Longitudinal Double-Spin Asymmetries for Dijet Production at Intermediate Pseudorapidity in Polarized $pp$ Collisions at $\sqrt{s}$ = 200 GeV

The STAR collaboration Adam, Jaroslav ; Adamczyk, Leszek ; Adams, Joseph ; et al.
Phys.Rev.D 98 (2018) 032011, 2018.
Inspire Record 1674714 DOI 10.17182/hepdata.130944

We present the first measurements of the longitudinal double-spin asymmetry $A_{LL}$ for dijets with at least one jet reconstructed within the pseudorapidity range $0.8 < \eta < 1.8$. The dijets were measured in polarized $pp$ collisions at a center-of-mass energy $\sqrt{s}$ = 200 GeV. Values for $A_{LL}$ are determined for several distinct event topologies, defined by the jet pseudorapidities, and span a range of parton momentum fraction $x$ down to $x \sim$ 0.01. The measured asymmetries are found to be consistent with the predictions of global analyses that incorporate the results of previous RHIC measurements. They will provide new constraints on $\Delta g(x)$ in this poorly constrained region when included in future global analyses.

3 data tables match query

$A_{LL}$ as a function of parton-level invariant mass for dijets with the East barrel-endcap.

$A_{LL}$ as a function of parton-level invariant mass for dijets with the West barrel-endcap.

$A_{LL}$ as a function of parton-level invariant mass for dijets with the endcap-endcap.


Collins and Sivers asymmetries for pions and kaons in muon-deuteron DIS

The COMPASS collaboration Alekseev, M. ; Alexakhin, V.Yu. ; Alexandrov, Yu. ; et al.
Phys.Lett.B 673 (2009) 127-135, 2009.
Inspire Record 779473 DOI 10.17182/hepdata.48532

The measurements of the Collins and Sivers asymmetries of identified hadrons produced in deep-inelastic scattering of 160 GeV/c muons on a transversely polarised 6LiD target at COMPASS are presented. The results for charged pions and charged and neutral kaons correspond to all data available, which were collected from 2002 to 2004. For all final state particles both the Collins and Sivers asymmetries turn out to be small, compatible with zero within the statistical errors, in line with the previously published results for not identified charged hadrons, and with the expected cancellation between the u- and d-quark contributions.

30 data tables match query

The Collins and Sivers asymmetry as a function of X for 'ALL' positive pions from the 2003-2004 data.. Errors are statistical only.

The Collins and Sivers asymmetry as a function of PT for 'ALL' positive pions from the 2003-2004 data.. Errors are statistical only.

The Collins and Sivers asymmetry as a function of Z for 'ALL' positive pions from the 2003-2004 data.. Errors are statistical only.

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Observation of Transverse Spin-Dependent Azimuthal Correlations of Charged Pion Pairs in $p^\uparrow+p$ at $\sqrt{s}=200$ GeV

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.Lett. 115 (2015) 242501, 2015.
Inspire Record 1357596 DOI 10.17182/hepdata.73282

We report the observation of transverse polarization-dependent azimuthal correlations in charged pion pair production with the STAR experiment in $p^\uparrow+p$ collisions at RHIC. These correlations directly probe quark transversity distributions. We measure signals in excess of five standard deviations at high transverse momenta, at high pseudorapidities eta>0.5, and for pair masses around the mass of the rho-meson. This is the first direct transversity measurement in p+p collisions. Comparing the results to data from lepton-nucleon scattering will test the universality of these spin-dependent quantities.

15 data tables match query

$p_T$ asymmetries, $\eta$ < 0, maximum opening angle of 0.2.

$<M_{inv}>$ asymmetries, $\eta$ < 0, maximum opening angle of 0.2.

$p_T$ asymmetries, $\eta$ > 0, maximum opening angle 0.2.

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Experimental investigation of transverse spin asymmetries in muon-p SIDIS processes: Sivers asymmetries

The COMPASS collaboration Adolph, C. ; Alekseev, M.G. ; Alexakhin, V.Yu. ; et al.
Phys.Lett.B 717 (2012) 383-389, 2012.
Inspire Record 1115721 DOI 10.17182/hepdata.59737

The COMPASS Collaboration at CERN has measured the transverse spin azimuthal asymmetry of charged hadrons produced in semi-inclusive deep inelastic scattering using a 160 GeV positive muon beam and a transversely polarised NH_3 target. The Sivers asymmetry of the proton has been extracted in the Bjorken x range 0.003<x<0.7. The new measurements have small statistical and systematic uncertainties of a few percent and confirm with considerably better accuracy the previous COMPASS measurement. The Sivers asymmetry is found to be compatible with zero for negative hadrons and positive for positive hadrons, a clear indication of a spin-orbit coupling of quarks in a transversely polarised proton. As compared to measurements at lower energy, a smaller Sivers asymmetry for positive hadrons is found in the region x > 0.03. The asymmetry is different from zero and positive also in the low x region, where sea-quarks dominate. The kinematic dependence of the asymmetry has also been investigated and results are given for various intervals of hadron and virtual photon fractional energy. In contrast to the case of the Collins asymmetry, the results on the Sivers asymmetry suggest a strong dependence on the four-momentum transfer to the nucleon, in agreement with the most recent calculations.

54 data tables match query

The Sivers asymmetry, from the 2010 data set, for positive hadrons as a function of X for full range. Also shown are the mean values of other variables plus the correlation with the Collins data measurments.

The Sivers asymmetry, from the 2010 data set, for negative hadrons as a function of X for full range. Also shown are the mean values of other variables plus the correlation with the Collins data measurments.

The Sivers asymmetry, from the 2010 data set, for positive hadrons as a function of PT for full range. Also shown are the mean values of other variables plus the correlation with the Collins data measurments.

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Experimental investigation of transverse spin asymmetries in muon-p SIDIS processes: Collins asymmetries

The COMPASS collaboration Adolph, C. ; Alekseev, M.G. ; Alexakhin, V.Yu. ; et al.
Phys.Lett.B 717 (2012) 376-382, 2012.
Inspire Record 1115720 DOI 10.17182/hepdata.59732

The COMPASS Collaboration at CERN has measured the transverse spin azimuthal asymmetry of charged hadrons produced in semi-inclusive deep inelastic scattering using a 160 GeV positive muon beam and a transversely polarised NH_3 target. The Collins asymmetry of the proton was extracted in the Bjorken x range 0.003<x<0.7. These new measurements confirm with higher accuracy previous measurements from the COMPASS and HERMES collaborations, which exhibit a definite effect in the valence quark region. The asymmetries for negative and positive hadrons are similar in magnitude and opposite in sign. They are compatible with model calculations in which the u-quark transversity is opposite in sign and somewhat larger than the d-quark transversity distribution function. The asymmetry is extracted as a function of Bjorken $x$, the relative hadron energy $z$ and the hadron transverse momentum p_T^h. The high statistics and quality of the data also allow for more detailed investigations of the dependence on the kinematic variables. These studies confirm the leading-twist nature of the Collins asymmetry.

54 data tables match query

The Collins asymmetry, from the 2010 data set, for positive hadrons as a function of X for full range. Also shown are the mean values of other variables plus the correlation with the Sivers data measurments.

The Collins asymmetry, from the 2010 data set, for negative hadrons as a function of X for full range. Also shown are the mean values of other variables plus the correlation with the Sivers data measurments.

The Collins asymmetry, from the 2010 data set, for positive hadrons as a function of PT for full range. Also shown are the mean values of other variables plus the correlation with the Sivers data measurments.

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Transverse target spin asymmetries in exclusive $\rho^0$ muoproduction

The COMPASS collaboration Adolph, C ; Alekseev, M G ; Alexakhin, V Yu ; et al.
Phys.Lett.B 731 (2014) 19-26, 2014.
Inspire Record 1257385 DOI 10.17182/hepdata.66743

Exclusive production of $\rho^0$ mesons was studied at the COMPASS experiment by scattering 160 GeV/$c$ muons off transversely polarised protons. Five single-spin and three double-spin azimuthal asymmetries were measured as a function of $Q^2$, $x_{Bj}$, or $p_{T}^{2}$. The $\sin \phi_S$ asymmetry is found to be $-0.019 \pm 0.008(stat.) \pm 0.003(syst.)$. All other asymmetries are also found to be of small magnitude and consistent with zero within experimental uncertainties. Very recent calculations using a GPD-based model agree well with the present results. The data is interpreted as evidence for the existence of chiral-odd, transverse generalized parton distributions.

6 data tables match query

Single-spin azimuthal asymmetries for a transversely (T) polarised target and unpolarised (U) beam.

Single-spin azimuthal asymmetries for a transversely (T) polarised target and unpolarised (U) beam.

Single-spin azimuthal asymmetries for a transversely (T) polarised target and unpolarised (U) beam.

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Version 2
Measurement of azimuthal hadron asymmetries in semi-inclusive deep inelastic scattering off unpolarised nucleons

The COMPASS collaboration Adolph, C. ; Akhunzyanov, R. ; Alekseev, M.G. ; et al.
Nucl.Phys.B 886 (2014) 1046-1077, 2014.
Inspire Record 1278730 DOI 10.17182/hepdata.64754

Spin-averaged asymmetries in the azimuthal distributions of positive and negative hadrons produced in deep inelastic scattering were measured using the CERN SPS muon beam at $160$ GeV/c and a $^6$LiD target. The amplitudes of the three azimuthal modulations $\cos\phi_h$, $\cos2\phi_h$ and $\sin\phi_h$ were obtained binning the data separately in each of the relevant kinematic variables $x$, $z$ or $p_T^{\,h}$ and binning in a three-dimensional grid of these three variables. The amplitudes of the $\cos \phi_h$ and $\cos 2\phi_h$ modulations show strong kinematic dependencies both for positive and negative hadrons.

17 data tables match query

ASYMUU(SIN(PHI(HADRON))) asymmetries for positive and negative hadrons as a function of XB. The errors are statistical and systematic.

ASYMUU(SIN(PHI(HADRON))) asymmetries for positive and negative hadrons as a function of Z. The errors are statistical and systematic.

ASYMUU(SIN(PHI(HADRON))) asymmetries for positive and negative hadrons as a function of PT(HADRON). The errors are statistical and systematic.

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Measurement of the forward backward asymmetry of c and b quarks at the Z pole using reconstructed D mesons.

The DELPHI collaboration Abreu, P. ; Adye, T. ; Adzic, P. ; et al.
Eur.Phys.J.C 10 (1999) 219-237, 1999.
Inspire Record 495464 DOI 10.17182/hepdata.49295

A measurement of the forward--backward asymmetry of $e^{+}e^{-} \to c\bar{c}$ and $e^{+}e^{-} \to b\bar{b}$ on the $Z$ resonance is performed using about 3.5 million hadronic $Z$ decays collected by the DELPHI detector at LEP in the years 1992 to 1995. The heavy quark is tagged by the exclusive reconstruction of several $D$ meson decay modes. The forward--backward asymmetries for $c$ and $b$ quarks at the $Z$ resonance are determined to be: \[ \renewcommand{\arraystretch}{1.6} \begin{array}{rcr@{}l} \Afbc(\sqrt{s} = 91.235 {\rm GeV}) &=& &0.0659 \pm 0.0094 (stat) \pm 0.0035 (syst) \Afbb (\sqrt{s} = 91.235 {\rm GeV}) &=& &0.0762 \pm 0.0194 (stat) \pm 0.0085 (syst) \Afbc(\sqrt{s} = 89.434 {\rm GeV}) &=&-&0.0496 \pm 0.0368 (stat) \pm 0.0053 (syst) \Afbb(\sqrt{s} = 89.434 {\rm GeV}) &=& &0.0567 \pm 0.0756 (stat) \pm 0.0117 (syst) \Afbc(\sqrt{s} = 92.990 {\rm GeV}) &=& &0.1180 \pm 0.0318 (stat) \pm 0.0062 (syst) \Afbb(\sqrt{s} = 92.990 {\rm GeV}) &=& &0.0882 \pm 0.0633 (stat) \pm 0.0122 (syst) \end{array} \] The combination of these results leads to an effective electroweak mixing angle of: SINEFF = 0.2332 \pm 0.0016

1 data table match query

No description provided.


Separated cross sections in \pi^0 electroproduction at threshold at Q^2 = 0.05 GeV^2/c^2

The A1 collaboration Weis, M. ; Bartsch, P. ; Baumann, D. ; et al.
Eur.Phys.J.A 38 (2008) 27-33, 2008.
Inspire Record 751930 DOI 10.17182/hepdata.51606

The differential cross sections \sigma_0=\sigma_T+\epsilon \sigma_L, \sigma_{LT}, and \sigma_{TT} of \pi^0 electroproduction from the proton were measured from threshold up to an additional center of mass energy of 40 MeV, at a value of the photon four-momentum transfer of Q^2= 0.05 GeV^2/c^2 and a center of mass angle of \theta=90^\circ. By an additional out-of-plane measurement with polarized electrons \sigma_{LT'} was determined. This showed for the first time the cusp effect above the \pi^+ threshold in the imaginary part of the s-wave. The predictions of Heavy Baryon Chiral Perturbation Theory are in disagreement with these data. On the other hand, the data are somewhat better predicted by the MAID phenomenological model and are in good agreement with the dynamical model DMT.

1 data table match query

Beam helicity asymmetry.


Asymmetries in the production of Lambda/c+ and Lambda/c- baryons in 500-GeV/c pi- nucleon interactions.

The E791 collaboration Aitala, E.M ; Amato, S ; Anjos, J.C ; et al.
Phys.Lett.B 495 (2000) 42-48, 2000.
Inspire Record 531814 DOI 10.17182/hepdata.50150

We present a measurement of asymmetries in the production of $\Lambda_c^+$ and $\Lambda_c^-$ baryons in 500 GeV/c $\pi^-$--nucleon interactions from the E791 experiment at Fermilab. The asymmetries were measured as functions of Feynman x ($x_F$) and transverse momentum squared ($p_T^2$) using a sample of $1819 \pm 62$ $\Lambda_c$'s observed in the decay channel $\Lambda_c \to pK^-\pi^+$. We observe more $\Lambda_c^+$ than $\Lambda_c^-$ baryons, with an asymmetry of $(12.7\pm3.4\pm1.3) %$ independent of $x_F$ and $p_T^2$ in our kinematical range $(-0.1 < x_F < 0.6$ and $0.0 < p_T^2 < 8.0 (GeV/c)^2$). This $\Lambda_c$ asymmetry measurement is the first with data in both the positive and negative $x_F$ regions.

2 data tables match query

No description provided.

No description provided.


Measurement of the Lepton Forward-Backward Asymmetry in Inclusive $B \rightarrow X_s \ell^+ \ell^-$ Decays

The Belle collaboration Sato, Y. ; Ishikawa, A. ; Yamamoto, H. ; et al.
Phys.Rev.D 93 (2016) 032008, 2016.
Inspire Record 1283183 DOI 10.17182/hepdata.64698

We report the first measurement of the lepton forward-backward asymmetry ${\cal A}_{\rm FB}$ as a function of the squared four-momentum of the dilepton system, $q^2$, for the electroweak penguin process $B \rightarrow X_s \ell^+ \ell^-$ with a sum of exclusive final states, where $\ell$ is an electron or a muon and $X_s$ is a hadronic recoil system with an $s$ quark. The results are based on a data sample containing $772\times10^6$ $B\bar{B}$ pairs recorded at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB $e^+ e^-$ collider. ${\cal A}_{\rm FB}$ for the inclusive $B \rightarrow X_s \ell^+ \ell^-$ is extrapolated from the sum of 10 exclusive $X_s$ states whose invariant mass is less than 2 GeV/$c^2$. For $q^2 > 10.2$ GeV$^2$/$c^2$, ${\cal A}_{\rm FB} < 0$ is excluded at the 2.3$\sigma$ level, where $\sigma$ is the standard deviation. For $q^2 < 4.3$ GeV$^2$/$c^2$, the result is within 1.8$\sigma$ of the Standard Model theoretical expectation.

1 data table match query

The value of ASYM(FB) obtained from the fit in each of the four Q**2 bins.


Forward - backward charge asymmetry of quark pairs produced at the KEK TRISTAN e+ e- collider

The AMY collaboration Stuart, D. ; Breedon, R.E. ; Chinitz, L.M. ; et al.
Phys.Rev.D 49 (1994) 3098-3105, 1994.
Inspire Record 378569 DOI 10.17182/hepdata.22552

We report on a measurement of the forward-backward charge asymmetry in e+e−→qq¯ at KEK TRISTAN, where the asymmetry is near maximum. We sum over all flavors and measure the asymmetry by determining the charge of the quark jets. In addition we exploit flavor dependencies in the jet charge determination to enhance the contributions of certain flavors. This provides a check on the asymmetries of individual flavors. The measurement agrees with the standard model expectations.

1 data table match query

Forward--backward asymmetry summed over all flavours of quarks.


Spin asymmetries from O-16(gamma(pol.),p pi-) near Delta resonance energies

Hicks, K. ; Baghaei, H. ; Caracappa, A. ; et al.
Phys.Rev.C 55 (1997) R12-R15, 1997.
Inspire Record 456890 DOI 10.17182/hepdata.25766

Spin asymmetries for the 16O(γ→,pπ−) reaction are reported for incident photon energies of 293 ± 20 MeV, proton angles ranging from 28° to 140° (lab), and pion angles of 35° to 115°. The data are compared with calculations in a quasifree plane-wave impulse approximation model. This model is in good agreement with the data at small momentum transfer q, but does not follow the trend of the data at large q. Sensitivity to the Δ-nucleus potential and to modification of the Δ lifetime from nuclear medium effects are explored using a simple modification of the Δ propagator in the calculations.

6 data tables match query

The data are extracted from the figures by S.Slabospitsky. ASYM is the spin asymmetry. It is the ratio of the difference to the sum of the cross sections with the photon's linear polarization oriented parallel or perpendicular to the scattering plane.

The data are extracted from the figures by S.Slabospitsky. ASYM is the spin asymmetry. It is the ratio of the difference to the sum of the cross sections with the photon's linear polarization oriented parallel or perpendicular to the scattering plane.

The data are extracted from the figures by S.Slabospitsky. ASYM is the spin asymmetry. It is the ratio of the difference to the sum of the cross sections with the photon's linear polarization oriented parallel or perpendicular to the scattering plane.

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A Measurement of the $e^+ e^- \to b \bar{b}$ Forward - Backward Charge Asymmetry at $\sqrt{s}=29$-{GeV}

The MAC collaboration Band, H.R. ; Camporesi, T. ; Chadwick, G.B. ; et al.
Phys.Lett.B 218 (1989) 369-373, 1989.
Inspire Record 276692 DOI 10.17182/hepdata.29845

High p ⊥ inclusive muon events produced in e + e − annihilations at √ s =29 GeV have been analyzed to obtain a measurement of the b b forward-backward charge asymmetry. The result A b =0.034±0.070±0.035 differs from the theoretical expectation (−0.16) unless substantial B 0  B 0 mixing is assumed.

1 data table match query

No description provided.


Measurement of Parity-Violating Asymmetry in Electron-Deuteron Inelastic Scattering

Wang, D. ; Pan, K. ; Subedi, R. ; et al.
Phys.Rev.C 91 (2015) 045506, 2015.
Inspire Record 1327482 DOI 10.17182/hepdata.72848

The parity-violating asymmetries between a longitudinally-polarized electron beam and an unpolarized deuterium target have been measured recently. The measurement covered two kinematic points in the deep inelastic scattering region and five in the nucleon resonance region. We provide here details of the experimental setup, data analysis, and results on all asymmetry measurements including parity-violating electron asymmetries and those of inclusive pion production and beam-normal asymmetries. The parity-violating deep-inelastic asymmetries were used to extract the electron-quark weak effective couplings, and the resonance asymmetries provided the first evidence for quark-hadron duality in electroweak observables. These electron asymmetries and their interpretation were published earlier, but are presented here in more detail.

5 data tables match query

Asymmetry results on $\vec e-^2$H parity-violating scattering from the PVDIS experiment at JLab.

Asymmetry results on $\vec e-^2$H parity-violating scattering from the PVDIS experiment at JLab, for RES I settings.

Asymmetry results on $\vec e-^2$H parity-violating scattering from the PVDIS experiment at JLab, for RES II settings.

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Measurement of azimuthal asymmetries in inclusive charged dipion production in $e^+e^-$ annihilations at $\sqrt{s}$ = 3.65 GeV

The BESIII collaboration Ablikim, M. ; Achasov, M.N. ; Ai, X.C. ; et al.
Phys.Rev.Lett. 116 (2016) 042001, 2016.
Inspire Record 1384778 DOI 10.17182/hepdata.73802

We present a measurement of the azimuthal asymmetries of two charged pions in the inclusive process $e^+e^-\rightarrow \pi\pi X$ based on a data set of 62 $\rm{pb}^{-1}$ at the center-of-mass energy $\sqrt{s}=3.65$ GeV collected with the BESIII detector. These asymmetries can be attributed to the Collins fragmentation function. We observe a nonzero asymmetry, which increases with increasing pion momentum. As our energy scale is close to that of the existing semi-inclusive deep inelastic scattering experimental data, the measured asymmetries are important inputs for the global analysis of extracting the quark transversity distribution inside the nucleon and are valuable to explore the energy evolution of the spin-dependent fragmentation function.

2 data tables match query

Results of $A_{\rm UL}$ and $A_{\rm UC}$ in each ($z_{1},z_{2}$) and $p_{t}$ bin. The averages $\langle z_i\rangle$, $\langle p_t\rangle$ and $\rm \frac{\langle sin^2\theta_{2}\rangle }{\rm \langle 1+cos^2\theta_{2} \rangle }$ are also given.

Results of $A_{\rm UL}$ and $A_{\rm UC}$ in each ($z_{1},z_{2}$) and $p_{t}$ bin. The averages $\langle z_i\rangle$, $\langle p_t\rangle$ and $\rm \frac{\langle sin^2\theta_{2}\rangle }{\rm \langle 1+cos^2\theta_{2} \rangle }$ are also given.


Inclusive hadron photoproduction from longitudinally polarized protons and deuterons.

The E155 collaboration Anthony, P.L. ; Arnold, R.G. ; Averett, T. ; et al.
Phys.Lett.B 458 (1999) 536-544, 1999.
Inspire Record 495554 DOI 10.17182/hepdata.28074

We report measurements of the asymmetry A_parallel for inclusive hadron production on longitudinally polarized proton and deuteron targets by circularly polarized photons. The photons were produced via internal and external bremsstrahlung from an electron beam of 48.35 GeV. Asymmetries for both positive and negative signed hadrons, and a subset of identified pions, were measured in the momentum range 10<P<30 GeV at 2.75 and 5.5 degrees. Small non-zero asymmetries are observed for the proton, while the deuteron results are consistent with zero. Recent calculations do not describe the data well.

4 data tables match query

The asymmetry for polarized photoproduction of inclusive hadrons from a polarized proton target. The errors are statistical only.

The asymmetry for polarized photoproduction of inclusive identified pions from a polarized proton target. The errors are statistical only.

The asymmetry for polarized photoproduction of inclusive hadrons from a polarized deuteron target. The errors are statistical only.

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FORWARD - BACKWARD CHARGE ASYMMETRY IN e+ e- ---> HADRON JETS

The AMY collaboration Stuart, D. ; Breedon, R.E. ; Kim, G.N. ; et al.
Phys.Rev.Lett. 64 (1990) 983, 1990.
Inspire Record 283082 DOI 10.17182/hepdata.19965

The forward-backward asymmetry of quarks produced in e+e− annihilations, summed over all flavors, is measured at √s between 50 and 60.8 GeV. Methods of determining the charge direction of jet pairs are discussed. The asymmetry is found to agree with the five-flavor standard model.

1 data table match query

Forward backward asymmetry summed over all flavours of quarks.


Measurement of the target asymmetry of eta and pi0 photoproduction on the proton.

Bock, A. ; Anton, G. ; Beulertz, W. ; et al.
Phys.Rev.Lett. 81 (1998) 534-537, 1998.
Inspire Record 474492 DOI 10.17182/hepdata.19492

At the tagged photon facility PHOENICS at the Bonn accelerator ELSA a measurement of the target asymmetry of the reaction γp→pη from threshold to 1150 MeV has been performed. Simultaneously the reaction γp→pπ0 has been measured in the first resonance region. Results are presented for both reactions. The target asymmetry data are suited to put considerable constraints on the model parameters used for the theoretical description of meson photoproduction.

3 data tables match query

The errors include statistical and systematic errors added in quadrature. The target asymmetry determines as the rates belonging to different polarization states: (N_pol-up-N_pol_down)/(N_pol-up+N_pol_down).

The errors include statistical and systematic errors added in quadrature. The target asymmetry determines as the rates belonging to different polarization states: (N_pol-up-N_pol_down)/(N_pol-up+N_pol_down).

The errors include statistical and systematic errors added in quadrature. The target asymmetry determines as the rates belonging to different polarization states: (N_pol-up-N_pol_down)/(N_pol-up+N_pol_down).


Measurement of the forward - backward asymmetries for charm and bottom quark pair productions at S**(1/2) = 58-GeV with electron tagging

The TOPAZ collaboration Nakano, E. ; Enomoto, R. ; Iwasaki, M. ; et al.
Phys.Lett.B 340 (1994) 135-142, 1994.
Inspire Record 39496 DOI 10.17182/hepdata.28532

We have measured, with electron tagging, the forward-backward asymmetries of charm- and bottom-quark pair productions at $\langle \sqrt{s} \rangle$=58.01GeV, based on 23,783 hadronic events selected from a data sample of 197pb$~{-1}$ taken with the TOPAZ detector at TRISTAN. The measured forward-backward asymmetries are $A_{FB}~c = -0.49 \pm 0.20(stat.) \pm 0.08 (sys.)$ and $A_{FB}~b = -0.64 \pm 0.35(stat.) \pm 0.13 (sys.)$, which are consistent with the standard model predictions.

1 data table match query

No description provided.


Measurement of A(c) with charmed mesons at SLD.

The SLD collaboration Abe, Kenji ; Abe, Koya ; Abe, Toshinori ; et al.
Phys.Rev.D 63 (2001) 032005, 2001.
Inspire Record 533573 DOI 10.17182/hepdata.41721

We present a direct measurement of the parity-violation parameter $A_c$ in the coupling of the $Z^0$ to $c$-quarks with the SLD detector. The measurement is based on a sample of 530k hadronic $Z^0$ decays, produced with a mean electron-beam polarization of $|P_e| = 73 %$. The tagging of $c$-quark events is performed using two methods: the exclusive reconstruction of $D^{\ast+}$, $D^+$, and $D^0$ mesons, and the soft-pions ($\pi_s$) produced in the decay of $D^{\ast+}\to D^0 \pi_s^+$. The large background from $D$ mesons produced in $B$ hadron decays is separated efficiently from the signal using precision vertex information. The combination of these two methods yields $A_c = 0.688 \pm 0.041.$

1 data table match query

CONST(NAME=A_C) is connected with the forward-backward asymmetry by following way: ASYM(NAME=FB) = ABS(P_e)*CONST(NAME=A_C)*2z/(1 + z**2), where z = cos(theta), theta is the polar angle of the outgoing fermion relative to the incident electron, P_e is the longitudinal polarization of the electron beam. Two values for constant A_c were obtained using two different c-quark tagging methods: exclusive charmed-meson reconstruction (C=EXCLUSIVE) and inclusive soft-pion analysis (C=SOFT_PIONS).


Enhanced leading production of D+- and D*+- in 250-GeV pi+- - nucleon interactions

The E769 collaboration Alves, G.A. ; Amato, S. ; Anjos, J.C. ; et al.
Phys.Rev.Lett. 72 (1994) 812-815, 1994.
Inspire Record 361344 DOI 10.17182/hepdata.42499

A leading charm meson is one with longitudinal momentum fraction, xF>0, whose light quark (or antiquark) is of the same type as one of the quarks in the beam particles. We report on the production asymmetry, A=[σ(leading-σ(nonleading)]/[σ(leading)+σ(nonleading)] as a function of xF. The data consist of 1500 fully reconstructed D± and D*± decays in Fermilab experiment E 769. We find a significant asymmetry for the production of charm quarks is not expected in perturbative quantum chromodynamics.

2 data tables match query

Asymmetry as function of XL.

Asymmetry as function of PT**2.


Beam-spin asymmetries in the azimuthal distribution of pion electroproduction.

The HERMES collaboration Airapetian, A. ; Akopov, Z. ; Amarian, M. ; et al.
Phys.Lett.B 648 (2007) 164-170, 2007.
Inspire Record 735612 DOI 10.17182/hepdata.41783

A measurement of the beam-spin asymmetry in the azimuthal distribution of pions produced in semi-inclusive deep-inelastic scattering off protons is presented. The measurement was performed using the {HERMES} spectrometer with a hydrogen gas target and the longitudinally polarized 27.6 GeV positron beam of HERA. The sinusoidal amplitude of the dependence of the asymmetry on the angle $\phi$ of the hadron production plane around the virtual photon direction relative to the lepton scattering plane was measured for $\pi^+,\pi^-$ and $\pi^0$ mesons. The dependence of this amplitude on the Bjorken scaling variable and on the pion fractional energy and transverse momentum is presented. The results are compared to theoretical model calculations.

6 data tables match query

Beam SSA as a function of Z, X, hadronic PT and Q**2.

Beam SSA as a function of Z, X, hadronic PT and Q**2.

Beam SSA as a function of Z, X, hadronic PT and Q**2.

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Asymmetries in the production of Lambda0 in 250-GeV/c pi+-, K+- and p nucleon interactions.

The E769 collaboration Alves, G.A ; Amato, S ; Anjos, J.C ; et al.
Phys.Lett.B 559 (2003) 179-186, 2003.
Inspire Record 615414 DOI 10.17182/hepdata.41928

Using data from Fermilab fixed-target experiment E769, we have measured particle-antiparticle production asymmetries for Lambda0 hyperons in 250 GeV/c pi+-, K+- and p -- nucleon interactions. The asymmetries are measured as functions of Feynman-x (x_F) and p_t^2 over the ranges -0.12<=x_F<=0.12 and 0<=p_t^2<=3 (GeV/c)^2 (for positive beam) and -0.12<=x_F<=0.4 and 0<=p_t^2<=10 (GeV/c)^2 (for negative beam). We find substantial asymmetries, even at x_F around zero. We also observe leading-particle-type asymmetries. These latter effects are qualitatively as expected from valence-quark content of the target and variety of projectiles studied.

4 data tables match query

LAMBDA production asymmetries versus XL for the positive beams.

LAMBDA production asymmetries versus PT**2 for the positive beams.

LAMBDA production asymmetries versus XL for the negative beams.

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Asymmetries in the production of Lambda0, Xi-, and Omega- hyperons in 500-GeV/c pi- nucleon interactions.

The E791 collaboration Aitala, E.M. ; Amato, S. ; Anjos, J.C. ; et al.
Phys.Lett.B 496 (2000) 9-18, 2000.
Inspire Record 532973 DOI 10.17182/hepdata.42997

Using data from Fermilab fixed-target experiment E791, we have measured particle-antiparticle production asymmetries for lambda zero, cascade minus, and omega minus hyperons in pi minus-nucleon interactions at 500 GeV/c. The asymmetries are measured as functions of Feynman-x (x_F) and pt^2 over the ranges of -0.12 GE x_F LE 0.12 and 0 GE pt^2 LE 4 (GeV/c)^2. We find substantial asymmetries, even at x_F = 0. We also observe leading-particle- type asymmetries which qualitatively agree with theoretical predictions.

7 data tables match query

No description provided.

No description provided.

No description provided.

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Measurement of the forward - backward asymmetry of e+ e- ---> c anti-c at s**(1/2) = 57.95-GeV

The TOPAZ collaboration Nakano, E. ; Enomoto, R. ; Abe, K. ; et al.
Phys.Lett.B 314 (1993) 471-476, 1993.
Inspire Record 361662 DOI 10.17182/hepdata.28846

Measurements of the forward-backward asymmetry of e + e − → cc events were carried out at a mean √s energy of 57.95 GeV at TRISTAN, KEK. The cc events were tagged either by the full-reconstruction of D ∗± or the inclusive P T spectrum of π s ± from D ∗± → D 0 ( D 0 )π s ± . The forward-backward asymmetry was measured to be A FB c = −0.49 −0.13 +0.14 (stat.) ± 0.06 (syst.), consistent with the standard model.

1 data table match query

No description provided.


Measurement of forward - backward charge asymmetry in the process of b quark production in e+ e- annihilation around s**(1/2) = 60-GeV

The VENUS collaboration Shirakata, M. ; Utsumi, M. ; Abe, K. ; et al.
Phys.Lett.B 278 (1992) 499-505, 1992.
Inspire Record 322085 DOI 10.17182/hepdata.29242

We have measured the forward-backward charge asymmetry in the process of b-quark production in e + e − annihilation at TRISTAN. It was made possible by detecting prompt leptons from b-quarks. The obtained asymmetry is A = −0.55±0.15±0.08. If corrected for B-meson mixing effects with the assumptions given in the text, the asymmetry becomes A = f −0.78±0.21±0.11, which is consistent with the prediction of the standard model, namely the assignment of the b-quark to the isospin doublet of the third quark generation.

2 data tables match query

Data uncorrected for meson mixing effects.

Data corrected for meson mixing effects.


A Measurement of the Weak Axial Couplings of the $b$ and $c$ Quark

The JADE collaboration Elsen, E. ; Allison, J. ; Ambrus, K. ; et al.
Z.Phys.C 46 (1990) 349-360, 1990.
Inspire Record 282535 DOI 10.17182/hepdata.15241

The forward-backward charge asymmetries of theb andc quarks are measured with the JADE detector at PETRA at\(\sqrt s= 35\) GeV and 44 GeV using both electrons and muons to tag the heavy quarks. At\(\sqrt s= 35\) GeV, a simultaneous fit for the two asymmetries yields the resultAb=−9.3±5.2% (state.) ndAc=−9.6±4.0% (stat.). The systematic errors are comparable with the statistical uncertainties. Combining the measurements at both energies and alternately constraining the weak coupling of thec andb quark to their Standard Model values (ac=1,ab=−1) increases the precision of the measurement of coupling constant of the other quark. Using this procedureab=−0.72±0.34 andac=0.79±0.40, where the numbers are corrected for\(B\bar B - mixing\) and the errors include both statistical and systematic contributions. The mixing parameter for continuum\(b\bar b - production\) is determined to be χ-0.24±0.12 if both heavy quark coupling constants are constrained to their values in the Standard Model.

4 data tables match query

Results of simultaneous fit to both asymmetries. This table is for the CHARMED quark.

Results of simultaneous fit to both asymmetries. This table is for the BOTTOM quark.

Results for BOTTOM quark asymmetry with c asymmetry constrained to the standard model value.

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A Measurement of the Charmed Quark Asymmetry in $e^+ e^-$ Annihilation

The JADE collaboration Ould-Saada, F. ; Allison, J. ; Ambrus, K. ; et al.
Z.Phys.C 44 (1989) 567, 1989.
Inspire Record 278937 DOI 10.17182/hepdata.15357

The charmed quark charge asymmetry has been measured at the average centre of mass energy of 35 GeV with the JADE detector at thee+e− storage ring PETRA. Charmed quarks were identified byD*± tagging using the ΔM technique.D*± mesons were reconstructed through their decay intoD0 mesons resulting in (Kπ) π and (K π π π) π final states. The measured charge asymmetryA=−0.149±0.067 is in agreement with the expectation from the electroweak interference effect in quantum flavour dynamics (QFD).

1 data table match query

CHARMED quark charge asymmetry.


Measurement of $\Z^0 \to b \bar{b}$ Decay Properties

The L3 collaboration Adeva, B. ; Adriani, O. ; Aguilar-Benitez, M. ; et al.
Phys.Lett.B 241 (1990) 416-424, 1990.
Inspire Record 295040 DOI 10.17182/hepdata.29716

We have measured the properties of Z 0 → b b decays using a sample of 944 inclusive muon events, corresponding to 18 000 hadron events obtained with the L3 detector at LEP. We measured the partial decay width of the Z 0 into b b , Γ b b =353±48 MeV , and we determined the vector coupling of the Z 0 to the b quark; g rmv 2 (b)=0.095±0.047. We measured the forward-backward charge asymmetry in e + e − → b b events at √ s ≈ M v , and obtained A b b =13.3±9.9% .

1 data table match query

BOTTOM quark charge asymmetry measurement.


Improving constraints on gluon spin-momentum correlations in transversely polarized protons via midrapidity open-heavy-flavor electrons in $p^{\uparrow}+p$ collisions at $\sqrt{s}=200$ GeV

The PHENIX collaboration Abdulameer, N.J. ; Acharya, U. ; Aidala, C. ; et al.
Phys.Rev.D 107 (2023) 052012, 2023.
Inspire Record 2072832 DOI 10.17182/hepdata.130883

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.

1 data table match query

Data from Figure 1 of open heavy flavor $e^{\pm}$ transverse single-spin asymmetries in transversely polarized p+p collisions as a function of $p_{T}$.


Measurement of the angular distribution of electrons from W ---> e neutrino decays observed in p anti-p collisions at s**(1/2) = 1.8-TeV

The D0 collaboration Abbott, B. ; Abolins, M. ; Abramov, V. ; et al.
Phys.Rev.D 63 (2001) 072001, 2001.
Inspire Record 533572 DOI 10.17182/hepdata.41717

We present the first measurement of the electron angular distribution parameter alpha_2 in W to e nu events produced in proton-antiproton collisions as a function of the W boson transverse momentum. Our analysis is based on data collected using the D0 detector during the 1994--1995 Fermilab Tevatron run. We compare our results with next-to-leading order perturbative QCD, which predicts an angular distribution of (1 +/- alpha_1 cos theta* + alpha_2 cos^2 theta*), where theta* is the polar angle of the electron in the Collins-Soper frame. In the presence of QCD corrections, the parameters alpha_1 and alpha_2 become functions of p_T^W, the W boson transverse momentum. This measurement provides a test of next-to-leading order QCD corrections which are a non-negligible contribution to the W boson mass measurement.

1 data table match query

Angular distributions of the emitted charged lepton is fitted to the formula d(sig)/d(pt**2)/dy/d(cos(theta*)) = const*(1 +- alpha_1*cos(theta*) + alpha_2*(cos(theta*))**2). The angle theta* is measured in the Collins-Soper frame. alpha_1 velues are calculated based on the measured PT(W) of each event. Possible variations of alpha_1 are treated as a source of systematic uncertainty.


Transverse single-spin asymmetry of midrapidity $\pi^{0}$ and $\eta$ mesons in $p$+Au and $p$+Al collisions at $\sqrt{s_{_{NN}}}=$ 200 GeV

The PHENIX collaboration Abdulameer, N.J. ; Acharya, U. ; Aidala, C. ; et al.
Phys.Rev.D 107 (2023) 112004, 2023.
Inspire Record 2641468 DOI 10.17182/hepdata.139098

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.

2 data tables match query

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 $p_{T}$.


Transverse single spin asymmetries of forward neutrons in $p+p$, $p+$Al and $p+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV as a function of transverse and longitudinal momenta

The PHENIX collaboration Acharya, U.A. ; Aidala, C. ; Akiba, Y. ; et al.
Phys.Rev.D 105 (2022) 032004, 2022.
Inspire Record 1944868 DOI 10.17182/hepdata.131759

In 2015 the PHENIX collaboration at the Relativistic Heavy Ion Collider recorded $p+p$, $p+$Al, and $p+$Au collision data at center of mass energies of $\sqrt{s_{_{NN}}}=200$ GeV with the proton beam(s) transversely polarized. At very forward rapidities $\eta>6.8$ relative to the polarized proton beam, neutrons were detected either inclusively or in (anti)correlation with detector activity related to hard collisions. The resulting single spin asymmetries, that were previously reported, have now been extracted as a function of the transverse momentum of the neutron as well as its longitudinal momentum fraction $x_F$. The explicit kinematic dependence, combined with the correlation information allows for a closer look at the interplay of different mechanisms suggested to describe these asymmetries, such as hadronic interactions or electromagnetic interactions in ultra-peripheral collisions, UPC. Events that are correlated with a hard collision indeed display a mostly negative asymmetry that increases in magnitude as a function of transverse momentum with only little dependence on $x_F$. In contrast, events that are not likely to have emerged from a hard collision display positive asymmetries for the nuclear collisions with a kinematic dependence that resembles that of a UPC based model. Because the UPC interaction depends strongly on the charge of the nucleus, those effects are very small for $p+p$ collisions, moderate for $p+$Al collisions, and large for $p+$Au collisions.

8 data tables match query

Measured forward neutron single spin asymmetries in p+p collisions as a function of pT in bins of xF

Measured forward neutron single spin asymmetries in p+Al collisions as a function of pT in bins of xF

Measured forward neutron single spin asymmetries in p+Au collisions as a function of pT in bins of xF

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Transverse-single-spin asymmetries of charged pions at midrapidity in transversely polarized $p{+}p$ collisions at $\sqrt{s}=200$ GeV

The PHENIX collaboration Acharya, U.A. ; Aidala, C. ; Akiba, Y. ; et al.
Phys.Rev.D 105 (2022) 032003, 2022.
Inspire Record 1988071 DOI 10.17182/hepdata.129284

In 2015, the PHENIX collaboration has measured single-spin asymmetries for charged pions in transversely polarized proton-proton collisions at the center of mass energy of $\sqrt{s}=200$ GeV. The pions were detected at central rapidities of $|\eta|<0.35$. The single-spin asymmetries are consistent with zero for each charge individually, as well as consistent with the previously published neutral-pion asymmetries in the same rapidity range. However, they show a slight indication of charge-dependent differences which may suggest a flavor dependence in the underlying mechanisms that create these asymmetries.

1 data table match query

Measured charged pion single spin asymmetries in p+p collisions as a function of pT


Transverse momentum dependent forward neutron single spin asymmetries in transversely polarized $p+p$ collisions at $\sqrt{s}=200$ GeV

The PHENIX collaboration Acharya, U.A. ; Aidala, C. ; Akiba, Y. ; et al.
Phys.Rev.D 103 (2021) 032007, 2021.
Inspire Record 1834002 DOI 10.17182/hepdata.106656

In 2015, the PHENIX collaboration has measured very forward ($\eta>6.8$) single-spin asymmetries of inclusive neutrons in transversely polarized proton-proton and proton-nucleus collisions at a center of mass energy of 200 GeV. A previous publication from this data set concentrated on the nuclear dependence of such asymmetries. In this measurement the explicit transverse-momentum dependence of inclusive neutron single spin asymmetries for proton-proton collisions is extracted using a bootstrapping-unfolding technique on the transverse momenta. This explicit transverse-momentum dependence will help improve the understanding of the mechanisms that create these asymmetries.

4 data tables match query

Measured and unfolded forward neutron single spin asymmetries using 3rd order polynomial parameterization in unfolding

Measured and unfolded forward neutron single spin asymmetries using a Power law parameterization in unfolding

Measured and unfolded forward neutron single spin asymmetries using an exponential parameterization in unfolding

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Collins asymmetries in inclusive charged $KK$ and $K\pi$ pairs produced in $e^+e^-$ annihilation

The BaBar collaboration Lees, J.P. ; Poireau, V. ; Tisserand, V. ; et al.
Phys.Rev.D 92 (2015) 111101, 2015.
Inspire Record 1377201 DOI 10.17182/hepdata.73750

We present measurements of Collins asymmetries in the inclusive process $e^+e^- \rightarrow h_1 h_2 X$, $h_1h_2=KK,\, K\pi,\, \pi\pi$, at the center-of-mass energy of 10.6 GeV, using a data sample of 468 fb$^{-1}$ collected by the BaBar experiment at the PEP-II $B$ factory at SLAC National Accelerator Center. Considering hadrons in opposite thrust hemispheres of hadronic events, we observe clear azimuthal asymmetries in the ratio of unlike- to like-sign, and unlike- to all charged $h_1 h_2$ pairs, which increase with hadron energies. The $K\pi$ asymmetries are similar to those measured for the $\pi\pi$ pairs, whereas those measured for high-energy $KK$ pairs are, in general, larger.

6 data tables match query

Light quark ($uds$) Collins asymmetries obtained by fitting the U/L and U/C double ratios as a function of ($z_1$,$z_2$) for kaon pairs. In the first column, the $z$ bins and their respective mean values for the kaon in one hemisphere are reported; in the following column, the same variables for the second kaon are shown; in the third column the mean value of $\sin^2\theta_{th}/(1+\cos^2\theta_{th})$ is summarized, calculated in the RF12 frame; in the last two columns the asymmetry results are summarized. The mean values of the quantities reported in the table are calculated by summing the corresponding values for each $KK$ pair and dividing by the number of $KK$ pairs that fall into each ($z_1$,$z_2$) interval. Note that the $A^{UL}$ and $A^{UC}$ results are strongly correlated since they are obtained by using the same data set.

Light quark ($uds$) Collins asymmetries obtained by fitting the U/L and U/C double ratios as a function of ($z_1$,$z_2$) for kaon pairs. In the first column, the $z$ bins and their respective mean values for the kaon in one hemisphere are reported; in the following column, the same variables for the second kaon are shown; in the third column the mean value of $\sin^2\theta_{2}/(1+\cos^2\theta_{2})$ is summarized, calculated in the RF0 frame; in the last two columns the asymmetry results are summarized. The mean values of the quantities reported in the table are calculated by summing the corresponding values for each $KK$ pair and dividing by the number of $KK$ pairs that fall into each ($z_1$,$z_2$) interval. Note that the $A^{UL}$ and $A^{UC}$ results are strongly correlated since they are obtained by using the same data set.

Light quark ($uds$) Collins asymmetries obtained by fitting the U/L and U/C double ratios as a function of ($z_1$,$z_2$) for $K\pi$ hadron pairs. In the first column, the $z$ bins and their respective mean values for the hadron ($K$ or $\pi$) in one hemisphere are reported; in the following column, the same variables for the second hadron ($K$ or $\pi$) are shown; in the third column the mean value of $\sin^2\theta_{th}/(1+\cos^2\theta_{th})$ is summarized, calculated in the RF12 frame; in the last two columns the asymmetry results are summarized. The mean values of the quantities reported in the table are calculated by summing the corresponding values for each $K\pi$ pair and dividing by the number of $K\pi$ pairs that fall into each ($z_1$,$z_2$) interval. Note that the $A^{UL}$ and $A^{UC}$ results are strongly correlated since they are obtained by using the same data set.

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A new measurement of the Collins and Sivers asymmetries on a transversely polarised deuteron target

The COMPASS collaboration Ageev, E.S. ; Alexakhin, V.Yu. ; Alexandrov, Yu. ; et al.
Nucl.Phys.B 765 (2007) 31-70, 2007.
Inspire Record 729695 DOI 10.17182/hepdata.48535

New high precision measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarised 6LiD target are presented. The data were taken in 2003 and 2004 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV/c. Both the Collins and Sivers asymmetries turn out to be compatible with zero, within the present statistical errors, which are more than a factor of 2 smaller than those of the published COMPASS results from the 2002 data. The final results from the 2002, 2003 and 2004 runs are compared with naive expectations and with existing model calculations.

24 data tables match query

Collins asymmetry against PT for all negative hadrons.

Collins asymmetry against Bjorken X for all negative hadrons.

Collins asymmetry against Z for all negative hadrons.

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Measurement of parity-violating spin asymmetries in W$^{\pm}$ production at midrapidity in longitudinally polarized $p$$+$$p$ collisions

The PHENIX collaboration Adare, A. ; Aidala, C. ; Ajitanand, N.N. ; et al.
Phys.Rev.D 93 (2016) 051103, 2016.
Inspire Record 1365091 DOI 10.17182/hepdata.73691

We present measurements from the PHENIX experiment of large parity-violating single spin asymmetries of high transverse momentum electrons and positrons from $W^\pm/Z$ decays, produced in longitudinally polarized $p$$+$$p$ collisions at center of mass energies of $\sqrt{s}$=500 and 510~GeV. These asymmetries allow direct access to the anti-quark polarized parton distribution functions due to the parity-violating nature of the $W$-boson coupling to quarks and anti-quarks. The results presented are based on data collected in 2011, 2012, and 2013 with an integrated luminosity of 240 pb$^{-1}$, which exceeds previous PHENIX published results by a factor of more than 27. These high $Q^2$ data provide an important addition to our understanding of anti-quark parton helicity distribution functions.

1 data table match query

Longitudinal single-spin asymmetries, $A_L$, for the 2011 and 2012 data sets (combined) spanning the entire $\eta$ range of PHENIX ($\left|\eta\right|<0.35$), for the 2013 data set separated into two $\eta$ bins, and for the combined 2011-2013 data sets.


Measurement of the spin asymmetry in the photoproduction of pairs of high p(T) hadrons at HERMES.

The HERMES collaboration Airapetian, A. ; Akopov, N. ; Amarian, M. ; et al.
Phys.Rev.Lett. 84 (2000) 2584-2588, 2000.
Inspire Record 503784 DOI 10.17182/hepdata.43919

We present a measurement of the longitudinal spin asymmetry A_|| in photoproduction of pairs of hadrons with high transverse momentum p_T. Data were accumulated by the HERMES experiment using a 27.5 GeV polarized positron beam and a polarized hydrogen target internal to the HERA storage ring. For h+h- pairs with p_T^h_1 > 1.5 GeV/c and p_T^h_2 > 1.0 GeV/c, the measured asymmetry is A_|| = -0.28 +/- 0.12 (stat.) +/- 0.02 (syst.). This negative value is in contrast to the positive asymmetries typically measured in deep inelastic scattering from protons, and is interpreted to arise from a positive gluon polarization.

1 data table match query

Asymmetry measurement with a PT cut of 1.5 GeV on the hadron with the higher PT, and 1.0 GeV on the hadron with the lower PT.


Spin correlation in t anti-t production from p anti-p collisions at S**(1/2) = 1.8-TeV

The D0 collaboration Abbott, B. ; Abolins, M. ; Abramov, V. ; et al.
Phys.Rev.Lett. 85 (2000) 256-261, 2000.
Inspire Record 524260 DOI 10.17182/hepdata.42996

The D0 collaboration has performed a study of spin correlation in tt-bar production for the process tt-bar to bb-bar W^+W^-, where the W bosons decay to e-nu or mu-nu. A sample of six events was collected during an exposure of the D0 detector to an integrated luminosity of approximately 125 pb^-1 of sqrt{s}=1.8 TeV pp-bar collisions. The standard model (SM) predicts that the short lifetime of the top quark ensures the transmission of any spin information at production to the tt-bar decay products. The degree of spin correlation is characterized by a correlation coefficient k. We find that k>-0.25 at the 68% confidence level, in agreement with the SM prediction of k=0.88.

1 data table match query

No description provided.


First measurement of the transverse spin asymmetries of the deuteron in semi-inclusive deep inelastic scattering.

The COMPASS collaboration Alexakhin, V.Yu. ; Alexandrov, Yu. ; Alexeev, G.D. ; et al.
Phys.Rev.Lett. 94 (2005) 202002, 2005.
Inspire Record 677550 DOI 10.17182/hepdata.48553

First measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarized 6-LiD target are presented. The data were taken in 2002 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV/c. The Collins asymmetry turns out to be compatible with zero, as does the measured Sivers asymmetry within the present statistical errors.

6 data tables match query

Asymmetries as a function of X for LEADING hadrons.

Asymmetries as a function of Z for LEADING hadrons.

Asymmetries as a function of PT for LEADING hadrons.

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Measurement of the polarized forward - backward asymmetry of Z0 ---> b anti-b using a lifetime tag and momentum weighted track charge

The SLD collaboration Abe, K. ; Abt, I. ; Ahn, C.J. ; et al.
SLAC-PUB-6979, 1995.
Inspire Record 398301 DOI 10.17182/hepdata.18618

None

1 data table match query

No description provided.


Measurement of the left-right forward - backward asymmetry for charm quarks with D*+ and D+ mesons

The SLD collaboration Abe, K. ; Abt, I. ; Ahn, C.J. ; et al.
Phys.Rev.Lett. 75 (1995) 3609-3613, 1995.
Inspire Record 404272 DOI 10.17182/hepdata.19646

We present a direct measurement of Ac=2vcac(vc2+ac2) from the left-right forward-backward asymmetry of D*+ and D+ mesons in Z0 events produced with the longitudinally polarized SLAC Linear Collider beam. These Z0→cc¯ events are tagged on the basis of event kinematics and decay topology from a sample of hadronic Z0 decays recorded by the SLAC Large Detector. We measure Ac0=0.73±0.22(stat)±0.10(syst).

1 data table match query

No description provided.


Direct measurement of leptonic coupling asymmetries with polarized Z's.

The SLD collaboration Abe, K. ; Akagi, T. ; Allen, N.J. ; et al.
Phys.Rev.Lett. 79 (1997) 804-808, 1997.
Inspire Record 442260 DOI 10.17182/hepdata.19552

We present direct measurements of the $Z~0$-lepton coupling asymmetry parameters, $A_e$, $A_\mu$, and $A_\tau$, based on a data sample of 12,063 leptonic $Z~0$ decays collected by the SLD detector. The $Z$ bosons are produced in collisions of beams of polarized $e~-$ with unpolarized $e~+$ at the SLAC Linear Collider. The couplings are extracted from the measurement of the left-right and forward-backward asymmetries for each lepton species. The results are: $A_e=0.152 \pm 0.012 {(stat)} \pm 0.001 {(syst)}$, $A_\mu=0.102 \pm 0.034 \pm 0.002$, and $A_\tau=0.195 \pm 0.034 \pm 0.003$.

1 data table match query

No description provided.


Inclusive Electron Production From Heavy Quarks in $e^+ e^-$ Annihilation at 34.6-{GeV} Center-of-mass Energy

The TASSO collaboration Althoff, M. ; Braunschweig, W. ; Kirschfink, F.J. ; et al.
Phys.Lett.B 146 (1984) 443-449, 1984.
Inspire Record 202782 DOI 10.17182/hepdata.30507

The production of electrons by bottom and charm hadrons has been studied in e + e − annihilation at 34.6 GeV center of mass energy. It is observed that the b quark fragmentation function is peaked at large values of the scaling variable z with 〈 z b 〉 = 0.84 +0.15 + 0.15 −0.10 − 0.11 . For c quarks 〈 z c 〉 = 0.57 +0.10 + 0.05 −0.09 − 0.06 is observed. A forward-backward charge asymmetry of A = −0.25 ± 0.22 was measured in b production.

2 data tables match query

THE VALUE OF ASYMMETRY WAS DETERMINED USING A SAMPLE OF PROMPT ELECTRONS.

THE VALUE OF ASYMMETRY WAS DETERMINED USING A SAMPLE OF PROMPT ELECTRONS.


The Forward - backward asymmetry of e+ e- ---> b anti-b and e+ e- ---> c anti-c using leptons in hadronic Z0 decays

The OPAL collaboration Acton, P.D. ; Akers, R. ; Alexander, G. ; et al.
Z.Phys.C 60 (1993) 19-36, 1993.
Inspire Record 356097 DOI 10.17182/hepdata.14320

The forward-backward asymmetries of$$e^ + e^ - \to Z^0 \to b\bar b and e^ + e^ - \to Z^0 \to c\bar c$$

5 data tables match query

Measurement of the asymmetry in b-quark production on the Z0 peak using a two parameter fit, neglecting the effects of B0-BBAR0 mixing.

Measurement of the asymmetry in b-quark production on the Z0 peak using a two parameter fit and correcting for B0-BBAR0 mixing. The second systematic error is due to the uncertainty of the mixing factor.

Measurement of the asymmetry in c-quark production on the Z0 peak using a two parameter fit.

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Measurement of the Forward-Backward Charge Asymmetry and Extraction of $sin^2\Theta^\mbox{eff}_W$ in $p\bar{p} \to Z/\gamma^{*}+X \to e^+e^- +X$ Events Produced at $\sqrt{s} = 1.96$ TeV

The D0 collaboration Abazov, V.M. ; Abbott, B. ; Abolins, M. ; et al.
Phys.Rev.Lett. 101 (2008) 191801, 2008.
Inspire Record 783813 DOI 10.17182/hepdata.52605

We present a measurement of the forward-backward charge asymmetry ($A_{FB}$) in $p\bar{p} \to Z/\gamma^{*}+X \to e^+e^-+X$ events at a center-of-mass energy of 1.96 TeV using 1.1 fb$^{-1}$ of data collected with the D0 detector at the Fermilab Tevatron collider. $A_{FB}$ is measured as a function of the invariant mass of the electron-positron pair, and found to be consistent with the standard model prediction. We use the $A_{FB}$ measurement to extract the effective weak mixing angle sin$^2\Theta^{eff}_W = 0.2327 \pm 0.0018 (stat.) \pm 0.0006 (syst.)$.

1 data table match query

Unfolded forward-backward asymmetry as a function of the di-electron mass.


Production and Muonic Decay of Heavy Quarks in e+ e- Annihilation at 34.5-GeV

The TASSO collaboration Althoff, M. ; Braunschweig, W. ; Kirschfink, F.J. ; et al.
Z.Phys.C 22 (1984) 219, 1984.
Inspire Record 194775 DOI 10.17182/hepdata.16252

The production of prompt muons ine+e− annihilation has been studied at centre of mass energies near 34.5 GeV. The measured semi-muonic branching ratios ofb andc quarks areB(b»Xμv) =0.117±0.028±0.01 andB(c→Xμv)=0.082 ±0.012a−0.01+0.02. The fragmentation functions of heavy quarks are hard, <zb>=0.85a−0.12–0.07+0.10+0.02 and <zc> =0.77a−0.07–0.11+0.05+0.03. Limits have been set on flavour changing neutral current decays:B(b→Xµ+µ−) <0.02 andB(b→Xµ+µ− (95% confidence level).

1 data table match query

THE VALUE OF ASYMMETRY WAS DETERMINED USING A SAMPLE OF PROMPT MUONS.


Heavy Quark Charge Asymmetries With the Cello Detector

The CELLO collaboration Behrend, H.J. ; Criegee, L. ; Field, J.H. ; et al.
Z.Phys.C 47 (1990) 333-342, 1990.
Inspire Record 282536 DOI 10.17182/hepdata.15243

The production ofb andc quarks ine+e− annihilation has been studied with the CELLO detector in the range from 35 GeV up to the highest PETRA energies. The heavy quarks have been tagged by their semileptonic decays. The charge asymmetries forb quarks at 35 and 43 GeV have been found to beAb=−(22.2±8.1)% andAb=−(49.1±16.5)%, respectively, using a method incorporating jet variables and their correlations for the separation of the heavy quarks from the back ground of the lighter quarks. Forc quarks we obtainAc=−(12.9±8.8)% andAc=+(7.7±14.0)%, respectively. The axial vector coupling constants of the heavy quarksc andb are found to beac=+(0.29±0.46) andab=−(1.15±0.41) taking\(B^0 \overline {B^0 } \) mixing into account. The results are in agreement with the expectations from the standard model.

2 data tables match query

BOTTOM quark charge asymmetry.

CHARMED quark charge asymmetry.