A new measurement of the rare decay eta -> pi^0 gamma gamma with the Crystal Ball/TAPS detectors at the Mainz Microtron

The A2 at MAMI collaboration Nefkens, B.M.K. ; Prakhov, S. ; Aguar-Bartolome, P. ; et al.
Phys.Rev.C 90 (2014) 025206, 2014.
Inspire Record 1297221 DOI 10.17182/hepdata.64169

A new measurement of the rare, doubly radiative decay eta->pi^0 gamma gamma was conducted with the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. New data on the dependence of the partial decay width, Gamma(eta->pi^0 gamma gamma), on the two-photon invariant mass squared, m^2(gamma gamma), as well as a new, more precise value for the decay width, Gamma(eta->pi^0 gamma gamma) = (0.33+/-0.03_tot) eV, are based on analysis of 1.2 x 10^3 eta->pi^0 gamma gamma decays from a total of 6 x 10^7 eta mesons produced in the gamma p -> eta p reaction. The present results for dGamma(eta->pi^0 gamma gamma)/dm^2(gamma gamma) are in good agreement with previous measurements and recent theoretical calculations for this dependence.

1 data table

D(WIDTH(ETA --> PI0 GAMMA GAMMA))/DM**2(GAMMA GAMMA) obtained from the data of 2007 and 2009 and their average. The error on the average is the total error.


INCLUSIVE AND SEMIINCLUSIVE PRODUCTION OF POSITIVE PIONS AND PROTONS IN ANTI-P P INTERACTIONS AT 22.4-GEV/C

The ALMA ATA-DUBNA-HELSINKI-MOSCOW-PRAGUE-TBILISI collaboration Boos, E.G. ; Ermilova, D.I. ; Samoilov, V.V. ; et al.
Nucl.Phys.B 174 (1980) 45-67, 1980.
Inspire Record 159212 DOI 10.17182/hepdata.7929

New results on the inclusive and semi-inclusive production of π + mesons and protons in the whole phase space are given for about 2.2 · 10 4 inelastic p p interactions at 22.4 GeV/ c . A method of statistical separation for spectra of particles of the same charge which are produced in CP -symmetrical reactions is discussed in detail. Experimental data are compared with quark-parton model predictions.

3 data tables

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NON-ANNIHILATION EVENTS ONLY.

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MEASUREMENT OF THE AVERAGE ENERGY OF CHARGED PARTICLES IN C.M.S FOR THE ANTI-P P INTERACTIONS AT 22.4-GEV/C.

The ALMA ATA-DUBNA-MOSCOW-PRAGUE-TBILISI-HELSINKI collaboration Boos, E.G. ; Ermilova, D.I. ; Samoilov, V.V. ; et al.
Yad.Fiz. 31 (1980) 947-955, 1980.
Inspire Record 157619 DOI 10.17182/hepdata.18035

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7 data tables

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Inclusive rho0 Production in anti-p p Interactions at 22.4-GeV/c

The Alma Ata-Dubna-Helsinki-Kosice-Moscow-Prague collaboration Ermilova, D.I. ; Filippova, V.V. ; Samoilov, V.V. ; et al.
Nucl.Phys.B 137 (1978) 29, 1978.
Inspire Record 122943 DOI 10.17182/hepdata.35097

Inclusive ϱ 0 production has been investigated in p p reactions at 22.4 GeV/ c . The total cross section for ϱ 0 production is 8.1 ± 2.0 mb. The average ϱ 0 's per event is 0.17 ± 0.03. The average transverse momentum, as obtained by extrapolation of a fitted simple exponential to the p T 2 distribution, is 0.52 ± 0.12 GeV/ c . The Feynman x and c.m. rapidity distributions show ϱ 0 to be “centrally” produced.

2 data tables

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Single Particle Inclusive Spectra of Charged Particles in anti-p p Interactions at 22.4-GeV/c

The Alma Ata-Dubna-Helsinki-Kosice-Moscow-Prague collaboration Boos, E.G. ; Samoilov, V.V. ; Takibaev, Zh.S. ; et al.
Nucl.Phys.B 121 (1977) 381-392, 1977.
Inspire Record 109633 DOI 10.17182/hepdata.35465

The inclusive spectra for p p collisions at 22.4 GeV/ c are investigated. We show that the transverse momentum distributions resemble those in high-energy pp interactions and discuss the influence of annihilation processes on the p T 2 distributions. The invariant inclusive cross section for pions in the central region is found to be 28 ± 1 mb. A charge asymmetry is indicated by the y ∗ spectrum in the central region, the asymmetry parameter having the value 0.15 ± 0.01. Finally, we estimate the upper limit of the diffraction dissociation of the beam particle to be 3.68 −0.15 +0.45 mb.

10 data tables

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Study of the Reaction $\bar{p} p \to p X$ at 22.4-{GeV}/$c$

The Alma Ata-Dubna-Helsinki-Kosice-Moscow-Prague-Tbilisi collaboration Batyunya, B.V. ; Boguslavsky, I.V. ; Dashian, N.B. ; et al.
Sov.J.Nucl.Phys. 33 (1981) 64-66, 1981.
Inspire Record 154173 DOI 10.17182/hepdata.69635

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49 data tables

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INVARIANT CROSS-SECTIONS FOR THE INCLUSIVE REACTIONS anti-p p ---> pi+ X AND anti-p p ---> p X AT 22.4-GeV/c

The Alma Ata-Dubna-Helsinki-Moscow-Prague collaboration Boos, E.G. ; Ermilova, D.I. ; Samoilov, V.V. ; et al.
Nuovo Cim.A 47 (1978) 377, 1978.
Inspire Record 130221 DOI 10.17182/hepdata.37561

Invariant inclusive cross-sections for π+-mesons and protons from\(\bar pp\) reactions at 22.4 GeV/c are presented. The average multiplicity for the production of π+-mesons is 1.92±0.02 and for protons 0.41±0.02. Annihilation spectra have been approximated by using the difference between\(\bar pp\) and pp data. The resulting distributions have similar gross features as the total\(\bar pp\) data.

1 data table

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INCLUSIVE K0(S) LAMBDA AND anti-LAMBDA PRODUCTION IN anti-p p INTERACTIONS AT 22.4-GeV/c

The Alma Ata-Dubna-Helsinki-Moscow-Prague-Tbilisi collaboration Batyunya, B.V. ; Boguslavsky, I.V. ; Gramenitsky, I.M. ; et al.
Z.Phys.C 25 (1984) 213, 1984.
Inspire Record 194651 DOI 10.17182/hepdata.2004

InclusiveKs0, Λ and\(\bar \Lambda\)-production has been investigated in\(\bar p\)p-interactions at 22.4 GeV/c. Total and topological cross sections and multiplicity characteristics of neutral strange particles have been determined. DifferentialKs0 and Λ-cross sections and also characteristics of annihilation processes with neutral kaon production have been studied. It is shown that the difference of the shapes of the invariantx-distributions forK-mesons in the fragmentation region for annihilation and non-annihilation processes can be described in the framework of the “dual” valon model, but not by considering the current (undressed) quark recombination mechanisms only. The polarization of Λ and\(\bar \Lambda\)-hyperons has been measured.

4 data tables

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CROSS-SECTION OF TWO PRONG EXCLUSIVE REACTIONS IN anti-p p INTERACTIONS AT 22.4-GeV/c

The Alma Ata-Dubna-Moscow-Prague-Helsinki collaboration Batyunya, B.V. ; Boguslavsky, I.V. ; Bruncko, D. ; et al.
Czech.J.Phys.B 38 (1988) 257-266, 1988.
Inspire Record 239395 DOI 10.17182/hepdata.38967

The results of the cross-section determination of some two-prong final states with one neutral particle (1 C-fits) in ¯pp-interactions at 22.4 GeV/c are presented. These results have been obtained from pictures of the HBC “Ludmila”.

1 data table

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Charged Multiplicity Distributions in Anti-n $p$ Interactions at 6-{GeV}/c

The Alma Ata-Dubna-Moscow-Prague-Serpukhov-Sofiya-Tbilisi-Helsinki collaboration Batyunya, B.V. ; Boguslavsky, I.V. ; Gramenitsky, I.M. ; et al.
JINR-E1-80-164, 1980.
Inspire Record 153456 DOI 10.17182/hepdata.39557

None

2 data tables

Axis error includes +- 0.0/0.0 contribution (?////).

Axis error includes +- 0.0/0.0 contribution (?////).