Multihadron production by electron-positron colliding beams has been investigated for total centre-of-mass energies ranging from 1.2 to 2.4 GeV. The total cross-section, σtot ≡ σ(e+e−→π+π−+ + anything), is of the order of σμμ ≡ σ(e+e−→μ+μ−), with a threshold near 1 GeV. Partial cross-sections for the various channels are also derived. The cross-section of the specific channel e+e−→π+π−π+π− exhibits an energy dependence which is suggestive of a heavier vector meson, ρ' (mρ,≈ 1.6 GeV,Гρ, ≈ 350 Mev), having the same quantum numbers as the ρ-meson. An upper limit is given for the coupling constantfρ′ (fρ′/4π<18, wherefρ′=mρ′2e/gγρ′). Final states withG+ parity are found to be much more abundant than those withG− parity. The average multiplicity (charged plus neutral final-state pions) is found to be betweet 4 and 5 over all the energy range explored.
No description provided.
VALUES OF R CALCULATED FROM TOTAL CROSS SECTION.
No description provided.
None
THIS HADRON PAIR CROSS SECTION PROVIDES ONLY AN UPPER LIMIT TO THE PION FORM FACTOR ABOVE 1.5 GEV SINCE KAON PRODUCTION IS NOT DISTINGUISHED.
We have determined the pion charge exchange cross section on hydrogen for π ° mesons emitted at 180° by measuring neutron time-of-flight. Using known values of the p-wave phase shifts we have deduced the contribution of the s-wave. We obtain a value for the quantity a 1 − a 3 (in h = c = m =1 units where m is the pion mass) =0.270±0.014 in agreement within the errors with recent theoretical calculations. We also find a value of 114±55 μb / sr for the cross section in the center of mass system for radiative pion capture at 22.6 MeV (gamma ray emitted at 180°).
No description provided.
We present experimental results on the K + n → K + n differential cross sections measured in deuterium at 13 momenta between 0.64 and 1.51 GeV/ c .
REACTION HAS A SPECTATOR PROTON. WHILE SOME DEUTERIUM CORRECTIONS HAVE BEEN APPLIED, THESE DATA ARE NOT DIVIDED BY THE DEUTERIUM FORM FACTOR APPEARING IN THE IMPULSE APPROXIMATION.
The target asymmetry T = ( σ ↑ − σ ↓)/( σ ↑ + σ ↓) for the reaction γ p → π + n has been measured at the Bonn 2.5 GeV electron synchrotron for a pion c.m. angle of 40° and γ energies between 0.5 and 2.2 GeV. Butanol was used as the target material. About 35% of the protons could be polarized using the dynamic-polarization method in a continuous-flow cryostat operating at 1°K and 25 kG. The π + mesons were detected in a magnetic-spectrometer system. Considerable structure in the asymmetry was observed.
Axis error includes +- 11/11 contribution.
The observation of 70 000 K 0 p π + events produced with K + incident momenta of 1.21, 1.29, 1.38 and 1.69 GeV/ c allows a detailed description of the production and decay of the Δ(1236) and K ∗ (892) resonances which dominate the K 0 p π + final state. No striking variations with energy are observed. The associated production of Δ and K ∗ near threshold shows striking similarities with the same production at higher energy.
INCLUDING 1 PCT SYSTEMATIC ERROR ON CORRECTIONS.
FIT 'A', ALLOWING FOR DELTA-K* INTERFERENCE (TWO OTHER FITS GIVEN IN PAPER).
S-CHANNEL HELICITY FRAME.
The average multiplicities 〈 n c 〉 and 〈n〉, of charged-plus-neutral pions produced in e + e − collisions, have been determined for total center-of-mass energies ranging from 1.2 to 2.4 GeV. No appreciable multiplicity variation is observed over this energy range, where the mean values 〈; n c 〉 = 3.3 +0.3 −0.2 and 〈 n 〉 = 4.4 +0.4 −0.2 are found.
No description provided.
VALUES OF R CALCULATED FROM TOTAL CROSS SECTION.
The differential cross section has been measured for the reaction γ +p→p+ π o at the Bonn 2.5 GeV electron synchrotron in the energy range from 0.4 to 2.2 GeV for a c.m. angle of 150 degrees. The protons were detected in a magnetic spectrometer system. The excitation curve shows a distinct resonance structure. The total corrections to the counting rate are about 3%. The contribution of the process γ +p→p+2 π was separated. The uncertainty of this separation leads to an error of about 4% in the cross section.
No description provided.
No description provided.
From the energy dependence of the p¯p and p¯n inelastic cross sections we deduce an upper limit to the resonant contribution in p¯p backward scattering for c.m. energies between 1915 and 1950 MeV. This limit is smaller than the expected contribution from diffraction scattering. The energy dependence of the 180° p¯p elastic cross section in this energy range cannot therefore be directly related to the formation of s-channel resonances.
CROSS SECTION ONLY FOR ANNIHILATION EVENTS WITH EMISSION OF SPECTATOR PROTON TOO SLOW TO GIVE A VISIBLE TRACK (LESS THAN ABOUT 80 MEV/C) - ABOUT 60 PCT OF TOTAL ANNILILATION. NUMERICAL VALUES TAKEN FROM TABLE 2 OF R. BIZZARRI ET AL., NC 22A, 225 (1974).
Data at nine π+ momenta are presented in the following three-body final states: Σ+K+π0, Σ+K0π+, Σ0K+π+, ΛK+π+, pK+K¯0. The data consist of cross sections, Dalitz plots, and angular distributions for the quasi-two-body final state Y*+(1385)K+. In the channel Y*+(1385)K+ the production and Y* decay distributions are compared with the predictions of Stodolsky and Sakurai.
No description provided.
EVENTS ABOVE BACKGROUND - NO FIT.
DATA VALUES TAKEN FROM PDG2 CHEW 73B COMPILATION WHICH READ THEM FROM THE GRAPH AND CONVERTED TO MUB. BACKGROUND NOT SUBTRACTED.
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