Narrow Angle Pairs of Particles from Nuclear Interactions

Lord, J. J.; Fainberg, J.; Haskin, D. M.; Schein, Marcel

doi:10.1103/physrev.87.538

Cited by 13 publications

(3 citation statements)

References 9 publications

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“…The conclusion of this work was that "the most probable value of τ (π 0 ) is ≈ 5 × 10 −15 s" (Anand, 1953). Perkins has pointed out that this value should be corrected downward due to the reduction in ionizing power when the e + e − pair are very close together (Perkins, 1955) and this is the direction needed to bring this result into better agreement with the upper limits of 2 × 10 −15 s and 1 × 10 −15 s found in cosmic ray emulsion experiments (Lord et al, 1950) as well as in low energy experiments on pion charge exchange at the Chicago cyclotron (Lord et al, 1952). It should also be noted that the long lifetime claimed by Anand (Anand, 1953) depends strongly on the π 0 momentum distribution in the cosmic rays, a quantity that is not well determined in the emulsion experiments.…”

Section: Early Experimental Historymentioning

confidence: 83%

Neutral pion lifetime measurements and the QCD chiral anomaly

Bernstein

Holstein

2013

Rev. Mod. Phys.

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A fundamental property of QCD is the presence of the chiral anomaly, which is the dominant component of the π 0 → γγ decay rate. Based on this anomaly and its small ( 4.5%) chiral correction, a prediction of the π 0 lifetime can be used as a test of QCD at confinement scale energies. The interesting experimental and theoretical histories of the π 0 meson are reviewed, from discovery to the present era.Experimental results are in agreement with the theoretical prediction, within the current ( 3%) experimental error; however, they are not yet sufficiently precise to test the chiral corrected result, which is a firm QCD prediction and is known to 1% uncertainty. At this level there exist experimental inconsistencies, which require attention. Possible future work to improve the present precision is suggested.

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Section: Early Experimental Historymentioning

confidence: 83%

Neutral pion lifetime measurements and the QCD chiral anomaly

Bernstein

Holstein

2013

Rev. Mod. Phys.

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“…11 Steinberger 12 has very recently found that two percent of TT° decays result directly in an electron pair and a single gamma, in competition with the two-gamma process.…”

Section: Resultsmentioning

confidence: 99%

The Scattering and Absorption ofπ+Mesons by Aluminum

Tracy¹

1953

Phys. Rev.

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The interaction of TT + mesons with aluminum has been studied in a magnet cloud chamber containing five f-inch aluminum plates. Meson energies ranged from 25 to 100 Mev. 20 stops, 34 scatters >30°, and 57 stars were observed. A 1-prong star and a 70-Mev electron-positron pair in coincidence was interpreted as an inelastic charge-exchange scatter. All stops are reasonably accounted for by scatters and stars hidden by the geometry. The cross sections rise steeply with energy. The scattering (elastic plus inelastic) is very roughly isotropic except for a dip in the 60° to 90° interval Corrected absolute cross sections for the 25-45-, 45-70-, and 70-100-Mev intervals, respectively, are o-(scat), 70±23, 312=fc74, and 216±82 mb; o-(star), 176±34, 299db62, and 332±100 mb; and

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“…First observations of a few events came in emulsions [22,23,24] and then via counter techniques where a γ and an electron were detected in coincidence [25]. Following that, two cloud chamber experiments yielded around 30 events each [21,26].…”

Section: Previous Measurements Of B(πmentioning

confidence: 99%

A Measurement of the Branching Ratio of the π<sup>0</sup> Dalitz Decay using K(L) → 3 π<sup>0</sup> Decays from KTeV

Abouzaid

2007

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We present a measurement of B(π 0 → e + e − γ)/B(π 0 → γγ) using data taken in 1999 by the E832 KTeV experiment at Fermilab. The π 0 s were produced by K L decays in flight that are fully reconstructed. We find 63, 693 K L → 3π 0 → γγ γγ e + e − γ decays in KTeV data (an increase of a factor of ∼ 20 in event statistics over previous experiments), and normalize to K L → 3π 0 → 6γ, to extractwhere the first error is statistical and the second is systematic. Using the Mikaelian and Smith prediction for the e + e − mass spectrum as implemented in the KTeV Monte Carlo to correct to the full e + e − mass range yieldsThis result is consistent with previous measurements and with theoretical predictions, and the uncertainty is a factor of three smaller than any previous measurement.iii Other faculty members here also deserve thanks. I am grateful to Henry Frisch for giving me the opportunity to work with him during my first year in Chicago.Mark Oreglia invited me to become involved in several outreach programs with a local public school which I enjoyed immensely. Thanks also to Stuart Gazes; even after I was finished with my classes, I knew he cared about how I was doing.

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Narrow Angle Pairs of Particles from Nuclear Interactions

Cited by 13 publications

References 9 publications

Neutral pion lifetime measurements and the QCD chiral anomaly

Neutral pion lifetime measurements and the QCD chiral anomaly

The Scattering and Absorption ofπ+Mesons by Aluminum

A Measurement of the Branching Ratio of the π<sup>0</sup> Dalitz Decay using K(L) → 3 π<sup>0</sup> Decays from KTeV

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