Transverse momentum distributions and yields for $\pi^{\pm}$, $K^{\pm}$, $p$ and $\bar{p}$ in $p+p$ collisions at $\sqrt{s}$=200 and 62.4 GeV at midrapidity are measured by the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC). These data provide important baseline spectra for comparisons with identified particle spectra in heavy ion collisions at RHIC. We present the inverse slope parameter $T_{\rm inv}$, mean transverse momentum $<p_T>$ and yield per unit rapidity $dN/dy$ at each energy, and compare them to other measurements at different $\sqrt{s}$ in $p+p$ and $p+\bar{p}$ collisions. We also present the scaling properties such as $m_T$ scaling, $x_T$ scaling on the $p_T$ spectra between different energies. To discuss the mechanism of the particle production in $p+p$ collisions, the measured spectra are compared to next-to-leading-order or next-to-leading-logarithmic perturbative quantum chromodynamics calculations.
Invariant cross sections for inclusive PI+ and PI- production in P P collisions at a centre-of-mass energy of 200 GeV. There is an additional normalization uncertainty of 9.7 PCT.
Invariant cross sections for inclusive K+ and K- production in P P collisions at a centre-of-mass energy of 200 GeV. There is an additional normalization uncertainty of 9.7 PCT.
Invariant cross sections for inclusive P and PBAR production in P P collisions at a centre-of-mass energy of 200 GeV with feed-down weak decay corrections NOT applied. There is an additional normalization uncertainty of 9.7 PCT.
We present the first measurement of photoproduction of J/psi and of two-photon production of high-mass e+e- pairs in electromagnetic (or ultra-peripheral) nucleus-nucleus interactions, using Au+Au data at sqrt(s_NN) = 200 GeV. The events are tagged with forward neutrons emitted following Coulomb excitation of one or both Au^{star} nuclei. The event sample consists of 28 events with m_{e+e-} > 2 GeV/c^2 with zero like-sign background. The measured cross sections at midrapidity of d\sigma / dy (J/psi + Xn, y=0) = 76 +/- 33 (stat) +/- 11 (syst) micro b and d^2\sigma/dm dy (e^+e^- + Xn, y=0) = 86 +/- 23 (stat) +/- 16 (syst) micro b/(GeV/c^2) for m_{e+e-} \in [2.0,2.8] GeV/c^2 are consistent with various theoretical predictions.
J/PSI N for ultra peripheral Au+Au reactions. The values has been obtained from the fit of the number of counts as a function of the mass of the e+e- pairs detected. The J/PSI pick has been fixed at the known mass ofJ/PSI : 3.097 GeV/c2.
e+e- pairs N in ultra peripherals Au + Au reactions. The values has been obtained from the fit of the number of counts as a function of the mass of the e+e- pairs.The results are given for 3 intervals of masses of the electron pair : 2.0 to 2.3, 2.3 to 2.8 and 2.0 to 2.8 Gev/c2.
J/PSI production cross section at mid rapidity for ultra peripheral Au+Au reactions.
All of the experimental data points presented in the original paper are correct and unchanged (including statistical and systematic uncertainties). However, herein we correct a comparison between the experimental data and a theoretical picture, because we discovered a mistake in the code used. All of the most probable sigma_breakup values differ by less than 0.4 mb from those originally presented. However, the one standard deviation uncertainties (that include contributions from both the statistical and systematic uncertainties on the experimental data points) are approximately 30-60% larger than originally reported. We give a table of the new comparison results and corrected versions of Figs. 8-11 of the original paper and we note that no correction is needed for results from the data-driven method in Fig. 13.
J/PSI invariant (1/(2PI*PT))*D2(N)/DPT/DYRAP versus rapidity in D+AU collisions, over 3 bins of rapidity.
J/PSI invariant (1/(2PI*PT))*D2(N)/DPT/DYRAP versus rapidity in D+AU collisions, over 5 bins of rapidity.
J/PSI invariant (1/(2PI*PT))*D2(N)/DPT/DYRAP versus PT at backward rapidity (-2.2<y<-1.2) in D+AU collisions.
The PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) has measured electrons from heavy flavor (charm and bottom) decays for 0.3 < p_T < 9 GeV/c at midrapidity (|y| < 0.35) in Au+Au collisions at sqrt(s_NN) = 200 GeV. The nuclear modification factor R_AA relative to p+p collisions shows a strong suppression in central Au+Au collisions, indicating substantial energy loss of heavy quarks in the medium produced at RHIC. A large azimuthal anisotropy, v_2, with respect to the reaction plane is observed for 0.5 < p_T < 5 GeV/c indicating non-zero heavy flavor elliptic flow. Both R_AA and v_2 show a p_T dependence different from those of neutral pions. A comparison to transport models which simultaneously describe R_AA(p_T) and v_2(p_T) suggests that the viscosity to entropy density ratio is close to the conjectured quantum lower bound, i.e., near a perfect fluid.
Invariant yield of electrons from heavy-flavor decays for 0-10% central collisions, versus PT.
Invariant yield of electrons from heavy-flavor decays for 10-20% central collisions, versus PT.
Invariant yield of electrons from heavy-flavor decays for 20-40% central collisions, versus PT.
The PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) has measured J/psi production for rapidities 2.2 < y < 2.2 in Au+Au collisions at sqrt(s_NN) = 200 GeV. The J/psi invariant yield and nuclear modification factor R_AA as a function of centrality, transverse momentum and rapidity are reported. A suppression of J/psi relative to binary collision scaling of proton-proton reaction yields is observed. Models which describe the lower energy J/Psi data at the Super Proton Synchrotron (SPS) invoking only J/psi destruction based on the local medium density would predict a significantly larger suppression at RHIC and more suppression at mid rapidity than at forward rapidity. Both trends are contradicted by our data.
J/PSI invariant yield versus transverse momentum for 0-20%, 20-40%, 40-60%, 60-92% centrality at mid rapidity :,-0.35<y<0.35 An up/down correction, to translate each point at the center of it's relative bin, have been applied to the data.
J/PSI invariant yield versus transverse momentum for 0-20%, 20-40%, 40-60%, 60-92% centrality at forward rapidities : absolute value of y belongs to [1.2;2.2] An up/down correction, to translate each point at the center of it's relative bin, have been applied to the data.
Mean PT^2 values for different bins of centrality, at mid rapidities :-0.35<y<0.35,.
J/psi production in d+Au and p+p collisions at sqrt(s_NN) = 200 GeV has been measured by the PHENIX experiment at rapidities -2.2 < y < +2.4. The cross sections and nuclear dependence of J/\psi production versus rapidity, transverse momentum, and centrality are obtained and compared to lower energy p+A results and to theoretical models. The observed nuclear dependence in d+Au collisions is found to be modest, suggesting that the absorption in the final state is weak and the shadowing of the gluon distributions is small and consistent with Dokshitzer-Gribov-Lipatov-Altarelli-Parisi-based parameterizations that fit deep-inelastic scattering and Drell-Yan data at lower energies.
J/PSI differential cross section in P+P reactions( times di-lepton branching ratio B=5.9%) as a function of rapidity.
J/PSI nuclear modification factor RDA,as a function of rapidity.
Total cross-section for J/PSI production in P P reactions. The total cross section is estimated using a pythia calculation, normalized to our data. The di-lepton branching ratio used is 5.9%.The systematic error given is due to the fit. The choice of the PDF and model was estimated to have little impact in the value of the total cross section.
We have measured the magnetic moments of the Σ+ and Σ¯ − hyperons produced by 800-GeV protons incident on a Cu target. We determine the Σ+ magnetic moment to be (2.4613±0.0034±0.0040)μN where the uncertainties are statistical and systematic, respectively. In this first measurement we determine the magnetic moment of the Σ¯ − to be -(2.428±0.036±0.007)μN. The magnetic moments of the Σ+ and Σ¯ − are consistent with each other in magnitude but opposite in sign as required by CPT invariance.
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We have mesured the polarization of 375-GeV/c Σ+ and Σ¯ − hyperons produced by 800-GeV/c protons incident on a Cu target. We find that the Σ+ polarization rises with increasing pt to a maximum of 16% at pt=1.0 GeV/c and then decreases to 10% at pt=1.8 GeV/c. We compare this Σ+ polarization with data at lower energies. The Σ¯ − polarization has been measured for the first time. It has the same sign as the Σ+ but smaller magnitude in a similar kinematical region.
Data from Horizontal targeting.
Data from Vertical targeting.
Data from Horizontal targeting.
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The cross section per nucleon is evaluated with assumption of the linear atomic number dependence. SIG(C=NEUTRINO) and SIG(C=ANTINEUTRINO) are corresponded to the NUMU and NUMUBAR data, respectevly. CLOOP-OVER.
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