The proton spin structure is not understood yet and there has remained large uncertainty on Delta g, the gluon spin contribution to the proton. Double helicity asymmetry (A_LL) of pi0 production in polarized pp collisions is used to constrain Delta g. In this report, preliminary results of A_LL of pi0 in pp collisions at sqrt(s) = 62.4 GeV measured by PHENIX experiment in 2006 is presented. It can probe higer x region than the previously reported pi0 A_LL at sqrt(s) = 200 GeV thanks to the lower center of mass energy.
Inclusive cross section and double helicity asymmetry for π^0 production in p+p collisions at sqrt(s)=200 GeV: Implications for the polarized gluon distribution in the proton
Helicity-dependent parton distribution functions at next-to-next-to-leading order accuracy from inclusive and semi-inclusive deep-inelastic scattering data
The gluon spin contribution to the proton spin from the double helicity asymmetry in inclusive pi^0 production in polarized p+p collisions at sqrt(s)=200 GeV
Transverse momentum dependence of the quark helicity distributions and the Cahn effect in double-spin asymmetry $A_{LL}$ in Semi Inclusive DIS
在半包含深度非弹性散射的LO QCD部分子模型$\ell N \to \ell h X$中，利用未积分的夸克分布和碎裂函数，研究了双夸克自旋不对称性$A_{LL}$对$\bfP_{hT}$的依赖性.我们包括1/Q的运动学修正，诱导方位调制的不对称性，类似于在非极化SIDIS的卡恩效应。我们表明，$A_{LL}$和加权DSA $A_{LL}^{\cosϕ_h}$的研究允许提取的横向动量依赖的未积分螺旋度分布函数$g_{1L}^q(x,k_\perp)$ [或$Δq(x, k_\perp)]$。预测，基于一些模型的未知功能，给出了正在进行的COMPASS，HERMES和JLab实验。
Measurement of the parity-violating asymmetry parameter alpha_b and the helicity amplitudes for the decay Lambda_b->J/psi+Lambda with the ATLAS detector
Longitudinal double-spin asymmetry and cross section for inclusive neutral pion production at midrapidity in polarized proton collisions at sqrt(s) = 200 GeV
The differential cross section and charge asymmetry for inclusive pp to W + X to mu + neutrino + X production at sqrt(s) = 8 TeV are measured as a function of muon pseudorapidity. The data sample corresponds to an integrated luminosity of 18.8 inverse femtobarns recorded with the CMS detector at the LHC. These results provide important constraints on the parton distribution functions of the proton in the range of the Bjorken scaling variable x from 10E-3 to 10E-1.
Measurement of the cross-section and forward-backward charge asymmetry for the b and c-quark in e+e- annihilation with inclusive muons at sqrt(s) = 58 GeV
Measurements of the muon charge asymmetry in inclusive $pp \rightarrow WX$ production at $\sqrt{s}=7$ TeV are presented. The data sample corresponds to an integrated luminosity of 4.7 $\mathrm{fb^{-1}}$ recorded with the CMS detector at the LHC. With a sample of more than twenty million $W \rightarrow μν$ 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 $10^{-3}$ to $10^{-1}$. These measurements ar…
This paper presents combinations of inclusive and differential measurements of the charge asymmetry ($A_{\mathrm{C}}$) in top quark pair ($\mathrm{t}\overline{\mathrm{t}}$) events with a lepton+jets signature by the ATLAS and CMS Collaborations, using data from LHC proton-proton collisions at centre-of-mass energies of 7 and 8 TeV corresponding to integrated luminosities of about 5 and 20 fb$^{-1}$ for each experiment, respectively. The resulting combined LHC measurements of the inclusive charge asymmetry are $A_{\mathrm{C}}^{\mathrm{LHC7}} = 0.005 \pm0.007 \text{ (stat)}\pm0.006 \text{ (syst)…
Measurement of the muon charge asymmetry in inclusive pp to WX production at sqrt(s) = 7 TeV and an improved determination of light parton distribution functions
PHENIX measurements are presented for the cross-section and double-helicity asymmetry ($A_{LL}$) of inclusive $π^{0}$ production ($A_{LL}^{π^{0}}$) at midrapidity from $p+p$ collisions at $\sqrt{s}=510$ GeV from data taken in 2012 and 2013 at the Relativistic Heavy Ion Collider (RHIC). The next-to-leading order (NLO) perturbative QCD (pQCD) calculation agrees excellently with the presented cross-section result. The $A_{LL}^{π^{0}}$ follows an increasingly positive asymmetry as functions of $p_{T}$ and $\sqrt{s}$ at the fixed $x_{T}$. The latest global analysis results, which support the positi…
The CDF and D0 experiments at the Fermilab Tevatron have measured the asymmetry between yields of forward- and backward-produced top and antitop quarks based on their rapidity difference and the asymmetry between their decay leptons. These measurements use the full data sets collected in proton-antiproton collisions at a center-of-mass energy of $\sqrt s =1.96$ TeV. We report the results of combinations of the inclusive asymmetries and their differential dependencies on relevant kinematic quantities. The combined inclusive asymmetry is $A_{\mathrm{FB}}^{t\bar{t}} = 0.128 \pm 0.025$. The combin…
The t t-bar charge asymmetry is measured in proton-proton collisions at a centre-of-mass energy of 8 TeV. The data, collected with the CMS experiment at the LHC, correspond to an integrated luminosity of 19.7 inverse femtobarns. Selected events contain an electron or a muon and four or more jets, where at least one jet is identified as originating from b-quark hadronization. The inclusive charge asymmetry is found to be 0.0010 +/- 0.0068 (stat) +/- 0.0037 (syst). In addition, differential charge asymmetries as a function of rapidity, transverse momentum, and invariant mass of the t t-bar syste…
The differential cross section and charge asymmetry for inclusive W boson production at $\sqrt{s} =$ 13 TeV is measured for the two transverse polarization states as a function of the W boson absolute rapidity. The measurement uses events in which a W boson decays to a neutrino and either a muon or an electron. The data sample of proton-proton collisions recorded with the CMS detector at the LHC in 2016 corresponds to an integrated luminosity of 35.9 fb$^{-1}$. The differential cross section and its value normalized to the total inclusive W boson production cross section are measured over the …
Single spin asymmetry measurements for $π^0$ inclusive productions in $p+p_{\uparrow} \to π^0 + X$ and $π^-+\p_{\uparrow}\to π^0+X$ reactions at 70 and 40 GeV respectively
Longitudinally polarized $p+p$ scattering experiments provide access to gluon polarization via measurement of the double helicity asymmetry, $A_{LL}$. At the completion of the 2013 RHIC running period, a significant dataset of $π^{0}$s corresponding to an integrated luminosity of 46 $\text{pb}^{-1}$ (2012) and 8 $\text{pb}^{-1}$ (2013) produced from polarized $p+p$ scattering at $\sqrt{s}=510$ GeV with an average beam polarization of approximately $50\%$ was acquired. The $π^{0}$ kinematics were measured via isolation cones by the STAR Forward Meson Spectrometer, an electromagnetic calorimeter…
We study the semi-inclusive production of real, high-$p_T$, isolated photons in unpolarized and polarized lepton-proton collisions, $\ell p\to \ellγX$. In particular we analyze the transverse nucleon single-spin asymmetry within the collinear twist-3 formalism in perturbative QCD to leading order (LO) accuracy. We find that this spin asymmetry is generated by twist-3 dynamical quark-gluon-quark ($qgq$) correlations in the nucleon through the so-called soft-fermion and hard pole contributions. Hence, this process unprecedentedly allows for a point-by-point scan of the support of the dynamical $…
