We have updated our measurement of the cross section for e^+e^- -> psi(3770) -> hadrons, our publication "Measurement of sigma(e^+e^- -> psi(3770) -> hadrons) at E_{c.m.} = 3773 MeV", arXiv:hep-ex/0512038, Phys.Rev.Lett.96, 092002 (2006). Simultaneous with this arXiv update, we have published an erratum in Phys.Rev.Lett.104, 159901 (2010). There, and in this update, we have corrected a mistake in the computation of the error on the difference of the cross sections for e^+e^- -> psi(3770) -> hadrons and e^+e^- -> psi(3770) -> DDbar. We have also used a more recent CLEO measurement of cross section for e^+e^- -> psi(3770) -> DDbar. From this, we obtain an upper limit on the branching fraction for psi(3770) -> non-DDbar of 9% at 90% confidence level.
Measured cross section for the process E+ E- --> PSI(3770) --> hadrons.
We report values of $R = \sigma(e^+e^-\to {hadrons})/\sigma(e^+e^-\to\mu^+\mu^-)$ for 85 center-of-mass energies between 2 and 5 GeV measured with the upgraded Beijing Spectrometer at the Beijing Electron-Positron Collider.
Measured values of R.
Using the upgraded Beijing Spectrometer (BESII), we have measured the total cross section for $e^+e^-$ annihilation into hadronic final states at center-of-mass energies of 2.6, 3.2, 3.4, 3.55, 4.6 and 5.0 GeV. Values of $R$, $\sigma(e^+e^-\to {hadrons})/\sigma(e^+e^-\to\mu^+\mu^-)$, are determined.
Data are corrected for acceptance and radiative effects.
None
R measurement.
D* 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.
We report experimental results on the cross section for the reaction e + e − → hadrons as a function of the total c.m. energy in the range W = 1.42–3.09 GeV. The results, combined with those already existing below the charm threshold, clearly indicate a structure for R ( W ) = α ( e + e − → hadrons)/ α ( e + e − → μ + μ − ) in that energy region.
THE ENERGY RANGES OF THE NEW DATA AND THE PREVIOUS (REVISED) DATA OVERLAP BETWEEN 1.9 AND 2.0 GEV. RADIATIVE CORRECTIONS HAVE BEEN APPLIED TO ALL DATA. THIS CROSS SECTION EXCLUDES TWO-BODY FINAL STATES.
AVERAGE CHARGED AND NEUTRAL MULTIPLICITY. QUOTED ERRORS ARE STATISTICAL ONLY.
First results from the magnetic detector PLUTO at the new e + e − storage ring PETRA are shown. The ratio R of the cross section for hadron production to that for μ-pair production has been measured to be R = 5.0 ± 0.5 at 13 GeV and 4.3 ±0.5 at 17 GeV. Both values have an additional systematic error of 20%. The events show a typical 2-jet structure. The mean transverse momentum approaches a constant value with increasing energy implying a shrinkage of the jet opening angle.
TAU HEAVY LEPTON PAIR CONTRIBUTIONS HAVE BEEN SUBTRACTED. R AT 13 AND 17 GEV, TOGETHER WITH SOME SELECTED LOWER ENERGY MEASUREMENTS FROM PLUTO AT DORIS.
Data from earlier preprint DESY-79-06. NUMERICAL VALUES MEASURED OFF GRAPH IN PREPRINT.
The total cross section for e + e − annihilation into hadronic final states between 3.6 and 5.2 GeV was measured by the nonmagnetic inner detector of DASP, which has similar trigger and detection efficiencies for photons and charged particles. The measured difference in R = σ had / σμμ between 3.6 GeV and 5.2 GeV is ΔR = 2.1 ± 0.3. We observe three peaks at cm energies of 4.04, 4.16 and 4.417 GeV, the parameters of which, when interpreted as resonances, are given.
EXCLUDING CONTRIBUTION OF TAU HEAVY LEPTON.
INCLUDING CONTRIBUTION OF TAU HEAVY LEPTON.
Using the solenoidal magnetic detector PLUTO, we have measured the total cross section for e + e − annihilation into hadrons. Results are presented for center of mass energies between 3.6 and 4.8 GeV, and in the regions of the J ψ (3.1) and ψ(3.7) resonances. We also present results for the 2 prong cross section in the energy range 3.6 to 4.8 GeV.
No description provided.
NUMBERS MEASURED OFF PUBLISHED FIGURE. RADIATIVE CORRECTIONS HAVE BEEN APPLIED.
We observe a resonancelike structure in the total cross section for hadron production by e+e− colliding beams at a mass of 4414 ± 7 MeV having a total width Γ=33±10 MeV. From the area under this resonance, we deduce the partial width to electron pairs to be Γee=440±140 eV. Further structure of comparable width is present near 4.1 GeV.
No description provided.