Using the ARGUS detector at DORIS II, we have studied the production of the charmed baryon Λ c in e + e − annihilation at centre-of-mass energies near 10 GeV. The Λ c + was seen in the three decay modes pK − π + , Λπ + π − π + and K̄ 0 p, with products of normalized cross section times branching ratio [ R ·Br] of (10.8±1.4±1.2)×10 −3 , 6.6±1.5±0.9)×10 −3 and (6.7±1.4±0.8)×10 −3 respectively. The measured mass for the Λ c was (2283.1±1.7±2.0) MeV/ c 2 . A limit on the decay rates to Λπ + is reported. The fragmentation function of the Λ c was measured.
No description provided.
We present an analysis of the K ππ system produced in 10 GeV/ c K + p interactions. We show that the low-mass enchancement between 1.2 and 1.4 GeV/ c 2 on the K ππ mass spectrum is predominantly 1 + throughout, give the relative amplitudes for the decay of this system into K ∗ (890) π and K ρ , and offer new evidence for the presence of two 1 + resonances in this mass region.
No description provided.
DIFFERENTIAL CROSS SECTION FOR THREE MASS BANDS IN Q-REGION. NORMALIZATION UNCERTAIN - NO UNITS FOR D(SIG)/DT GIVEN ON FIGURE. NUMERICAL VALUES TAKEN FROM THE COMPILATION LST7V2 FOX 72B. ERRORS ADDED AS 1/SQRT(EVENTS).
The JETSET (PS202) experiment at CERN-LEAR searches for hadronic resonances by means of in-flight antiproton-proton annihilations in the reaction p p → φφ . In order to obtain sufficient luminosity and good final-state mass resolution, this experiment uses an internal hydrogen-cluster jet target intersecting the LEAR antiproton beam. We report on the study of the reaction p p → 4K ± at 1.4 GeV / c incident p̄ momentum, and we present the first experimental observation of a stro φφ signal in this reaction.
No description provided.
No description provided.
The final states K S 0 K S 0 π + π − and K S 0 K ∓ π 0 π ± , produced in two-photon reactions, have been studied using the ARGUS detector at the e + e − storage ring DORIS II at DESY. The reaction γγ→ K ∗+ K ∗− has been observed for the first time. Its cross section is about eight times larger than that for γγ→ K ∗0 K ∗0 , but it has a similar W γγ dependence.
No description provided.
Topological cross section.
Topological cross section.
Using the ARGUS detector at the e + e - storage ring DORIS II at DESY, we have observed the decay D s + → η'π + in two decay modes of the η'. We measure the ratio of branching ratios BR(D s + → η'π + )/BR(D s + → Øπ + ) to be 2.5±0.5±0.3.
The cross section times Br(D/S+ --> ETAPRIME PI+), but is not included the ETAPRIME branching ratio.
We study the processes $e^+ e^-\to K^+ K^- \pi^+\pi^-\gamma$, $K^+K^-\pi^0\pi^0\gamma$ and $K^+ K^- K^+ K^-\gamma$, where the photon is radiated from the initial state. About 34600, 4400 and 2300 fully reconstructed events, respectively, are selected from 232 \invfb of \babar data. The invariant mass of the hadronic final state defines the effective \epem center-of-mass energy, so that the $K^+ K^- \pi^+\pi^-\gamma$ data can be compared with direct measurements of the $e^+ e^-\to K^+K^- \pipi$ reaction/ no direct measurements exist for the $e^+ e^-\to K^+ K^- \pi^0\pi^0$ or $\epem\to K^+ K^- K^+ K^-$ reactions. Studying the structure of these events, we find contributions from a number of intermediate states, and we extract their cross sections where possible. In particular, we isolate the contribution from $e^+ e^-\to\phi(1020) f_{0}(980)$ and study its structure near threshold. In the charmonium region, we observe the $J/\psi$ in all three final states and several intermediate states, as well as the $\psi(2S)$ in some modes, and measure the corresponding branching fractions. We see no signal for the Y(4260) and obtain an upper limit of $\BR_{Y(4260)\to\phi\pi^+\pi^-}\cdot\Gamma^{Y}_{ee}<0.4 \ev$ at 90% C.L.
Measurement of the E+ E- --> K+ K- PI+ PI- cross section. Statistical errors only.
Measurement of the E+ E- --> K(892)0 K PI cross section. Statistical errors only.
Measurement of the E+ E- --> PHI PI+ PI- cross section. Statistical errors only.
The final state K + K − π + π − has been studied in γγ interactions using the ARGUS detector at the e + e − storage ring DORIS II at DESY. Production of the vector meson pair K ∗0 (892) K ∗0 (892) is observed for the first time. The cross section for K + K − π + π − , K ∗0 K − π + +c.c. and K ∗0 K ∗0 are all found to be of the order of a few nb. In the W γγ range accessible, a mean upper limit of 0.5 nb at 95% CL is derived for φϱ 0 production.
TOPOLOGICAL CROSS SECTION.
(K*0 K*BAR0) cross section.
(K*0 K- PI+ + CC) CROSS SECTION WITH (K*0 K*BAR0) REMOVED.
The reaction γγ→K + K − π + π − π 0 has been observed for the first time, using the ARGUS detector at the e + e − storage ring DORIS II at DESY. The cross section shows an enhancement for W γγ close to 3 GeV/ c 2 . Searches for γγ→ωφ and for γγ→φφ leading to this final state, as well as for γγ→φφ→2K + 2K − , have been performed. The derived upper limits for ωφ and φφ production are compatible with q q q q model predictions.
TOPOLOGICAL CROSS SECTION.
95 PCT CL UPPER LIMITS.
The π − p→K 0 λ polarization has been measured at 5 GeV/ c in the range 0<− t <1.4 (GeV/ c ) 2 . The polarization is small for − t ⪅0.4 (GeV/ c ) 2 , becoming negative at the higher values of − t .
No description provided.
Using the ARGUS detector at the e + e − storage ring DORIS II at DESY, we have found evidence for the production of the excited charmed baryon state Λ c (2593) + in the channel Λ c + π + π − . Its mass was determined to be (2594.6±0.9±0.4) MeV/c 2 , and the natural width measured to be Γ = (2.9 −2.1−1.4 +2.9+1.8 ) MeV. The production cross section times the branching ratios of σ ( e + e − → Λ c (2593) + X ) × Br ( Λ c (2593) + → Λ c + π + π − ) × Br ( Λ c + → pK − π + ) was measured to be (0.25 −0.13 +0.24 ±0.13) pb. The fractions of Λ c (2593) + decays proceeding through the Σ c 0 π + and Σ c ++ π − channels were determined to be 0.29±0.10±0.11 and 0.37±0.12±0.13, respectively.
Results with and without extrapolation.
A sample of about 1.4 million hadronic Z decays, selected among the data recorded by the DELPHI detector at LEP during 1994, was used to measure for the first time the momentum spectra of K + , K 0 , p , Λ and their antiparticles in gluon and quark jets. As observed for inclusive charged particles, the production spectra of identified particles were found to be softer in gluon jets than in quark jets, with a higher total multiplicity.
Y events.
Mercedes events.
We report the first observation of an orbitally excited baryon, the Λ(1520), in quark and gluon fragmentation. The production rate is found to be (1.15±0.21±0.16)×10 −2 and (0.80±0.17 −0.13 +0.10 )×10 −2 Λ (1520) hyperons per event in direct ϒ decays and in the continuum, respectively. In contrast to the observed situation for ground state baryons, the production of the Λ(1520) in direct ϒ decays shows little or no enhancement with respect to continuum production.
Full X range uses extrapolation from fit to dsig/dz distribution.
No description provided.
UPSI(1S) DECAYS.
Using the ARGUS detector at DORIS, we observe the production of D ∗+ s mesons in e + e − annihilation through their subsequent decays to a D + s and a photon. Photons which convert in the beam pipe or drift chamber inner wall are used to obtain a high precision measurement of the D ∗+ s -D + s mass difference, while photons detected in the shower counters are used to determine the production cross section, and to provide an independent measurement of the D ∗+ s -D + s mass difference. The observed D ∗+ s - D + s mass difference is 142.5±0.8±1.5 MeV/ c 2 , and σ(e + e − →D ∗+ s X)·BR(D ∗+ s →D + s γ)(·BR(D + s →φπ + ) is 4.4±1.1±1.0 pb at 10.2 GeV. The width of the D ∗+ s is less than 4.5 MeV/ c 2 at 90% confidence level.
Cross sections uncorrected for branching ratios.
Measurements of inclusive transverse-momentum spectra for KS0 mesons produced in proton-antiproton collisions at s of 630 and 1800 GeV are presented and compared with data taken at lower energies. The ratio, as a function of pT, of the cross section for KS0 to that for charged hadrons is very similar to what is observed at lower energies. At 1800 GeV, we calculate the strangeness-suppression factor λ=0.40±0.05.
Estimated effective cross sections for events which pass the trigger and selection criteria. The uncertainties in these represent the principal source of error in the overall normalisation of the results.
Statistical errors only.
Statistical errors only.
The production cross sections for the Λ, Σ0, Ξ−, Σ0 (1385), Ξ0 (1530) and Ω− hyperons have been measured, both in the continuum and in direct ϒ decays. Baryon rates in direct ϒ decays are enhanced by a factor of 2.5 or more compared to the continuum. Such a large baryon enhancement cannot be explained by standard fragmentation models. The strangeness suppression for baryons and mesons turns out to be the same. A strong suppression of spin 3/2 states is observed.
Hyperon rates per multihadronic event in direct UPSILON decays.
Hyperon rates per multihadronic event in the continuum.
LAMBDA spectrum (1/SIG(had))*D(SIG)/D(X) for UPSILON (1S) direct decays, with X = P/Pmax.
Using the ARGUS detector at the DORIS II e + e − storage ring at DESY, we have obtained evidence for a new charmed-strange meson which decays into D *+ K 0 . Its mass is observed to be 2535.9±0.6±2.0 MeV/ c 2 and its width to be less than 4.6 MeV/ c 2 at the 90% confidence level. No structure is observed at this mass in the D + K 0 invariant mass spectrum, which suggests that an unnatural spin-parity is preferred.
No description provided.
A high-mass Δ resonance is observed in several final states from π + p interactions at 10.3 GeV/ c . We obtain fitted mass and width values for this structure of 1871 ± 22 MeV and 205 ± 43 MeV, respectively. The branching ratios for decays to π + p, p π + π 0 , n π + π + and Σ + K + are found to be 0.48 ± 0.15, 0.26 ± 0.07, 0.24 ± 0.07 and 0.03 ± 0.01, respectively. The Δϱ, Δω differential cross sections and the ϱ 0 density matrix elements are examined.
DEL(1950B) (OR DEL(1880B)) FITTED WITH BRIET-WIGNER RESONANCE AND POLYNOMIAL BACKGROUND.
A partial-wave analysis of the K 0 π + π − system from the reaction K − p → K 0 π + π − n has been carried out using data obtained at 8.25 GeV/ c in a high-statistics experiment. A strong signal appears in the 1 + SO + (K ∗ π) wave at the Q 2 mass (≈ 1.4 GeV). The 1 + S0 + (ϱK) wave behaves rather like a background and does not exhibit the characteristics of a resonance. A prominent signal also appears in the 2 + D wave (via K ∗ π and ϱK); it is interpreted as the K ∗ (1430). In the L region (1.6–2.1) GeV, there is evidence for the 3 − K ∗ (1780) while the 2 − wave also gives some contribution.
FULLY CORRECTED CROSS SECTION.
RESONANCE FITS CROSS SECTIONS USING BREIT WIGNER FUNCTION. NOTE THAT FOR THE K*(1780) THE CROSS SECTION DETERMINATION IS STRONGLY DEPENDENT ON THE BACKGROUND ASSUMED WHICH HAS BEEN ONLY SUBTRACTED AT 8.25 GEV.
Results on hyperon production are reported for data accumulated at 10 GeV centre-of-mass energy with the ARGUS detector. Signals for both the octet states Λ, Σ 0 and Ξ − and the decuplet states Σ ± (1385), Ξ 0 (1530) and Ω − are observed 1 (references to a specific state are to be interpreted as also implying the charge conjugate state), some for the first time in e + e − annihilation. Baryon rates from γ dir (1S) decays are enhanced by a factor of about 3 over the continuum.
No description provided.
No description provided.
Using the CLEO-c detector at the Cornell Electron Storage Ring, we have measured inclusive and exclusive cross sections for the production of D+, D0 and Ds+ mesons in e+e- annihilations at thirteen center-of-mass energies between 3.97 and 4.26 GeV. Exclusive cross sections are presented for final states consisting of two charm mesons (DD, D*D, D*D*, Ds+Ds-, Ds*+Ds-, and Ds*+Ds*-) and for processes in which the charm-meson pair is accompanied by a pion. No enhancement in any final state is observed at the energy of the Y(4260).
Exclusive cross section for two body neutral non-strange charm mesons.
Exclusive cross section for two body charged non-strange charm mesons.
Exclusive cross section for two body strange charm mesons.
We describe a search for psi(3770) decay to two-body non-DDbar final states in e+e- data produced by the CESR collider and analyzed with the CLEO-c detector. Vector-pseudoscalar production of Rho0Pi0, Rho+Pi-, OmegaPi0, PhiPi0, RhoEta, OmegaEta, PhiEta, RhoEtaPrime, OmegaEtaPrime, PhiEtaPrime, Kstar0 K0bar, and Kstar+K- is studied along with that of BOnePi (BOne0Pi0 and BOne+Pi-) and Pi+Pi-Pi0. A statistically significant signal is found for PhiEta, at an excess cross section of (2.4 +- 0.6) pb [Gamma_{PhiEta} (psi(3770)) =(74 +- 16)Mev], and a suggestive suppression of Pi+Pi-Pi0 and RhoPi. We conclude with form factor determinations for OmegaPi0, RhoEta, and RhoEtaPrime.
Cross sections at 3.671 and 3.773 GeV.
Results are presented on elastic scattering of 10.1 GeV/ c K − mesons on protons, based on a sample of 16 261 kinematically-fitted bubble-chamber events. The differential cross section is given over the | t |- range of 0.06 to 2.5 GeV 2 and is fitted with the expressions a e bt , A e Bt + Ct 2 and ( P e Qt + Re St ) over various intervals of t . The results are compared with those of other experiments at nearby energies. Upper limits of | α | < 0.28 and σ B < 0.4 μ b (both at a 90% confidence level) are given for the ratio of real to imaginary part of the forward-scattering amplitude and the backward-elastic-scattering cross section, respectively.
No description provided.
ERROR INCLUDES STATISTICAL ERROR AND ERROR IN TOTAL CROSS SECTION USED FOR NORMALIZATION. EXTRAPOLATION OF D(SIG)/DT TO T=0 PROVIDES ABOUT 0.5 PCT UNCERTAINTY.
NO BACKWARD EVENTS OBSERVED. LARGEST ANGLE EVENT SEEN WAS AT 64 DEG (-T = 2.33 GEV**2).
We present improved measurements of the differential production rates of stable charged particles in hadronic Z0 decays, and of charged pions, kaons and protons identified over a wide momentum range using the SLD Cherenkov Ring Imaging Detector. In addition to flavor-inclusive Z0 decays, measurements are made for Z0 decays into light (u, d, s), c and b primary flavors, selected using the upgraded Vertex Detector. Large differences between the flavors are observed that are qualitatively consistent with expectations based upon previously measured production and decay properties of heavy hadrons. These results are used to test the predictions of QCD in the Modified Leading Logarithm Approximation, with the ansatz of Local Parton-Hadron Duality, and the predictions of three models of the hadronization process. The light-flavor results provide improved tests of these predictions, as they do not include the contribution of heavy-hadron production and decay; the heavy-flavor results provide complementary model tests. In addition we have compared hadron and antihadron production in light quark (as opposed to antiquark) jets. Differences are observed at high momentum for all three charged hadron species, providing direct probes of leading particle effects, and stringent constraints on models.
Production rates of all stable charged particles. The statistical and systematic errors are shown separately for the momentum distribution. They are combined in quadrature for the other two distributions. The first DSYS error is due tothe uncertainty in the track finding efficiency and the second DSYS error is th e rest of the systematic error.
The charged pion fraction and differential production rate per hadronic Z0 decay.
The charged kaon fraction and differential production rate per hadronic Z0 decay.
The polarization parameter has been measured for K − p elastic scattering at nine incident beam momenta between 0.955 and 1.272 GeV/ c covering the c.m. angular range −0.9 < cos θ ∗ < + 0.9 . Experimental results and coefficients of Legendre polynomial fits to the data are presented and compared with other measurements and a partial-wave analysis.
No description provided.
LEGENDRE POLYNOMIAL COEFFICIENTS FOR POLARIZATION DERIVED USING INTERPOLATED DIFFERENTIAL CROSS SECTION DATA OF B. CONFORTO ET AL., NP B105, 189 (1976).
The DELPHI experiment at LEP uses Ring Imaging Cherenkov detectors for particle identification. The good understanding of the RICH detectors allows the identification of charged pions, kaons and proto
Mean particle multiplicities for Z0-->Q-QBAR events. The second systematic (DSYS) error is due to the extrapolation of the differential distributions to the full kinematic range.
Mean particle multiplicities for Z0-->B-BBAR events. The second systematic (DSYS) error is due to the extrapolation of the differential distributions to the full kinematic range.
Mean particle multiplicities for Z0-->(U-UBAR,D-DBAR,S-SBAR) events. The second systematic (DSYS) error is due to the extrapolation of the differential distributions to the full kinematic range.
Forum