Measurements of the muon charge asymmetry in inclusive pp to WX production at sqrt(s) = 7 TeV are presented. The data sample corresponds to an integrated luminosity of 4.7 inverse femtobarns recorded with the CMS detector at the LHC. With a sample of more than twenty million W to mu nu events, the statistical precision is greatly improved in comparison to previous measurements. These new results provide additional constraints on the parton distribution functions of the proton in the range of the Bjorken scaling variable x from 10E-3 to 10E-1. These measurements and the recent CMS measurement of associated W + charm production are used together with the cross sections for inclusive deep inelastic ep scattering at HERA in a next-to-leading-order QCD analysis. The determination of the valence quark distributions is improved, and the strange-quark distribution is probed directly through the leading-order process g + s to W + c in proton-proton collisions at the LHC.
Summary of the final results for muon charge asymmetry $\mathcal{A}$ with the muon $p_{T}>25$ GeV. The first uncertainty is statistical and the second is systematic. The theoretical predictions are obtained using the FEWZ 3.1 MC tool interfaced with the NLO CT10, NNPDF2.3, HERAPDF1.5, and MSTW2008CPdeut PDF sets. The PDF uncertainty is at 68% C.L. The values are expressed as percentages.
Summary of the final results for muon charge asymmetry $\mathcal{A}$ with the muon $p_{T}>35$ GeV. The first uncertainty is statistical and the second is systematic. The theoretical predictions are obtained using the FEWZ 3.1 MC tool interfaced with the NLO CT10, NNPDF2.3, HERAPDF1.5, and MSTW2008CPdeut PDF sets. The PDF uncertainty is at 68% C.L. The values are expressed as percentages.
Covariance matrix (statistical and systematic uncertainties combined) with the muon $p_{T}>25$ GeV. The units are in $10^{-4}$.
We present a measurement of the muon charge asymmetry from the decay of the $W$ boson via W to mu nu using 7.3 fb^{-1} of integrated luminosity collected with the D0 detector at the Fermilab Tevatron Collider at sqrt{s} = 1.96 TeV. The muon charge asymmetry is presented in two kinematic regions in muon transverse momentum and event missing transverse energy: (p^{\mu}_{T} > 25 GeV, \met > 25 GeV) and (p^{\mu}_{T} > 35 GeV, \met > 35 GeV). The measured asymmetries are compared with theory predictions made using three parton distribution function sets. The predictions do not describe the data well for p^{\mu}_{T} > 35 GeV, \met > 35 GeV, and larger values of muon pseudorapidity.
Muon charge asymmetry for data and predictions from RESBOS+PHOTOS using the CTEQ6.6 PDFs. The measurement is shown with statistical uncertainties followed by systematic uncertainties. The uncertainties for the predictions are only from the PDFs.
Contributions from individual sources of systematic uncertainty for the ($p^{\mu}_{T} > 25$, $E_T^{missing} > 25$) GeV kinematic region. All uncertainty values are multiplied by 100. The columns (1-7) correspond to: 1.0 = Electro-Weak background 2.0 = Multi-Jet background 3.0 = Charge mis-identification 4.0 = Relative charge efficiency 5.0 = Magnet polarity weighting 6.0 = Momentum/$E_T^{missing}$ resolution 7.0 = Trigger isolation.
We present measurements of the forward-backward asymmetry in the angular distribution of leptons from decays of top quarks and antiquarks produced in proton-antiproton collisions. We consider the final state containing a lepton and at least three jets. The entire sample of data collected by the D0 experiment during Run II of the Fermilab Tevatron Collider, corresponding to 9.7 inverse fb of integrated luminosity, is used. The asymmetry measured for reconstructed leptons is $A_{FB}^l = \big(2.9 \pm 2.1(stat.) ^{+1.5}_{-1.7}(syst.) \big)$%. When corrected for efficiency and resolution effects within the lepton rapidity coverage of $|y_l|<1.5$, the asymmetry is found to be $A_{FB}^l = \big(4.2 \pm 2.3(stat.) ^{+1.7}_{-2.0}(syst.) \big)$%. Combination with the asymmetry measured in the dilepton final state yields $A_{FB}^l = \big(4.2 \pm 2.0(stat.) \pm 1.4(syst.) \big)$%. We examine the dependence of $A_{FB}^l$ on the transverse momentum and rapidity of the lepton. The results are in agreement with predictions from the next-to-leading-order QCD generator \mcatnlo, which predicts an asymmetry of $A_{FB}^l = 2.0$% for $|y_l|<1.5$.
Observed ASYMFB(LEPTON) as a function of PT(LEPTON) at reconstruction level.
Observed production-level ASYMFB(LEPTON) as a function of PT(LEPTON).
Observed production-level ASYMFB(LEPTON) as a function of ABS(YRAP(LEPTON)).
During 1993 and 1995 LEP was run at 3 energies near the Z$^0$peak in order to give improved measurements of the mass and width of the resonance. During 1994, LEP o
Cross section and forward-backward asymmetry in the E+ E- channel for the 1993 data. The polar angle is 44 to 136 degrees. Additional systematic error for cross section of 0.46 PCT (efficiencies and backgrounds) and 0.29 PCT (absolute luminosity). Additional systematic error for the asymmetry of 0.0026.
Cross section and forward-backward asymmetry in the E+ E- channel for the 1994 data. The polar angle is 44 to 136 degrees. Additional systematic error for cross section of 0.52 PCT (efficiencies and backgrounds) and 0.14 PCT (absolute luminosity). Additional systematic error for the asymmetry of 0.0021.
Cross section and forward-backward asymmetry in the E+ E- channel for the 1995 data. The polar angle is 44 to 136 degrees. Additional systematic error for cross section of 0.52 PCT (efficiencies and backgrounds) and 0.14 PCT (absolute luminosity). Additional systematic error for the asymmetry of 0.0020.
A charge asymmetry has been measured in hadron jets from e + e − annihilation at energies between 52 and 61.4 geV (〈√ s 〉=57.6 GeV). The measured asymmetry is A =11.4%±2.2%±2.1% and is consistent with the prediction of the standard model of the electroweak theory. By using the differential cross section, lower limits of the compositeness scale in eeqq contact interactions have been determined to be typically a few TeV at 95% CL.
Data are fully corrected for detector effects, resolution and radiative effects.
The reaction e+e−→μ+μ− has been measured at s=57.77GeV, based on 289.6±2.6 pb−1 data collected with the VENUS detector at TRISTAN. The production cross section is measured in bins of the production angle within an angular acceptance of |cosθ|<~0.75, according to a model-independent definition. The result is consistent with the prediction of the standard electroweak theory. Although a trend in measurements at lower energies that the total cross section tends to be smaller than the prediction remains, the discrepancy is not significant. The model-independent result is converted to the differential cross section in the effective-Born scheme by unfolding photon-radiation effects. This result can be extrapolated to quantities for the full solid angle as σtotEB=30.05±0.59 pb and AFBEB=−0.350±0.017, by imposing an ordinary assumption on the production-angle dependence. The converted results are used to set constraints on extensions of the standard theory. S-matrix parametrization, and possible contributions from contact interactions and heavy neutral-scalar exchanges are examined.
Total cross section and forward backward asymmetry results in the effective-Born scheme.
Using 123 multihadronic inclusive muon-production e+e− annihilation events at an average c.m. energy of 55.2 GeV, we extracted the forward-backward charge asymmetry of the e+e−→bb¯ process and the R ratio for bb¯ production. We used an analysis method in which the behavior of the c quark and lighter quarks is assumed, with only that of the b quark left indeterminate. The results, Ab=-0.72±0.28(stat)±0.13(syst) and Rb=0.57±0.16±0.10, are consistent with the standard model.
Asymmetry in BOTTOM quark production.
We present final measurements of the Z boson-lepton coupling asymmetry parameters Ae, Amu, and Atau with the complete sample of polarized Z bosons collected by the SLD detector at the SLAC Linear Collider. From the left-right production and decay polar angle asymmetries in leptonic Z decays we measure Ae = 0.1544 +- 0.0060, Amu = 0.142 +- 0.015, and Atau = 0.136 +- 0.015. Combined with our left-right asymmetry measured from hadronic decays, we find Ae = 0.1516 +- 0.0021. Assuming lepton universality, we obtain a combined effective weak mixing angle of sin**2 theta^{eff}_W = 0.23098 +- 0.00026.
No description provided.
We measure forward cross sections for production of D+, D0, Ds, D*+, and Λc in collisions of π±, K±, and p on a nuclear target. Production induced by different beam particles is found to be the same within statistics. Strange and baryonic final states are seen to contribute appreciably to the total charm cross section, which our measurements indicate is larger than but consistent with QCD predictions. The energy dependence mapped out by these and previous measurements is consistent with theory. Leading-particle asymmetry measurements for K and p-induced charm production are also presented.
Leading particle asymmetries defined as (SIG(LEADING)- SIG(NONLEADING))/(SIG(LEADING)+SIG(NONLEADING)).
The production of $D_s^-$ relative to $D_s^+$ as a function of $x_F $ with 600 GeV/c $\Sigma^-$ beam is measured in the interval $0.15 < x_F < 0.7$ by the SELEX (E781) experiment at Fermilab. The integrated charge asymmetries with 600 GeV/c $\Sigma^-$ beam ($0.53\pm0.06$) and $\pi^-$ beam ($0.06\pm0.11$) are also compared. The results show the $\Sigma^-$ beam fragments play a role in the production of $D_s^-$, as suggested by the leading quark model.
Production asymmetry for the SIGMA- beam.
Integrated asymmetry (with XL > 0.15) for the PI- and SIGMA- beams.
Forum