HEPData Search

We report on a polarization measurement of inclusive $J/\psi$ mesons in the di-electron decay channel at mid-rapidity at 2 $<p_{T}<$ 6 GeV/$c$ in $p+p$ collisions at $\sqrt{s}$ = 200 GeV. Data were taken with the STAR detector at RHIC. The $J/\psi$ polarization measurement should help to distinguish between different models of the $J/\psi$ production mechanism since they predict different $p_{T}$ dependences of the $J/\psi$ polarization. In this analysis, $J/\psi$ polarization is studied in the helicity frame. The polarization parameter $\lambda_{\theta}$ measured at RHIC becomes smaller towards high $p_{T}$, indicating more longitudinal $J/\psi$ polarization as $p_{T}$ increases. The result is compared with predictions of presently available models.

13 data tables match query

Figure 2 (a)

Uncorrected cos$\theta$ distribution after the combinatorial background subtraction for $2 < p_{T}^{J/\psi} < 3$ GeV/c

Figure 2 (b)

Uncorrected cos$\theta$ distribution after the combinatorial background subtraction for $3 < p_{T}^{J/\psi} < 4$ GeV/c

Figure 2 (c)

Uncorrected cos$\theta$ distribution after the combinatorial background subtraction for $4 < p_{T}^{J/\psi} < 6$ GeV/c

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rivet Analysis
$\Lambda$ Production in $e^+ e^-$ Annihilations at 29-{GeV}: A Comparison With Lund Model Predictions

Baringer, Philip S. ; Abachi, S. ; Beltrami, I. ; et al.

Phys.Rev.Lett. 56 (1986) 1346, 1986.

Inspire Record 17781 DOI 10.17182/hepdata.20257

This paper presents measurements of the inclusive production cross sections of Λ baryons in e+e− annihilations at s=29 GeV. The data sample corresponds to an integrated luminosity of 256 pb−1 collected with the High-Resolution Spectrometer at the SLAC storage ring PEP. Comparisons are made to the predictions of the Lund model. The data are well described with use of a strange-diquark suppression parameter, (usud)(sd), of 0.89 ± 0.10−0.16+0.56, and the measured Λc→Λ+X branching ratio of (23 ± 10)%.

3 data tables match query

Table 1

No description provided.

Table 2

Rapidity relative to thrust axis.

Table 3

Corrected for unobserved moment regions.

$\Lambda$ and $\bar{\Lambda}$ Polarization in $K^\pm p$ Interactions at 32-{GeV}/$c$

The French-Soviet & CERN-Soviet collaborations Faccini-Turluer, M.L. ; Barloutaud, R. ; Cochet, C. ; et al.

Z.Phys.C 1 (1979) 19, 1979.

Inspire Record 132913 DOI 10.17182/hepdata.19291

Data on Λ and$\bar \Lambda $ polarization inK±p interactions at 32 GeV/c are presented. A comparison is made between the results of these two experiments as well as with the data at lower energies. The contribution of the different production mechanisms to the Λ($\bar \Lambda $) polarization are discussed.

2 data tables match query

Table 1

Data are presented on figures only. DATA NOT ENCODED.

Table 2

No description provided.

$\pi^+ p$ Backward Elastic Scattering from 2-GeV/c to 6-GeV/c

Lennox, Arlene J. ; Baker, W.F. ; Eartly, David P. ; et al.

Phys.Rev.D 11 (1975) 1777, 1975.

Inspire Record 90923 DOI 10.17182/hepdata.24918

The backward angular distributions obtained in an experiment at the Zero Gradient Synchrotron of Argonne National Laboratory were used to systematically study the energy dependence of the 180° differential cross section for π+p elastic scattering in the center-of-mass energy region from 2159 to 3487 MeV. At each of 38 incident pion momenta between 2.0 and 6.0 GeV/c, a focusing spectrometer and scintillation counter hodoscopes were used to obtain differential cross sections for typically five pion scattering angles from 141° to 173° in the laboratory. Values for dσdΩ at 180° were then obtained by extrapolation. A resonance model and an interference model were used to perform fits to the energy dependence of dσdΩ (180°). Both models led to good fits to our data and yielded values for the masses, widths, parities, and the product of spin and elasticity for the Δ(2200), Δ(2420), Δ(2850), and Δ(3230) resonances. Our data confirm the existence of the Δ(3230) and require the negative-parity Δ(2200).

39 data tables match query

Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

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$\pi^- p$ Scattering With Charge Exchange in the Region of Small T at 40-{GeV}/$c$ Momentum

The Serpukhov-Brussels-Annecy(LAPP) & Serpukhov-CERN collaborations Binon, F.G. ; Gouanere, M. ; Davydov, V.A. ; et al.

Sov.J.Nucl.Phys. 33 (1981) 663, 1981.

Inspire Record 156874 DOI 10.17182/hepdata.41613

None

2 data tables match query

Table 1

Table 2

D(SIG)/D(T) AT T=0. OBTAINED FROM MODEL EXTRAPOLATION.

$\pi^{-}$C collisions with backward proton emission at 4 and 40 GeV/c

Angelov, N. ; Lutpullaev, S.L. ; Nikitina, V.F. ; et al.

Sov.J.Nucl.Phys. 33 (1981) 98-99, 1981.

Inspire Record 1392857 DOI 10.17182/hepdata.17814

None

13 data tables match query

Table 1

PROTONS MOMENTA LIE IN LAB BACKWARD HEMISPHERE.

Table 2

No description provided.

Table 3

No description provided.

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$\rho^0$ and $\omega$ Meson Inclusive Production by 70-{GeV}/$c$ Protons on the Be Nuclei.

Antipov, Yu.M. ; Bessubov, V.A. ; Budanov, N.P. ; et al.

Sov.J.Nucl.Phys. 36 (1982) 829, 1982.

Inspire Record 177514 DOI 10.17182/hepdata.41184

None

10 data tables match query

Table 1

THE RATIO SIG(RHO0)/SIG(OMEGA) IS FREE PARAMETER.

Table 2

THE RATIO SIG(RHO0)/SIG(OMEGA)=1. AND FIXED.

Table 3

No description provided.

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$\rho^{0}$ Photoproduction in AuAu Collisions at $\sqrt{s_{NN}}$=62.4 GeV with STAR

The STAR collaboration Agakishiev, G. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.

Phys.Rev.C 85 (2012) 014910, 2012.

Inspire Record 919778 DOI 10.17182/hepdata.101342

Vector mesons may be photoproduced in relativistic heavy-ion collisions when a virtual photon emitted by one nucleus scatters from the other nucleus, emerging as a vector meson. The STAR Collaboration has previously presented measurements of coherent $\rho^0$ photoproduction at center of mass energies of 130 GeV and 200 GeV in AuAu collisions. Here, we present a measurement of the cross section at 62.4 GeV; we find that the cross section for coherent $\rho^0$ photoproduction with nuclear breakup is $10.5\pm1.5\pm 1.6$ mb at 62.4 GeV. The cross-section ratio between 200 GeV and 62.4 GeV is $2.8\pm0.6$, less than is predicted by most theoretical models. It is, however, proportionally much larger than the previously observed $15\pm 55$% increase between 130 GeV and 200 GeV.

5 data tables match query

Figure 1 (left)

Acceptance corrected invariant mass distributions for the coherently produced $\rho^0$ candidates collected with trigger A (left) and B (right). The fit function (solid) encompasses the Breit-Wigner (dashed), the mass independent contribution from direct $\pi^+\pi^-$ production (dash-dotted), and the interference term (dotted). The hatched area is the contribution from the combinatorial background. The statistical errors are shown.

Figure 1 (right)

Figure 2

Transverse momentum distribution of the $\rho^0$ candidates (open distribution) overlaid by the combinatorial background estimated with like-sign pairs (not corrected to the acceptance and reconstruction efficiency) and scaled to match in the high transverse momentum region, $p_T$ ≥ 250 MeV/$c$ (hatched distribution). The plot is based on the dataset collected with trigger B.

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$\rm{J}/\psi$ production at low transverse momentum in p+p and d+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.

Phys.Rev.C 93 (2016) 064904, 2016.

Inspire Record 1420183 DOI 10.17182/hepdata.73526

We report on the measurement of $\rm{J}/\psi$ production in the dielectron channel at mid-rapidity (|y|<1) in p+p and d+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV from the STAR experiment at the Relativistic Heavy Ion Collider. The transverse momentum $p_{T}$ spectra in p+p for $p_{T}$ < 4 GeV/c and d+Au collisions for $p_{T}$ < 3 GeV/c are presented. These measurements extend the STAR coverage for $\rm{J}/\psi$ production in p+p collisions to low $p_{T}$. The $<p_{T}^{2}>$ from the measured $\rm{J}/\psi$ invariant cross section in p+p and d+Au collisions are evaluated and compared to similar measurements at other collision energies. The nuclear modification factor for $\rm{J}/\psi$ is extracted as a function of $p_{T}$ and collision centrality in d+Au and compared to model calculations using the modified nuclear Parton Distribution Function and a final-state $\rm{J}/\psi$ nuclear absorption cross section.

6 data tables match query

Table 1

The mean square of $p_T$.

Table 2

Nuclear absorption cross section.

Table 3

The nuclear modicifation factor vs. $p_T$ for $J\psi$ with |y| < 1 in 0-100 percent central d+Au collisions.

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$J/\psi$ and $\psi^\prime$ Production in $\pi^-$ Cu Interaction at 50-{GeV}/$c$

$J/\psi$ polarization in p+p collisions at $\sqrt{s}$ = 200 GeV in STAR

rivet Analysis
$\Lambda$ Production in $e^+ e^-$ Annihilations at 29-{GeV}: A Comparison With Lund Model Predictions

$\Lambda$ and $\bar{\Lambda}$ Polarization in $K^\pm p$ Interactions at 32-{GeV}/$c$

$\pi^+ p$ Backward Elastic Scattering from 2-GeV/c to 6-GeV/c

$\pi^- p$ Scattering With Charge Exchange in the Region of Small T at 40-{GeV}/$c$ Momentum

$\pi^{-}$C collisions with backward proton emission at 4 and 40 GeV/c

$\rho^0$ and $\omega$ Meson Inclusive Production by 70-{GeV}/$c$ Protons on the Be Nuclei.

$\rho^{0}$ Photoproduction in AuAu Collisions at $\sqrt{s_{NN}}$=62.4 GeV with STAR

$\rm{J}/\psi$ production at low transverse momentum in p+p and d+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV