Download or read book Forward backward Asymmetry of Drell Yan Lepton Pairs in Pp 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 measurement of the forward-backward asymmetry $A_{\mathrm{FB}}$ of oppositely charged lepton pairs ($\mu\mu$ and $\mathrm{ ee } $) produced via $\mathrm{ Z }/\gamma^*$ boson exchange in pp collisions at $\sqrt{s} =$ 8 TeV is presented. The data sample corresponds to an integrated luminosity of 19.7 fb$^{-1}$ collected with the CMS detector at the LHC. The measurement of $A_{\mathrm{FB}}$ is performed for dilepton masses between 40 GeV and 2 TeV and for dilepton rapidity up to 5. The $A_{\mathrm{FB}}$ measurements as a function of dilepton mass and rapidity are compared with the standard model predictions.

Download or read book Measurement of the Double differential High mass Drell Yan Cross Section in Pp 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: This study presents a measurement of the double-differential cross section for the Drell-Yan Z/[gamma]* → l+l- and photon-induced [gamma][gamma] → l+l- processes where l is an electron or muon. The measurement is performed for invariant masses of the lepton pairs, mll, between 116 GeV and 1500 GeV using a sample of 20.3 fb-1 of pp collisions data at centre-of-mass energy of √s = 8 TeV collected by the ATLAS detector at the LHC in 2012. The data are presented double differentially in invariant mass and absolute dilepton rapidity as well as in invariant mass and absolute pseudorapidity separation of the lepton pair. The single-differential cross section as a function of mll is also reported. The electron and muon channel measurements are combined and a total experimental precision of better than 1% is achieved at low mll. A comparison to next-to-next-to-leading order perturbative QCD predictions using several recent parton distribution functions and including next-to-leading order electroweak effects indicates the potential of the data to constrain parton distribution functions. In particular, a large impact of the data on the photon PDF is demonstrated.

Download or read book Measurement of the Forward backward Asymmetry of Electron and Muon Pair production in Pp Collisions at sqrt s written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents measurements from the ATLAS experiment of the forward-backward asymmetry in the reaction pp 2!Z/[gamma] * 2!l + l -, with l being electrons or muons, and the extraction of the effective weak mixing angle. The results are based on the full set of data collected in 2011 in pp collisions at the LHC at \(\sqrt{s}=7 \) TeV, corresponding to an integrated luminosity of 4.8 fb-1. The measured asymmetry values are found to be in agreement with the corresponding Standard Model predictions. The combination of the muon and electron channels yields a value of the effective weak mixing angle of sin2 [theta] eff lept =0.2308"0.0005(stat.)"0.0006(syst.)"0.0009(PDF), where the first uncertainty corresponds to data statistics, the second to systematic effects and the third to knowledge of the parton density functions. This result agrees with the current world average from the Particle Data Group fit.

Download or read book Measurement of the Forward backward Asymmetry of Electron and Muon Pair production in Pp Collisions at u221A s written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This study presents measurements from the ATLAS experiment of the forward-backward asymmetry in the reaction pp → Z/? * →l+l-, with l being electrons or muons, and the extraction of the effective weak mixing angle. The results are based on the full set of data collected in 2011 in pp collisions at the LHC at ( sqrt{s}=7 ) TeV, corresponding to an integrated luminosity of 4.8 fb-1. The measured asymmetry values are found to be in agreement with the corresponding Standard Model predictions. The combination of the muon and electron channels yields a value of the effective weak mixing angle of sin2 ?efflept =0.2308±0.0005(stat.)±0.0006(syst.)±0.0009(PDF), where the first uncertainty corresponds to data statistics, the second to systematic effects and the third to knowledge of the parton density functions. This result agrees with the current world average from the Particle Data Group fit.

Download or read book Measurement of the Drell Yan Differential Cross Section and Forward Backward Asymmetry in Proton Anti proton E E Events Using the D0 Detector written by Raymond Gelhaus and published by . This book was released on 2005 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present measurements of the inclusive Drell-Yan e{sup +}e{sup -} differential cross section (d{sigma}/dM{sub e{sup +}e{sup -}}) and forward-backward asymmetry (A{sub FB}) as a function of the dielectron invariant mass over the range 70-400 GeV/c{sup 2}. The data sample consists of 177.3 pb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV collected by the D0 detector. The results are consistent with the predictions of the standard model.

Download or read book Lepton Pair Production and the Modified Drell Yan Mechanism in High Energy Unpolarized and Polarized Pp and Antipp Collisions written by and published by . This book was released on 1977 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A modified Drell-Yan mechanism for the inclusive dilepton pair production in hadronic reactions is studied, and the significance of comparing high energy unpolarized and polarized pp and anti pp collisions is discussed. The required beams are currently in proposal at FNAL and CERN.

Download or read book Measurement of Drell Yan Longitudinal Double Spin Asymmetry in Polarized P P Collisions at PHENIX written by Gonaduwage Darshana Nadeeshan Perera and published by . This book was released on 2016 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: Analysis of the Drell-Yan process in high energy polarized proton-proton collisions is a unique method for probing the proton spin structure. Measurement of the longitudinal double spin asymmetry (A[subscript LL]) in the Drell-Yan process provides clean access to the anti-quark helicity distributions without involving quark fragmentation functions. In the PHENIX experiment at RHIC, the Forward Silicon Vertex Detector (FVTX), together with forward muon spectrometers, allows us to study the Drell-Yan process by detecting the muon pairs in the forward region (1.2

Download or read book Drell Yan Lepton Pair Azimuthal Asymmetry in Hadronic Processes written by and published by . This book was released on 2009 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: We study the azimuthal asymmetry in the Drell-Yan lepton pair production in hadronic scattering processes at moderate transverse momentum region, taking into account the contributions from the twist-three quark-gluon correlations from the unpolarized hadrons. The contributions are found to dominate the asymmetry, and are not power suppressed by qt/Q at small qt where qt and Q are the transverse momentum and invariant mass of the lepton pair. Accordingly, the Lam-Tung relation will be violated at this momentum region, and its violation depends on the twist-three functions. However, at large transverse momentum qt~;;Q, the Lam-Tung relation still holds because all corrections are power suppressed by Lambda2/qt2 ~;; Lambda2/Q2 where Lambda is the typical nonperturbative scale.

Download or read book Initial State Interactions in the Unpolarized Drell Yan Process written by and published by . This book was released on 2002 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: We show that initial-state interactions contribute to the cos 2[phi] distribution in unpolarized Drell-Yan lepton pair production p p and p {bar p} 2!ll− X, without suppression. The asymmetry is expressed as a product of chiral-odd distributions h1{sup {perpendicular}} (x1, p{sub {perpendicular}}2) x {bar h}1{sup {perpendicular}} (x2, k{sub {perpendicular}}2), where the quark-transversity function h1{sup {perpendicular}}(x, p{sub {perpendicular}}2) is the transverse momentum dependent, light-cone momentum distribution of transversely polarized quarks in an unpolarized proton. We compute this (naive) T-odd and chiral-odd distribution function and the resulting cos 2[psi]asymmetry explicitly in a quark-scalar diquark model for the proton with initial-state gluon interaction. In this model the function h1{sup {perpendicular}} (x1, p{sub {perpendicular}}2) equals the T-odd (chiral-even) Sivers effect function f{sub 1T}{sup {perpendicular}}(x, p{sub {perpendicular}}2). This suggests that the single-spin asymmetries in the SIDIS and the Drell-Yan process are closely related to the cos 2[phi] asymmetry of the unpolarized Drell-Yan process, since all can arise from the same underlying mechanism. This provides new insight regarding the role of quark and gluon orbital angular momentum as well as that of initial- and final-state gluon exchange interactions in hard QCD processes.

Download or read book Transverse angular distributions of Drell Yan dilepton pairs from 8 6 fb 1 of p bar p collisions at sqrt s written by John Keith Sebastian Beddow and published by . This book was released on 2012 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurements of the t bar t Charge Asymmetry Using the Dilepton Decay Channel in Pp Collisions at sqrt s written by and published by . This book was released on 2014 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt: The t t-bar charge asymmetry in proton-proton collisions at $\sqrt{s} =$ 7 TeV is measured using the dilepton decay channel (ee, e mu, or mu mu). The data correspond to a total integrated luminosity of 5.0 inverse femtobarns, collected by the CMS experiment at the LHC. The t t-bar and lepton charge asymmetries, defined as the differences in absolute values of the rapidities between the reconstructed top quarks and antiquarks and of the pseudorapidities between the positive and negative leptons, respectively, are measured to be Ac = -0.010 +/- 0.017 (stat.) +/- 0.008 (syst.) and Aclep = 0.009 +/- 0.010 (stat.) +/- 0.006 (syst). The lepton charge asymmetry is also measured as a function of the invariant mass, rapidity, and transverse momentum of the t t-bar system. All measurements are consistent with the expectations of the standard model.

Download or read book Measurement of the Differential and Double differential Drell Yan Cross Sections in Proton proton Collisions at Sqrt s written by and published by . This book was released on 2013 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements of the differential and double-differential Drell-Yan cross sections are presented using an integrated luminosity of 4.5(4.8) inverse femtobarns in the dimuon (dielectron) channel of proton-proton collision data recorded with the CMS detector at the LHC at sqrt{s} = 7 TeV. The measured inclusive cross section in the Z-peak region (60-120 GeV) is \sigma(\ell \ell) = 986.4 +/- 0.6 (stat.) +/- 5.9 (exp. syst.) +/- 21.7 (th. syst.) +/- 21.7 (lum.) pb for the combination of the dimuon and dielectron channels. Differential cross sections $d\sigma/dm$ for the dimuon, dielectron, and combined channels are measured in the mass range 15 to 1500 GeV and corrected to the full phase space. Results are also presented for the measurement of the double-differential cross section d2̂\sigma/dm d.

Download or read book Measurement of the Production Cross Section for Pairs of Isolated Photons in Pp Collisions at Sqrt s written by and published by . This book was released on 2012 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: The integrated and differential cross sections for the production of pairs of isolated photons is measured in proton-proton collisions at a centre-of-mass energy of 7 TeV with the CMS detector at the LHC. A data sample corresponding to an integrated luminosity of 36 inverse picobarns is analysed. A next-to-leading-order perturbative QCD calculation is compared to the measurements. A discrepancy is observed for regions of the phase space where the two photons have an azimuthal angle difference, $\Delta(\phi)$, less than approximately 2.8.

Download or read book A Measurement of the Forward backward Asymmetry and sine Squared Theta W from the Process ZO Goes to muon muon at square Root Of S written by Leigh Ann Markosky and published by . This book was released on 1992 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hadronic Production of Massive Lepton Pairs written by and published by . This book was released on 1982 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A review is presented of recent experimental and theoretical progress in studies of the production of massive lepton pairs in hadronic collisions. I begin with the classical Drell-Yan annihilation model and its predictions. Subsequently, I discuss deviations from scaling, the status of the proofs of factorization in the parton model, higher-order terms in the perturbative QCD expansion, the discrepancy between measured and predicted yields (K factor), high-twist terms, soft gluon effects, transverse-momentum distributions, implications for weak vector boson (W/sup + -/ and Z°) yields and production properties, nuclear A dependence effects, correlations of the lepton pair with hadrons in the final state, and angular distributions in the lepton-pair rest frame.

Download or read book Measurement of the t bar t Production Cross Section in Pp Collisions at sqrt s written by and published by . This book was released on 2014 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top-quark pair production cross section is measured in final states with one electron or muon and one hadronically decaying [tau] lepton from the process $t\bar{t}$ to (l[nu]l) ([tau][nu][tau]) $b\bar{b}$, where l = e, [mu]. The data sample corresponds to an integrated luminosity of 19.6 fb-1 collected with the CMS detector in proton-proton collisions at $\sqrt{s}$ =8 TeV. The measured cross section [sigma]$t\bar{t}$ = 257 ± 3 (stat) ± 24 (syst) ± 7 (lumi) pb, assuming a top-quark mass of 172.5 GeV, is consistent with the standard model prediction.