Polarized proton-proton collisions provide leading-order access to gluons, presenting an opportunity to constrain gluon spin-momentum correlations within transversely polarized protons and enhance our understanding of the three-dimensional structure of the proton. Midrapidity open-heavy-flavor production at $\sqrt{s}=200$ GeV is dominated by gluon-gluon fusion, providing heightened sensitivity to gluon dynamics relative to other production channels. Transverse single-spin asymmetries of positrons and electrons from heavy-flavor hadron decays are measured at midrapidity using the PHENIX detector at the Relativistic Heavy Ion Collider. These charge-separated measurements are sensitive to gluon correlators that can in principle be related to gluon orbital angular momentum via model calculations. Explicit constraints on gluon correlators are extracted for two separate models, one of which had not been constrained previously.
Data from Figure 1 of open heavy flavor $e^{\pm}$ transverse single-spin asymmetries in transversely polarized p+p collisions as a function of $p_{T}$.
Presented are the first measurements of the transverse single-spin asymmetries ($A_N$) for neutral pions and eta mesons in $p$+Au and $p$+Al collisions at $\sqrt{s_{_{NN}}}=200$ GeV in the pseudorapidity range $|\eta|<$0.35 with the PHENIX detector at the Relativistic Heavy Ion Collider. The asymmetries are consistent with zero, similar to those for midrapidity neutral pions and eta mesons produced in $p$+$p$ collisions. These measurements show no evidence of additional effects that could potentially arise from the more complex partonic environment present in proton-nucleus collisions.
Data from Figure 2 (a) of the $\pi^{0}$ transverse single-spin asymmetry in $\sqrt{s_{NN}}=200$ GeV $p^{\uparrow}+$Au and $p^{\uparrow}+$Al collisions as a function of $p_{T}$.
Data from Figure 2 (b) of the $\eta$ transverse single-spin asymmetry in $\sqrt{s_{NN}}=200$ GeV $p^{\uparrow}+$Au and $p^{\uparrow}+$Al collisions as a function of $p_{T}$.
DATA FOR EVENTS WITHOUT PARTICLES WITH PT > .8 GEV.
DATA FOR EVENTS WITH ONE PARTICLE WITH PT > .8 GEV.
DATA FOR EVENTS WITH TWO OR MORE PARTICLES WITH PT > .8 GEV.
The inclusive $D_s^{\pm}$ production asymmetry is measured in $pp$ collisions collected by the LHCb experiment at centre-of-mass energies of $\sqrt{s} =7$ and 8 TeV. Promptly produced $D_s^{\pm}$ mesons are used, which decay as $D_s^{\pm}\to\phi\pi^{\pm}$, with $\phi\to K^+K^-$. The measurement is performed in bins of transverse momentum, $p_{\rm T}$, and rapidity, $y$, covering the range $2.5
Values of the $D_s^+$ production asymmetry in percent, including, respectively, the statistical and systematic uncertainties for each of the $D_s^+$ kinematic bins using the combined $\sqrt{s} =7$ and 8 TeV data sets. The statistical and systematic uncertainties include the corresponding contributions from the detection asymmetries, and are therefore correlated between the bins. ASYM is defined as ASYM = ((SIG(D/S+)-SIG(D/S-))/(SIG(D/S+)+SIG(D/S+)).
Values of the $D_s^+$ production asymmetry in percent, including, respectively, the statistical and systematic uncertainties for each of the $D_s^+$ kinematic bins using the $\sqrt{s} =7$ TeV data set. The statistical and systematic uncertainties include the corresponding contributions from the detection asymmetries, and are therefore correlated between the bins. ASYM is defined as ASYM = ((SIG(D/S+)-SIG(D/S-))/(SIG(D/S+)+SIG(D/S+)).
Values of the $D_s^+$ production asymmetry in percent, including, respectively, the statistical and systematic uncertainties for each of the $D_s^+$ kinematic bins using the $\sqrt{s} =8$ TeV data set. The statistical and systematic uncertainties include the corresponding contributions from the detection asymmetries, and are therefore correlated between the bins. ASYM is defined as ASYM = ((SIG(D/S+)-SIG(D/S-))/(SIG(D/S+)+SIG(D/S+)).
The charged particle transverse momentum spectra in the midrapidity and forward pseudorapidity ranges are presented for pPb collisions at $\sqrt{s_{\rm NN}}=5.02$~TeV. The data sample corresponding to an integrated luminosity of 26~${\rm nb}^{-1}$ was collected with the CMS detector at the LHC. The nuclear modification factor is measured at midrapidity by normalizing the measured pPb spectrum to a pp reference spectrum constructed from previous measurements. In addition, the asymmetries in the charged particle yields between equivalent positive and negative pseudorapidity ranges in the center-of-mass frame are presented as a function of transverse momentum.
Charged-particle forward-backward yield asymmetry.
Charged-particle forward-backward yield asymmetry.
Charged-particle forward-backward yield asymmetry.
The production of Z bosons in pPb collisions at sqrt(s[NN]) = 5.02 TeV is studied by the CMS experiment via the electron and muon decay channels. The inclusive cross section is compared to pp collision predictions, and found to scale with the number of elementary nucleon-nucleon collisions. The differential cross sections as a function of the Z boson rapidity and transverse momentum are measured. Though they are found to be consistent within uncertainty with theoretical predictions both with and without nuclear effects, the forward-backward asymmetry suggests the presence of nuclear effects at large rapidities. These results provide new data for constraining nuclear parton distribution functions.
Forward-backward asymmetry (AFB) distribution of the Z bosons in pPb collisions as a function of rapidity in the fiducial region for the combined leptonic decay channel.
We present asymmetries between the production of D+ and D- mesons in Fermilab experiment E791 as a function of xF and pt**2. The data used here consist of 74,000 fully-reconstructed charmed mesons produced by a 500 GeV/c pi- beam on C and Pt foils. The measurements are compared to results of models which predict differences between the production of heavy-quark mesons that have a light quark in common with the beam (leading particles) and those that do not (non-leading particles). While the default models do not agree with our data, we can reach agreement with one of them, PYTHIA, by making a limited number of changes to parameters used.
Asymmetry parameter A = (SIG(D-)-SIG(D+))/(SIG(D+)+SIG(D-)) have been studied as function of Feynman variable X. 'Nucleus' are PT and C.
Asymmetry parameter A = (SIG(D-)-SIG(D+))/(SIG(D+)+SIG(D-)) have been studied as function of PT**2. 'Nucleus' are PT and C.
Asymmetry parameter A = (SIG(D-)-SIG(D+))/(SIG(D+)+SIG(D-)) have been studied as function of PT**2. 'Nucleus' are PT and C.
This paper presents measurements of the production of Ds- mesons relative to Ds+ mesons as functions of x_F and square of p_t for a sample of 2445 Ds decays to phi pi. The Ds mesons were produced in Fermilab experiment E791 with 500 GeV/c pi- mesons incident on one platinum and four carbon foil targets. The acceptance-corrected integrated asymmetry in the x_F range -0.1 to 0.5 for Ds+- mesons is 0.032 +- 0.022 +- 0.022, consistent with no net asymmetry. The results, as functions of x_F and square of p_t, are compared to predictions and to the large production asymmetry observed for D+- mesons in the same experiment. These comparisons support the hypothesis that production asymmetries come from the fragmentation process and not from the charm quark production itself.
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The forward-backward charge asymmetry for the process e + e − → b b ̄ → μ ± + hadrons has been measured using the JADE detector at PETRA. An asymmetry of (−22.8 ± 6.0 ± 2.5)% was observed at an average center of mass energy of 34.6 GeV. For comparison, an asymmetry of −25.2% is expected on the basis of the standard Glashow-Salam-Weinberg model.
THE VALUE OF CONST HAVE BEEN RESCALED TO DEFINITION I3(Q) = 1/2 BY OPY.
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