations at the next-to-leading order in the strong coupling constant. Given the low sensitivity of the calculations to model parameters, these comparisons represent a stringent test of perturbative QCD. One of the main goals currently being pursued in particle physics is the discovery of the only particle predicted by the Standard Model which has so far no been detected experimentally, namely the Higgs boson. It is assumed that the ATLAS and CMS experiments located at the Large Hadron Collider (LHC), a proton-proton collider at √s = 14 TeV, will be able to detect the Higgs boson, or rule out its existence, within the next few years. The collisions delivered by the LHC will also be used to perform a long range of searches for other new particles, for instance particles predicted by models based on the principle of supersymmetry. The associated production of vector bosons with jets has relatively large production rates at the LHC and can produce a long list of different final states which can include charged leptons, missing transverse energy, as well as light- and heavy-flavour jets. This makes V + jet production a major source of background events to many searches for new particles. Most techniques used for estimating the expected number of background events to searches rely on passing the stable final-state particles of simulated hadron collisions generated using a so-called event generator code, through a simulation of the experimental detector system. The development of event generators which are capable of reliably predicting the properties of jets produced in association with a core process, e.g. the production of a vector boson, has been the subject of a large amount of research activity during the last ten years. These efforts have led to the appearance of the CKKW and MLM algorithms which are implemented in several event generators, among them SHERPA and ALPGEN + PYTHIA. The large data sample collected by the D0 experiment during Run II offers an excellent opportunity for validating these new event generators against experimental measurements of V + jet production. As argued above, the Z/?*(→ e+e-) + jets process offers the combination of a clean experimental signature and large production rates, making it the process of choice for these studies.
Differential Cross Section Measurements For The Production Of A W Boson In Association With Jets In Proton Proton Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2014
Differential Cross Section Measurements For The Production Of A W Boson In Association With Jets In Proton Proton Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
Our measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. Furthermore, the data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb-1. The measured cross sections are compared to predictions from Monte Carlo generators, MADGRAPH + PYTHIAand SHERPA, and to next-to-leading-order calculations from BLACKHAT + SHERPA. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.
Differential Cross Section Measurements For The Production Of A W Boson In Association With Jets In Proton U2013 Proton Collisions At U221a S
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Author :
language : en
Publisher:
Release Date : 2014
Differential Cross Section Measurements For The Production Of A W Boson In Association With Jets In Proton U2013 Proton Collisions At U221a S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
Our measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. Furthermore, the data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb-1. The measured cross sections are compared to predictions from Monte Carlo generators, MADGRAPH + PYTHIAand SHERPA, and to next-to-leading-order calculations from BLACKHAT + SHERPA. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.
Measurements Of The Associated Production Of A Z Boson And B Jets In Pp Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2016
Measurements Of The Associated Production Of A Z Boson And B Jets In Pp Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Measurements of the associated production of a Z boson with at least one jet originating from a b quark in proton-proton collisions at $\sqrt{s}$ = 8 TeV are presented. Differential cross sections are measured with data collected by the CMS experiment corresponding to an integrated luminosity of 19.8 inverse femtobarns. Z bosons are reconstructed through their decays to electrons and muons. Cross sections are measured as a function of observables characterizing the kinematics of the b jet and the Z boson. Ratios of differential cross sections for the associated production with at least one b jet to the associated production with any jet are also presented. The production of a Z boson with two b jets is investigated, and differential cross sections are measured for the dijet system. Results are compared to theoretical predictions, testing two different flavour schemes for the choice of initial-state partons.
Measurements Of The Differential Production Cross Sections For A Z Boson In Association With Jets In Pp Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2016
Measurements Of The Differential Production Cross Sections For A Z Boson In Association With Jets In Pp Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Cross sections for the production of a Z boson in association with jets in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}$=8 TeV are measured using a data sample collected by the CMS experiment at the LHC corresponding to 19.6 inverse femtobarns. Differential cross sections are presented as functions of up to three observables that describe the jet kinematics and the jet activity. Correlations between the azimuthal directions and the rapidities of the jets and the Z boson are studied in detail. The predictions of a number of multileg generators with leading or next-to-leading order accuracy are compared with the measurements. The comparison shows the importance of including multi-parton contributions in the matrix elements and the improvement in the predictions when next-to-leading order terms are included.
Measurement Of The Production And Differential Cross Sections Of W W Bosons In Association With Jets In P Bar P Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2015
Measurement Of The Production And Differential Cross Sections Of W W Bosons In Association With Jets In P Bar P Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
In this study, we present a measurement of the W-boson-pair production cross section in pp¯ collisions at 1.96 TeV center-of-mass energy and the first measurement of the differential cross section as a function of jet multiplicity and leading-jet energy. The W+W– cross section is measured in the final state comprising two charged leptons and neutrinos, where either charged lepton can be an electron or a muon. Using data collected by the CDF experiment corresponding to 9.7 fb–1 of integrated luminosity, a total of 3027 collision events consistent with W+W– production are observed with an estimated background contribution of 1790±190 events. The measured total cross section is ?(pp¯→W+W–) = 14.0 ± 0.6(stat)+1.2–1.0 (syst)±0.8 (lumi) pb, consistent with the standard model prediction.