Results are presented from a study of the structure of high energy hadronic events recorded by the L3 detector at sqrt(s)>192 GeV. The distributions of several event shape variables are compared to resummed O(alphaS^2) QCD calculations. We determine the strong coupling constant at three average centre-of-mass energies: 194.4, 200.2 and 206.2 GeV. These measurements, combined with previous L3 measurements at lower energies, demonstrate the running of alphaS as expected in QCD and yield alphaS(mZ) = 0.1227 +- 0.0012 +- 0.0058, where the first uncertainty is experimental and the second is theoretical.
The measured ALPHA_S at three centre-of-mass energies from fits to the individual event shape distributions. The first error is statistcal, the first DSYS error is the experimental systematic uncertainty, and the second DSYS error is the theoryuncertainty.
Updated ALPHA_S measurements from the BT, BW and C-Parameter distributions,from earlier L3 data at lower centre-of-mass energies.. The first error is the total experimental error (stat+sys in quadrature) and the DSYS error is the theory uncertainty.
Combined ALPHA_S values from the five event shape variables. The first error is statistical, the first DSYS error is the experimental systematic uncertainity, the second DSYS error is the uncertainty from the hadronisdation models, andthethird DSYS errpr is the uncertainty due to uncalculated higher orders in the QCDpredictions.
We have reconstructed the radiative decays $\chi_{b}(1P) \to \Upsilon(1S) \gamma $ and $\chi_{b}(2P) \to \Upsilon(1S) \gamma $ in $p \bar{p}$ collisions at $\sqrt{s} = 1.8$ TeV, and measured the fraction of $\Upsilon(1S)$ mesons that originate from these decays. For $\Upsilon(1S)$ mesons with $p^{\Upsilon}_{T}>8.0$ GeV/$c$, the fractions that come from $\chi_{b}(1P)$ and $\chi_{b}(2P)$ decays are $(27.1\pm6.9(stat)\pm4.4(sys))%$ and $(10.5\pm4.4(stat)\pm1.4(sys))%$, respectively. We have derived the fraction of directly produced $\Upsilon(1S)$ mesons to be $(50.9\pm8.2(stat)\pm9.0(sys))%$.
No description provided.
We present a measurement of the forward-backward charge asymmetry of the process pp¯→Z0/γ+X,Z0/γ→e+e− at Mee>MZ, using 110pb−1 of data at s=1.8TeV collected at the Collider Detector at Fermilab. The measured charge asymmetries are 0.43±0.10 in the invariant mass region Mee>105GeV/c2, and 0.070±0.016 in the region 75<Mee<105GeV/c2. These results are consistent with the standard model values of 0.528±0.009 and 0.052±0.002, respectively.
The forward-backward asymmetry resuts from angular differential cross section : D(SIG)/D(COS(THETA*) = A*(1 + COS(THETA*)**2) + B*COS(THETA*), where THETA * is the emission angle of the E- relative to the quark momentum in the rest frame of the E+ E- pair.
Short overview of experiments with SND detector at VEPP-2M e^+e^- collider in the energy range 2E = 400 - 1400 MeV and preliminary results of data analysis are presented.
No description provided.
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Using the Mark-J detector at the high-energy e+e− collider PETRA, we compare the data from hadron production with the complete second-order QCD calculation over the energy region 22 to 46.78 GeV. We determine the QCD parameter Λ=100±30−45+60 MeV which yields the strong-coupling constant αs=0.12±0.02 for s=44 GeV.
No description provided.
Axis error includes +- 0.0/0.0 contribution (DUE TO FRAGMENTATION MODEL).
The yields and average transverse momenta of pions, kaons, and antiprotons produced at the Fermilab p¯p collider at s=300, 540, 1000, and 1800 GeV are presented and compared with data from the energies reached at the CERN collider. We also present data on the dependence of average transverse momentum 〈pt〉 and particle ratios as a function of charged particle density dNcdη; data for particle densities as high as six times the average value, corresponding to a Bjorken energy density 6 GeV/fm3, are reported. These data are relevant to the search for quark-gluon phase of QCD.
PT RANGE FROM 0 TO INFINITY.
PT RANGE FROM 0 TO INFINITY.
No description provided.
The reaction e + e − → τ + τ − has been studied at centre of mass energies between 14.0 and 46.8 GeV with the CELLO detector at the PETRA e + e − collider. We present results for the cross section σ τ and the charge asymmetry A τ . The results are in good agreement with the standard model. We have also measured the topological decay rates BR 1 , BR 3 and BR 5 for the inclusive decay of the τ lepton into one, three and five charge particles. The results confirm and improve earlier CELLO measurements at other energies. We find for the combined values at all energies BR 1 = (84.9 ± 0.4 ± 0.3)%, BR 3 = (15.0 ± 0.4 ± 0.3)% and BR 5 = (0.16 ± 0.13 ± 0.04)%.
No description provided.
No description provided.
Corrected for radiative effects and background contributions.
Measurements of the total cross section have been performed at the ISR with c.m. energies between 23.5 GeV and 62.5 GeV. Two independent experimental methods have been applied, a measurement of total interaction rate and of small angle elastic scattering. Both experiments give consistent results showing that the total cross section increases by (11.8±1.5) % over the ISR energy range. This experiment has also measured the slope of the forward diffraction peak in elastic scattering at small momentum transfer. The elastic cross section shows the same relative rise as the total cross section, and the ratio λ of elastic to total cross section approaches a constant value of λ =0.178±0.003.
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TOTAL CROSS SECTION FROM (INTERACTION RATE)/(LUMINOSITY). SYSTEMATIC ERROR <0.8 PCT.
TOTAL CROSS SECTION FROM APPLYING THE OPTICAL THEOREM TO SMALL ANGLE ELASTIC SCATTERING EXTRAPOLATED TO T=0.
We report on the experimental results obtained at the ISR for the η particle production at 90° and √ s = 30.6 and 53.2 GeV. We determine the invariant cross section and the p t distribution in the interval 1 ⩽ p t ⩽ 5 GeV/ c . We find that the p t distribution has the same shape of the π 0 production and differ from it by a constant factor R 90° = 0.5 ± 0.07.
No description provided.
The inclusive production of ϱ 0 mesons in pp collisions has been measured at five c.m. energies from √ s = 23.6 to 63.0 GeV. The cross sections and the production spectra as a function of transverse momentum and rapidity are discussed.
No description provided.
No description provided.
The measurement of the proton-proton total cross section performed by the CERN-Pisa-Rome-Stony Brook Collaboration at the CERN ISR is discussed in detail. The total interaction rate, the elastic scattering rate in the forward direction, and the machine luminosity were measured simultaneously to obtain three different determinations of the total cross section. Consistent results were found, which made it possible to prove the reliability of the Van der Meer luminosity calibration within +-0.9% and to achieve a precision of +-0.6% in the measurement of the total cross section.
No description provided.
We present the results of a systematic analysis of charge-exchange double dissociation in proton-proton collisions at the CERN Intersecting Storage Rings. The data, obtained with the Split-Field Magnet detector, cover the entire ISR energy range between s = 23 GeV and s = 63 GeV at five standard energies.
CHARGE EXCHANGE DOUBLE DIFFRACTION DISSOCIATION OF PROTONS. THESE CROSS SECTIONS WERE REPORTED IN G. GOGGI ET AL., PL 72B, 265 (1977).
No description provided.
THE SEMI INCLUSIVE DENSITY MATRICES ARE ALSO GIVEN (P P --> DEL++ P PI- + DEL0 P PI+).
Measurements of the double differential cross sections for ππ and pπ production in pp collisions at the CERN ISR are presented for 5 c.m. energies s = 22, 30, 44, 53, 62 GeV . Charge and transverse momentum correlations are also reported.
No description provided.
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The acceptance-corrected dielectron excess mass spectra, where the known hadronic sources have been subtracted from the inclusive dielectron mass spectra, are reported for the first time at mid-rapidity $|y_{ee}|<1$ in minimum-bias Au+Au collisions at $\sqrt{s_{NN}}$ = 19.6 and 200 GeV. The excess mass spectra are consistently described by a model calculation with a broadened $\rho$ spectral function for $M_{ee}<1.1$ GeV/$c^{2}$. The integrated dielectron excess yield at $\sqrt{s_{NN}}$ = 19.6 GeV for $0.4<M_{ee}<0.75$ GeV/$c^2$, normalized to the charged particle multiplicity at mid-rapidity, has a value similar to that in In+In collisions at $\sqrt{s_{NN}}$ = 17.3 GeV. For $\sqrt{s_{NN}}$ = 200 GeV, the normalized excess yield in central collisions is higher than that at $\sqrt{s_{NN}}$ = 17.3 GeV and increases from peripheral to central collisions. These measurements indicate that the lifetime of the hot, dense medium created in central Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV is longer than those in peripheral collisions and at lower energies.
Reconstructed dielectron unlike-sign pairs, like-sign pairs and signal distributions, together with the signal to background ratio (S/B). All columns are presented as a function of dielectron invariant mass in Au+Au collisions at $\sqrt{s_{NN}}$ = 19.6 GeV.
Dielectron invariant mass spectrum in the STAR acceptance (|$y_{ee}$| < 1, 0.2 < $p_T^e$ < 3 GeV/c, |$\eta^e$ | < 1) after efficiency correction in Au+Au collisions at $\sqrt{s_{NN}}$ = 19.6 GeV.
Hadronic cocktail consisting of the decays of light hadrons and correlated decays of charm in Au+Au collisions at $\sqrt{s_{NN}}$ = 19.6 GeV.
A search for the quantum chromodynamics (QCD) critical point was performed by the STAR experiment at the Relativistic Heavy Ion Collider, using dynamical fluctuations of unlike particle pairs. Heavy-ion collisions were studied over a large range of collision energies with homogeneous acceptance and excellent particle identification, covering a significant range in the QCD phase diagram where a critical point may be located. Dynamical $K\pi$, $p\pi$, and $Kp$ fluctuations as measured by the STAR experiment in central 0-5\% Au+Au collisions from center-of-mass collision energies $\rm \sqrt{s_{NN}}$ = 7.7 to 200 GeV are presented. The observable $\rm \nu_{dyn}$ was used to quantify the magnitude of the dynamical fluctuations in event-by-event measurements of the $K\pi$, $p\pi$, and $Kp$ pairs. The energy dependences of these fluctuations from central 0-5\% Au+Au collisions all demonstrate a smooth evolution with collision energy.
$p\pi$, Kp, and $K\pi$ fluctuations as a function of collision energy, expressed as $v_{dyn,p\pi}$, $v_{dyn,Kp}$, and $v_{dyn,K\pi}$ respectively. Shown are data from central (0-5%) Au+Au collisions at energies from $\sqrt{s_{\rm NN}}$ = 7.7 to 200 GeV from the STAR experiment.
We present results from a harmonic decomposition of two-particle azimuthal correlations measured with the STAR detector in Au+Au collisions for energies ranging from $\sqrt{s_{NN}}=7.7$ GeV to 200 GeV. The third harmonic $v_3^2\{2\}=\langle \cos3(\phi_1-\phi_2)\rangle$, where $\phi_1-\phi_2$ is the angular difference in azimuth, is studied as a function of the pseudorapidity difference between particle pairs $\Delta\eta = \eta_1-\eta_2$. Non-zero {\vthree} is directly related to the previously observed large-$\Delta\eta$ narrow-$\Delta\phi$ ridge correlations and has been shown in models to be sensitive to the existence of a low viscosity Quark Gluon Plasma (QGP) phase. For sufficiently central collisions, $v_3^2\{2\}$ persist down to an energy of 7.7 GeV suggesting that QGP may be created even in these low energy collisions. In peripheral collisions at these low energies however, $v_3^2\{2\}$ is consistent with zero. When scaled by pseudorapidity density of charged particle multiplicity per participating nucleon pair, $v_3^2\{2\}$ for central collisions shows a minimum near {\snn}$=20$ GeV.
Representative results on $v_3^2\{2\}$ from Au+Au collisions as a function of $\Delta\eta$ for charged hadrons with pT > 0.2 GeV/c and |$\eta$| < 1.
Representative results on $v_3^2\{2\}$ from Au+Au collisions as a function of $\Delta\eta$ for charged hadrons with pT > 0.2 GeV/c and |$\eta$| < 1.
Representative results on $v_3^2\{2\}$ from Au+Au collisions as a function of $\Delta\eta$ for charged hadrons with pT > 0.2 GeV/c and |$\eta$| < 1.
None
No description provided.
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The average charged multiplicity in proton-proton interactions has been studied at √ s = 62 GeV. A very good agreement with the average charged multiplicity measured in e + e − annihilation at different energies is obtained by redefining, in p-p, the correct energies available for particle production. This means that a p-p collision at √ s = 62 GeV does in fact correspond to a large range of effective hadronic energies available for particle production.
AVERAGE CHARGED MULTIPLICITY AS A FUNCTION OF HADRONIC ENERGY WHERE E(NAME=HAD) IS THE INCIDENT PROTON ENERGY (COLLIDING BEAM ENERGY) MINUS THE LEADING PROTON ENERGY.
We report results on a new measurement of the double diffractive reaction pp → (p π + π − ) (p π + π − ) at the ISR obtained with the Split Field Magnet detector. Experimental procedures and data analysis are discussed in detail. The cross section measured at the five standard ISR energies exhibits an increase of (55 ± 7)% in the s -range from 549 to 3892 GeV 2 .
DOUBLE DIFFRACTION DISSOCIATION OF PROTONS.
Measurements of the cross section for the production of electron pairs with invariant masses between 4 and 8.7 GeV are presented as a function of the centre-of-mass energy ( s = 28 to s = 62 GeV ) of the colliding proton beams. A significant excess of events is observed in the region 8.7 to 10.3 GeV; these are ascribed to the ϒ(9.5 GeV) resonances and estimates of the production cross sections are given.
Axis error includes +- 40/40 contribution (Due to the uncertainty in efficiency).
Axis error includes +- 40/40 contribution (Due to the uncertainty in efficiency).
We have measured the charge-exchange reaction pp → (p π + ) (p π − ) at s = 23, 31, 45, 53, and 63 GeV at the ISR, using the Split Field Magnet detector. The data are characterized by a sharp forward peak of width 0.02 (GeV/ c ) 2 , followed by a much gentler slope at higher | t |; sizeable Δ ++ , Δ 0 , and N 0 production is observed in the (Nπ) mass spectra. Two different components are present in the data following power-law energy dependence of the type p lab − n with n 1 = −1.63 ± 0.13 and n 2 = −0.96 ± 0.07, respectively, indicating the onset of mechanisms in competition with pion exchange at ISR energies.
CHARGE EXCHANGE DOUBLE DIFFRACTION DISSOCIATION OF PROTONS. DEL++, DEL0, N(1520)0 AND N(1688)0 RESONANCES IDENTIFIED IN PROTON-PION MASS SPECTRA.
We report on a study of the charge-exchange reaction pp → nΔ ++ (1232) at the CERN intersecting storage rings (ISR) in the energy range √ s = 23 to 53 GeV. From our analysis of the energy dependence of the total cross-section, of the differential cross-section d σ /d t and of the decay angular distributions we find evidence that pion exchange is dominant up to √ s = 23 GeV and that ( ϱ +A 2 ) exchange dominates the reaction for √ s ⩾ 30 GeV, as described by simple Regge-pole models.
THE ERRORS ARE DUE TO STATISTICAL ERRORS AND BACKGROUND SUBTRACTION ERRORS COMBINED IN QUADRATURE.
THE ERRORS ARE DUE TO STATISTICAL ERRORS AND BACKGROUND SUBTRACTION ERRORS COMBINED IN QUADRATURE.
No description provided.
We have measured direct photon production in pp collisions at the CERN intersecting storage rings for c.m. energies 31 < √ s < 63 GeV and transverse momenta up to 9GeV/ c , using segmented lead/liquid-argon calorimeters. The ratio of direct photon to π 0 production is significantly larger than zero, starting at p T ≈ 4 GeV/ c and increasing to values of about 0.4 at 9GeV/ c . No significant √s dependence is seen.
No description provided.
We present the B( d θ d y ) y=0 for J /ψ over thefull range of ISR energies and for ϒ at √ s = 53 and 63 GeV, using their dielectron decay mode. The average transverse momentum and the decay angles are presented. We found ( p T ) = 1.75 ± 0.19 GeV for ϒ, being higher than ( p T ) of the continuum and rising with √s. We present a comparison of the cross sections of J/ψ and ϒ with those of the continuum, at the same masses, as a function of √s. An appropriate scaling of the hadronic production of quark-antiquark narrow bound states involving ⋉, J/ψ, ψ′, ϒ, and ϒ′ is presented as a function of m /√ s at y = 0, and is compared with Drell-Yan scaling.
No description provided.
UPSILON HERE = UPSILON+UPSILON PRIME.
The inclusive η production cross section at the CERN ISR has been measured for p T values of up to 11 GeV/ c . We find that the η π 0 cross-section ratio has an average value of 0.55 ± 0.07 and varies little with p T .
No description provided.
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