Using data collected with the ARGUS detector, we have performed a decay angular analysis of the enhancement, previously known as the D ∗ (2420), seen in the final state D ∗ (2010) + π − . We thereby exhibit that the observed broad structure is actually due to two relatively narrow resonances, one of which is identified as the D ∗ (2459) 0 , while the massof the other is measured to be (2414±2±5) MeV/ c 2 . The results of the analysis are in good agreement with the interpretation of the two states as L =1 D mesons of spin-parities 2 + and 1 + respectively.
The cross sections times branching ratio.
It is assumed that decays D PION and D* PION saturate the total widths.
Using the ARGUS detector at the DORIS II e + e - storage ring at DESY, we have observed a new charmed meson of mass (2469±4±6) MeV/ c 2 , decaying to D 0 π + . This state is a strong candidate for the charged isospin partner of the D ∗ (2459) 0 . The isospin mass splitting is measured to be (14±5±8) MeV / c 2 .
The cross section times branching ratio.
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.
Results of fitting the differential distributions in x F and p T 2 of D mesons produced in 400 GeV/ c p-p interactions to the form d 2 σ d x F d p T 2 ∝(1−x F ) n exp [−(p T 2 /〈p T 2 〉)] are discussed. The D + distribution is found to be relatively hard [ n =3.1±0.8〈 P t 2 〉=1.32±0.27 (GeV/ c ) 2 ] and the D̄ 0 distribution relatively soft [ n =8.1±1.9,〈 p T 2 〉=0.62±0.14 (GeV/ c ) 2 ] compared to the average for all D's [ n =4.9±0.5,〈 p T 2 〉=0.99±0.10 (GeV/ c ) 2 ]. It is suggested that these distributions could reflect contribution of leading di-quarks in pp collisions. Comparison is made with evidence for leading quarks in charm production in 360 GeV/ cπ − p interactions.
The invariant (C=INV) and non-invariant (C=NON-INV) distributions are fitted to (1-XL)**POWER. Pt distribution is fitted to EXP(-PT**2/SLOPE).
The p¯4He annihilation cross section averaged over the interval 40–50 MeV/ c has been measured using a streamer chamber in a magnetic field. The measured value is 1342±250 mb. It agrees with a behaviour like 1/ p of the annihilation cross section. Our result has been obtained at the lowest momentum achieved till now in measurements of antiproton annihilation in flight.
No description provided.
We have observed six unambiguous decays of the charmed strange baryon Ξ c + (or charge conjugate Ξ c − ) in the 230 GeV/c negative pions or kaons on a copper target at the CERN SPS using silicon microstrip detectors and charge-coupled devices for vertex reconstruction. Three of them have been reconstructed through the decay chain Ξ c + → Ξ − π + π + , Ξ − → Λ 0 π − , Λ 0 → pπ − and the other three through the decay chain Ξ c + → Σ + K − π + → pπ 0 . We present our measurements of the mass, lifetime and production cross-section of the Ξ c + , as well as of the branching ration for the two decay modes.
The cross sections times branching ratio, linear A-dependence is assumed.
We have measured the rate of D ∗± meson production inside the jets produced in p p collisions at √ s = 630 GeV. For jets in the transverse energy range 15< E T <60 GeV we find a production rate of 0.10±0.04±0.03 D ∗± per jet, which is in good agreement with perturbative QCD calculations. In addition, we find that the D ∗± fragmentation distribution is strongly peaked towards low z consistent with gluon splitting as the dominant production mechanism.
No description provided.
None
No description provided.
A measurement of Δσ L (np), the difference between neutron-proton total cross sections in pure longitudinal spin states, is described. Data were taken for five energies between 500 and 800 MeV, with statistical errors of ≈ 1.5 mb and an estimated normalization error of 6%. The data, combined with other results, show some evidence for an elastic I =0 spin-singlet resonance with mass ∼ 2213 MeV and width ∼ 74 MeV, or a coupled-triplet resonance with similar mass and width.
SIG(C=PARALLEL)-SIG(C=ANTIPARALLEL) means the difference in the total crosssection with initial parallel and antiparallel longitudinal spin states. The I0 means I=0, these values were found using interpolated Delta(sigma(pp)) data.
From 2540 Z 0 → τ + τ − events, we determine the inclusive decay branching fractions of the τ -lepton into one and three charged particles to be 0.856 ± 0.006 (stat.) ± 0.003 (syst.) and 0.144 ± 0.006 (stat.) ± 0.003 (syst.), respectively. The leptonic branching fractions are measured to be 0.175 ± 0.008 (stat.) ± 0.005 (syst.) for τ → μν μ ντ and 0.177 ± 0.007 (stat.) ± 0.006 (syst.) for τ → eν e ν τ . We determined the τ lifetime both from three-prong decays using the decay length and from one-prong decays using the impact parameter. The results from the two independent methods agree and yield a combined value of [0.309 ± 0.023 (stat.) ± 0.030 (syst.)] × 10 −12 s.
ALPHAS extracted from the ratio of the branching fractions.
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