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We present the results of an experiment to search for associated charm production near threshold in 13-GeV/c π−p interactions. A large aperture PWC spectrometer was sensitive to the decay fragments of the forward-produced D*−’s expected from the two-body reactions π−+p→D*−+Λc+,Σc +,. . . . The missing baryon mass was determined from the vector momenta of the incident pion and the candidate D*−. No evidence for these reactions was found, which resulted in a 7-nb upper limit (95% confidence level) for each of the cross sections σ(π−p→D*−Λc+) and σ(π−p→D*−Σc+).
Axis error includes +- 0.0/0.0 contribution (?////NOT GIVENDECAY-BR(BRN=D*(2010)- --> AD0 PI-,BR=64 IN PCT)//DECAY-BR(BRN=AD0 --> K+ PI-, BR=3 IN PCT)).
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The Mark II detector at SPEAR has been used to study D-meson production in e+e− annihilation at center-of-mass energies between 3.8 and 6.7 GeV. The neutral and charged D mesons are identified from their K∓π± and K∓π±π± decay modes. Measurements of RD and of the inclusive differential cross section s dσdz are presented. The quasi-two-body cross sections σDD¯, σD*D¯, and σD*D¯* are derived from an overall fit to the D recoil spectra. No evidence was found for the associated production of charmed mesons and charmed baryons.
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THE DIFFERENTIAL SCALING CROSS SECTION FOR NEUTRAL AND CHARGED D'S. DEFINITION OF Z IS 2*E(P=3)/SQRT(S).
A search for production of D*−'s using the decay chain D0π−, D0→K+π−, was carried out at the Brookhaven National Laboratory multiparticle spectrometer with a 16-GeV/c π− beam and a hydrogen target. At 95% confidence level the upper limits for the product of peripheral production cross section by branching ratio are 2.4 nb for inclusive D*− production and 1.3 nb for the exclusive channel π−p→D*−Λc.
UPPER LIMIT TO CROSS SECTIONS.
We have measured the inclusive cross section for η production in e+e− interactions near charm threshold using the Crystal Ball detector. No pronounced structure in the energy dependence is observed. By comparing cross sections above and below charm threshold we obtain the limits (90% confidence limit): R(e+e−→FF¯X)RB(F→ηx)<0.15−0.32 (for Ec.m. from 4.0 to 4.5 GeV), RB(D→ηx)<0.13. Our results are inconsistent with a previous report of a large energy dependence of the η cross section ascribed to the crossing of the FF* and F*F* production thresholds.
Axis error includes +- 0.0/0.0 contribution (?////DECAY PI0 --> 2GAMMA//RES-DEF(RES=ETA,BACK=CORRECTED,DEF=340 < M( 2GAMMA ) < 800 MEV)//DECAY-BR(BRN=ETA --> 2GAMMA,BR=38 PCT)).
THE 4.028 GEV DATA ARE NOT INCLUDED IN THE 4.005-4.082 GEV BIN. Axis error includes +- 0.0/0.0 contribution (?////DECAY PI0 --> 2GAMMA//RES-DEF(RES=ETA,BACK=CORRECTED,DEF=340 < M( 2GAMMA ) < 800 MEV)//DECAY-BR(BRN=ETA --> 2GAMMA,BR=38 PCT)).
AT FIXED ENERGIES.
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CHARGED AND NEUTRAL D MESON INCLUSIVE CROSS SECTIONS.
RATIO R FOR D PRODUCTION - THE FACTOR OF TWO ACCOUNTS FOR THE FACT THAT CHARMED PARTICLES ARE PRODUCED IN PAIRS.
FIT TO D AND D* PRODUCTION IN THRESHOLD REGION. RESULTS FOR ANISOTROPIC FIT (ASSUMING ISOTROPIC D* DECAY IS ALMOST IDENTICAL).
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We present a measurement of the cross section for hadron production by e+e− annihilation in the vicinity of the previously observed resonance near 3.77 GeV. The data are used to determine the parameters of the ψ(3770) resonance. The values found are: mass, 3764±5 MeV/c2, total width, 23.5±5 MeV, and partial width to electron pairs, 276±50 eV.
THESE RESULTS ARE ALSO IN THE THESIS OF R. H. SCHINDLER, SLAC-219 (1979), THE RECORD OF WHICH CONTAINS THE TABULATED CROSS SECTIONS.
BREIT-WIGNER RESONANCE PLUS BACKGROUND FIT TO RADIATIVELY CORRECTED DATA YIELDS RESONANCE MASS OF 3764 +- 5 MEV, TOTAL WIDTH OF 23.5 +- 5 MEV AND PARTIAL WIDTH TO ELECTRON PAIRS OF 276 +- 50 EV.
PEAK CROSS SECTION FOR D MESON PAIR PRODUCTION AT PSI(3770) RESONANCE. J/PSI, PSI(3684) AND CONTINUUM BACKGROUND (R=2.5) SUBTRACTED.
We present measurements of the cross section for inclusive D and K meson production in e + e − annihilation in the center of mass energy range 3.6 to 5.8 GeV. D production accounts for most of the increase in the total cross section for hadron production in e + e − annihilation at energies above 4 GeV.
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