Measurements of the kinematic distributions of $J/\psi$ mesons produced in $p-$C, $p-$Ti and $p-$W collisions at $\sqrt{s}=41.6 \mathrm{GeV}$ in the Feynman-$x$ region $-0.34 < x_{F} < 0.14$ and for transverse momentum up to $p_T = 5.4 \mathrm{GeV}/c$ are presented. The $x_F$ and $p_T$ dependencies of the nuclear suppression parameter, $\alpha$, are also given. The results are based on $2.4 \cdot 10^{5}$ $J/\psi$ mesons in both the $e^+ e^-$ and $\mu^{+}\mu^{-}$ decay channels. The data have been collected by the HERA-B experiment at the HERA proton ring of the DESY laboratory. The measurement explores the negative region of $x_{F}$ for the first time. The average value of $\alpha$ in the measured $x_{F}$ region is $0.981 \pm 0.015$. The data suggest that the strong nuclear suppression of $J/\psi$ production previously observed at high $x_F$ turns into an enhancement at negative $x_F$.
J/PSI distributions (dN/dp_T, normalized to their integrals over the measured range) for three targets materials with statistical and systematics uncertainties.
J/PSI distributions (dN/dx_F, normalized to their integrals over the measured range) for three targets materials with statistical and systematics uncertainties.
The parameter Alpha as a function of p_T. Statistical and systematic uncertainties are indicated separately.
The PHENIX experiment has measured mid-rapidity transverse momentum spectra (0.4 < p_T < 4.0 GeV/c) of single electrons as a function of centrality in Au+Au collisions at sqrt(s_NN) = 200 GeV. Contributions to the raw spectra from photon conversions and Dalitz decays of light neutral mesons are measured by introducing a thin (1.7% X_0) converter into the PHENIX acceptance and are statistically removed. The subtracted ``non-photonic'' electron spectra are primarily due to the semi-leptonic decays of hadrons containing heavy quarks (charm and bottom). For all centralities, charm production is found to scale with the nuclear overlap function, T_AA. For minimum-bias collisions the charm cross section per binary collision is N_cc^bar/T_AA = 622 +/- 57 (stat.) +/- 160 (sys.) microbarns.
Value of the Alpha power as used in a fit of dN/dy versus Ncoll of the form A*Ncoll^Alpha, where N is the non photonic electron yield and Ncoll the number of p+p collisions This value only includes data from Au+Au collisions The value of Alpha = 1 is the expectation in the absence of medium effects.
Value of the Alpha power as used in a fit of dN/dy versus Ncoll, of the form A*Ncoll^Alpha, where N is the non photonic electron yield and Ncoll the number of p+p collisions This value is calculated including previous data of p+p collisions, measured by PHENIX, in addition of the Au+Au data The value of Alpha = 1 is the expectation in the absence of medium effects.
Spectrum in transverse momentum of electrons created in open heavy flavor decays, for minimum bias events.
The STAR collaboration at RHIC presents measurements of \Jpsi$\to{e^+e^-}$ at mid-rapidity and high transverse momentum ($p_T>5$ GeV/$c$) in \pp and central \cucu collisions at \sNN = 200 GeV. The inclusive \Jpsi production cross section for \cucu collisions is found to be consistent at high $p_T$ with the binary collision-scaled cross section for \pp collisions, in contrast to previous measurements at lower $p_T$, where a suppression of \Jpsi production is observed relative to the expectation from binary scaling. Azimuthal correlations of $J/\psi$ with charged hadrons in \pp collisions provide an estimate of the contribution of $B$-meson decays to \Jpsi production of $13% \pm 5%$.
J/psi differential production cross section in sqrt(s).
J/psi transverse momentum distribution in sqrt(s).
J/psi transverse momentum distribution in sqrt(s).
The inclusive production cross sections of the strange vector mesons K*0, K*0bar, and phi have been measured in interactions of 920 GeV protons with C, Ti, and W targets with the HERA-B detector at the HERA storage ring. Differential cross sections as a function of rapidity and transverse momentum have been measured in the central rapidity region and for transverse momenta up to pT=3.5 GeV/c. The atomic number dependence is parametrised as sigma(pA) = sigma(pN)*A**alpha, where sigma(pN) is the proton-nucleon cross section. Within the phase space accessible, alpha(K*0) = 0.86+/-0.03, alpha(K*0bar) = 0.87+/-0.03, and alpha(phi) = 0.96+/-0.02. The total proton-nucleon cross sections, determined by extrapolating the differential measurements to full phase space, are sigma(pN->K*0) = 5.06+/-0.54 mb, sigma(pN->K*0bar) = 4.02+/-0.45 mb, and sigma(pN->phi) = 1.17+/-0.11 mb. The Cronin effect is observed for the first time for vector mesons containing strange quarks/ compared to the measurements of Cronin et al. for K+- mesons, the measured values of alpha for phi mesons coincide with those of K- mesons for all transverse momenta, while the enhancement for K*0 / K*0bar mesons is smaller.
Measured rapidity distribution for K*0 production in the accessible phase space.
Measured rapidity distribution for K*BAR0 production in the accessible phase space.
Measured rapidity distribution for PHI production in the accessible phase space.
The inclusive production of omega and phi mesons is studied in the backward region of the interaction of 12 GeV protons with polyethylene, carbon, and copper targets. The mesons are measured in e^+ e^- decay channels. The production cross sections of the mesons are presented as functions of rapidity y and transverse momentum p_T. The nuclear mass number dependences (A dependences) are found to be A^{0.710 +/- 0.021(stat) +/- 0.037(syst)} for omega mesons and A^{0.937 +/- 0.049(stat) +/- 0.018(syst)} for phi mesons in the region of 0.9 < y < 1.7 and p_T < 0.75 GeV/c.
Differential cross section as a function of rapidity (YRAP) for OMEGA production.
Differential cross section as a function of rapidity (YRAP) for PHI production.
Differential cross section as a function of transverse momentum (PT) for OMEGA production.
We report on a measurement of the inclusive cross sections of $\Lambda$ , $\overline\Lambda$ , K 0
Total inclusive hyperon production cross sections for the SIGMA- beam on the Copper target.
Total inclusive hyperon production cross sections for the SIGMA- beam on the Carbon target.
Total inclusive hyperon production cross sections per nucleon for the SIGMA- beam, and the exponent in the cross section parametrization of the form A**POWER.
Inclusive differential cross sections $d\sigma_{pA}/dx_F$ and $d\sigma_{pA}/dp_t^2$ for the production of \kzeros, \lambdazero, and \antilambda particles are measured at HERA in proton-induced reactions on C, Al, Ti, and W targets. The incident beam energy is 920 GeV, corresponding to $\sqrt {s} = 41.6$ GeV in the proton-nucleon system. The ratios of differential cross sections \rklpa and \rllpa are measured to be $6.2\pm 0.5$ and $0.66\pm 0.07$, respectively, for \xf $\approx-0.06$. No significant dependence upon the target material is observed. Within errors, the slopes of the transverse momentum distributions $d\sigma_{pA}/dp_t^2$ also show no significant dependence upon the target material. The dependence of the extrapolated total cross sections $\sigma_{pA}$ on the atomic mass $A$ of the target material is discussed, and the deduced cross sections per nucleon $\sigma_{pN}$ are compared with results obtained at other energies.
Inclusive differential cross section DSIG/DXL for K0S production in the XL interval -0.12 to 0.0 plus the total cross section after extrapolation to the full XL range.
Inclusive differential cross section DSIG/DXL for LAMBDA production in the XL interval -0.12 to 0.0 plus the total cross section after extrapolation to thefull XL range.
Inclusive differential cross section DSIG/DXL for LAMBDABAR production in the XL interval -0.12 to 0.0 plus the total cross section after extrapolation to the full XL range.
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Total inclusive production cross sections for the SIGMA- beam on the Coppertarget.
Total inclusive production cross sections for the SIGMA- beam on the Carbontarget.
Total inclusive production cross sections per nucleon for the SIGMA- beam, and the exponent in the cross section parametrization of the form A**POWER.
The production of charmed particles by Sigma- of 340 Gev/c momentum was studied in the hyperon beam experiment WA89 at the CERN-SPS, using the Omega-spectrometer. In two data-taking periods in 1993 and 1994 an integrated luminosity of 1600 microb^-1 on copper and carbon targets was recorded. From the reconstruction of 930 +- 90 charm particle decays in 10 decay channels production cross sections for D, antiD, Ds and Lambdac were determined in the region xF>0. Assuming an A^1 dependence of the cross section on the nucleon number, we calculate a total ccbar production cross section of sigma(x_F > 0) = 5.3+- 0.4(stat)+-1.0(syst)+1.0(Xi_c) microb per nucleon. The last term is an upper limit on the unknown contribution from charmed-strange baryon production.
Fits to the DSIG/DXL and DSIG/DPT**2 distributions in the range XL > 0. Theerrors shown are statistical only.. The fits are of the following form:. DSIG/DXL : Const*(1-X)**N. DSIG/DPT**2 : Const*EXP(-B*PT**2).
The production cross sections for anti-charmed and charmed hadrons in the range XL > 0. The Errors are statistical only.
The total CQUARK+CQUARKBAR cross section in the range XL > obtained as the weighted average of the sum of all the measured contributions to the charmed andanti-charmed hadron production in the previous table. second systematic (DSYS) error is due to the uncertainty in the contribution of XI/C production to the cross section.
Quasiexclusive neutral meson production in pN-interactions is studied in experiments with the SPHINX facility operating in a proton beam from the IHEP accelerator (Ep=70 GeV). The cross sections and the parameters of the differential distributions for πo, ω, η and Ko production in the deep fragmentation region (xF > 0.79 ÷ 0.86) are presented. The results show that such proton quasiexclusive reactions with baryon exchange may be promising in searches for exotic mesons.
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Data on the graph only.
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