The hadronic final states observed with the ALEPH detector at LEP in ${\rm e}^ + {\rm e}^-$ annihilation
Mean charged particle multiplicities at different c.m. energies.
XP distribution at c.m. energy 133.0 GeV.
XP distribution at c.m. energy 161.0 GeV.
Bose-Einstein correlations of identically charged pion pairs were measured by the PHENIX experiment at mid-rapidity in Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV. The Bertsch-Pratt radius parameters were determined as a function of the transverse momentum of the pair and as a function of the centrality of the collision. Using the \it{full} Coulomb correction, the ratio $R_{\rm out}/R_{\rm side}$ is smaller than unity for $<k_{\rm T}>$ from 0.25 to 1.2 GeV/c and for all measured centralities. However, using recently developed partial Coulomb correction methods, we find that $R_{\rm out}/R_{\rm side}$ is 0.8-1.1 for the measured $<k_{\rm T}>$ range, and approximately constant at unity with the number of participants.
Panel (a) and (b) show one-dimensional correlation functions for $\pi^+\pi^+$ and $\pi^-\pi^-$. The bottom figures show the three-dimensional correlation function for $\pi^-\pi^-$ with the full Coulomb (open circle) and without Coulomb (filled triangle) corrections for 0.2 < $k_T$ < 2.0 GeV/$c$ for 0-30% centrality. The projection of the 3-D correlation functions are averaged over the lowest 40 MeV in the orthogonal directions. The error bars are statistical only. The lines overlaid on the open circles (filled triangles) correspond to fits to Eq. 1 (Eq. 2) over the entire distribution. Panel (c) shows the one-dimensional correlation function of unlike-signed pions for 0.2 < $k_T$ < 2.0 GeV/$c$. The two overlaid histograms show calculations for the full (dashed) and the 50% partial (solid) Coulomb corrections. $<k_T>$ ~ 0.45 ($\pm$0.17) GeV/$c$ and $<N_{part}>$ ~ 281 ($\pm$4).
The $k_T$ dependence of the Bertsch-Pratt radius parameters and $\lambda$ for charged pions for 0-30% centrality. Filled triangles show the results from fits to a core-halo structure by Eq. 2, with statistical error bars and systematic error bands. Open circles and squares show the results from the full (Eq. 1) and 50% partial (Eq. 3) Coulomb corrections with statistical error bars, respectively. Results at 130 GeV by PHENIX are given by filled circles.
The $k_T$ dependence of the Bertsch-Pratt radius parameters and $\lambda$ for charged pions for 0-30% centrality. Filled triangles show the results from fits to a core-halo structure by Eq. 2, with statistical error bars and systematic error bands. Open circles and squares show the results from the full (Eq. 1) and 50% partial (Eq. 3) Coulomb corrections with statistical error bars, respectively. Results at 130 GeV by PHENIX are given by filled circles.
We present a measurement of the double longitudinal spin asymmetry in inclusive pi^0 production in polarized proton-proton collisions at sqrt(s)=200 GeV. The data were taken at the Relativistic Heavy Ion Collider with average beam polarizations of 26%. The measurements are the first of a program to study the longitudinal spin structure of the proton, using strongly interacting probes, at collider energies. The asymmetry is presented for transverse momenta 1-5 GeV/c at mid-rapidity, where next-to-leading order perturbative quantum chromodynamic (NLO pQCD) calculations describe the unpolarized cross section well. The observed asymmetry is small and is compared with a NLO pQCD calculation with a range of polarized gluon distributions.
Double spin asymmetry for the raw signal ($\pi^0 + BG$), for the background ($BG$) and for $\pi^0$ background corrected; single spin asymmetry for $\pi^0$ background corrected; for the four $p_T$ bins.
Single spin raw asymmetry normalized by the beam polarization, $\epsilon$/$P$, as a function of azimuthal angle $\phi$, for forward neutron production.
The measured double spin asymmetry $A^{\pi^0}_{LL}$ versus mean $p_T$ of $\pi^0$s in each bin. Not included in the figure/table: the correlated for all points scale systematic uncertainty of 65% (scales values and stat. uncertainties of points by the same factor).
The W + W- production cross section is measured from a data sample corresponding to a total integrated luminosity of 683 pb-1, collected by the ALEPH experiment at LEP at centre-of-mass energies from
The measured cross section for the E NU E NU final state. The DSYS error is the typical systematic error.
The measured cross section for the E NU MU NU final state. The DSYS error is the typical systematic error.
The measured cross section for the E NU TAU NU final state. The DSYS error is the typical systematic error.
The production of deuterons and antideuterons in the transverse momentum range 1.1 < p_T < 4.3 GeV/c at mid-rapidity in Au + Au collisions at sqrt(s_NN)=200 GeV has been studied by the PHENIX experiment at RHIC. A coalescence analysis comparing the deuteron and antideuteron spectra with those of protons and antiprotons, has been performed. The coalescence probability is equal for both deuterons and antideuterons and increases as a function of p_T, which is consistent with an expanding collision zone. Comparing (anti)proton yields p_bar/p = 0.73 +/- 0.01, with (anti)deuteron yields: d_bar/d = 0.47 +/- 0.03, we estimate that n_bar/n = 0.64 +/- 0.04.
Corrected spectra for deuterons and anti-deuterons for different centralities are plotted vs $m_T$.
Corrected spectra for deuterons and anti-deuterons for different centralities are plotted vs $m_T$.
Coalescence parameter $B_2$ vs $p_T$ for deuterons (left panel) and anti-deuterons (right panel). Grey bands indicate the systematic errors. Values are plotted at the "true" mean value of $p_T$ of each bin, the extent of which is indicated by the width of the grey bars along x-axis.
The cross sections for single vector boson production in the We ν and Zee channels are measured from the data collected by the ALEPH detector at LEP for centre-of-mass energies between 183 and 209 GeV. These data correspond to a total integratedluminosity of 683 pb −1 . Single-W production is studied in both hadronic and leptonic decay channels. Hadronic and dimuon decays are used for single-Z production. The measured cross sections agree with the Standard Model predictions.
Measured cross sections for single W production in the leptonic and hadronic decay channels of the W separately and combined.
The measured single Z0 production cross section.
Z0 --> MU+ MU- cross section averaged over all c.m. energies.
The process e+e- --> pi+ pi- pi0 gamma has been studied at a center-of-mass energy near the Y(4S) resonance using a 89.3 fb-1 data sample collected with the BaBar detector at the PEP-II collider. From the measured 3pi mass spectrum we have obtained the products of branching fractions for the omega and phi mesons, B(omega --> e+e-)B(omega --> 3pi)=(6.70 +/- 0.06 +/- 0.27)10-5 and B(phi --> e+e-)B(phi --> 3pi)=(4.30 +/- 0.08 +/- 0.21)10-5, and evaluated the e+e- --> pi+ pi- pi0 cross section for the e+e- center-of-mass energy range 1.05 to 3.00 GeV. About 900 e+e- --> J/psi gamma --> pi+ pi- pi0 gamma events have been selected and the branching fraction B(J/psi --> pi+ pi- pi0)=(2.18 +/- 0.19)% has been measured.
The measured 3PI mass spectrum calculated for a 25 MeV bin size.
Two particle correlations between identified meson and baryon trigger particles with 2.5 < p_T < 4.0 GeV/c and lower p_T charged hadrons have been measured at midrapidity by the PHENIX experiment at RHIC in p+p, d+Au and Au+Au collisions at sqrt(s_NN) = 200 GeV. The probability of finding a hadron near in azimuthal angle to the trigger particle is almost identical for leading mesons and baryons for non-central Au+Au. The yield for both trigger baryons and mesons is significantly higher in Au+Au than in p+p and d+Au, except for trigger baryons in central collisions. The baryon excess is likely to arise predominantly from hard scattering processes.
$\Delta\phi$ distributions for meson and baryon triggers with 2.5 < $p_T$ < 4.0 GeV/$c$ and associated charged hadrons with 1.7 < $p_T$ < 2.5 GeV/$c$ for five centralities in Au+Au collisions.
$\Delta\phi$ distributions for meson triggers with 2.5 < $p_T$ < 4.0 GeV/$c$ and associated charged hadrons with 1.7 < $p_T$ < 2.5 GeV/$c$ in $d$+Au collisions.
$\Delta\phi$ distributions unidentified triggers with 2.5 < $p_T$ < 4.0 GeV/$c$ and associated charged hadrons with 1.7 < $p_T$ < 2.5 GeV/$c$ in $p$+$p$ collisions.
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 PHENIX experiment at RHIC has measured transverse energy and charged particle multiplicity at mid-rapidity in Au+Au collisions at sqrt(s_NN) = 19.6, 130 and 200 GeV as a function of centrality. The presented results are compared to measurements from other RHIC experiments, and experiments at lower energies. The sqrt(s_NN) dependence of dE_T/deta and dN_ch/deta per pair of participants is consistent with logarithmic scaling for the most central events. The centrality dependence of dE_T/deta and dN_ch/deta is similar at all measured incident energies. At RHIC energies the ratio of transverse energy per charged particle was found independent of centrality and growing slowly with sqrt(s_NN). A survey of comparisons between the data and available theoretical models is also presented.
$B$/$A$ ratio from the fit to the data.
$B$/$A$ ratio from the fit to the data.
Parameter $\alpha$ from the fit to the data.
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