Coherent<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msup><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msup></mml:math>photoproduction on lightest nuclei

Egorov, M. V.; Fix, A.

doi:10.1016/j.nuclphysa.2014.10.002

Cited by 21 publications

(31 citation statements)

References 23 publications

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“…where contributions from the coherent γd → π 0 π 0 d reaction are negligible, which was estimated in [57] well below the 100 nb level and preliminary analyses of the present data support this result. As shown in Fig.…”

Section: Systematic Uncertaintiessupporting

confidence: 86%

Photoproduction of $ \pi^{0}$ -pairs off protons and off neutrons

Dieterle¹,

Oberle²,

Ahrens³

et al. 2015

Eur. Phys. J. A

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Abstract. Total cross sections, angular distributions, and invariant-mass distributions have been measured for the photoproduction of π 0 π 0 pairs off free protons and off nucleons bound in the deuteron. The experiments were performed at the MAMI accelerator facility in Mainz using the Glasgow photon tagging spectrometer and the Crystal Ball/TAPS detector. The accelerator delivered electron beams of 1508 and 1557 MeV, which produced bremsstrahlung in thin radiator foils. The tagged photon beam covered energies up to 1400 MeV. The data from the free proton target are in good agreement with previous measurements and were only used to test the analysis procedures. The results for differential cross sections (angular distributions and invariant-mass distributions) for free and quasi-free protons are almost identical in shape, but differ in absolute magnitude up to 15%. Thus, moderate final-state interaction effects are present. The data for quasi-free neutrons are similar to the proton data in the second resonance region (final-state invariant masses up to ≈ 1550 MeV), where both reactions are dominated by the N (1520)3/2 − → Δ(1232)3/2 + π decay. At higher energies, angular and invariant-mass distributions are different. A simple analysis of the shapes of the invariant-mass distributions in the third resonance region is consistent with strong contributions of an N → Nσ decay for the proton, while the reaction is dominated by a sequential decay via a Δπ intermediate state for the neutron. The data are compared to predictions from the Two-Pion-MAID model and the Bonn-Gatchina coupled-channel analysis.

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Section: Systematic Uncertaintiessupporting

confidence: 86%

Photoproduction of $ \pi^{0}$ -pairs off protons and off neutrons

Dieterle¹,

Oberle²,

Ahrens³

et al. 2015

Eur. Phys. J. A

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“…The calculation reproduces the data surprisingly well. A calculation performed by Egorov and Fix based [32] on the QFC mechanism also gives a similar excitation function as shown in Fig. 1 (dotted line).…”

supporting

confidence: 63%

Non-strange dibaryons studied in the γd → π0π0d reaction

et al. 2019

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Coherent double neutral-pion photoproduction on the deuteron, γd→π 0 π 0 d, has been experimentally studied at incident photon energies ranging from 0.75 to 1.15 GeV. The total cross section as a function of the γd center-of-mass energy shows resonance-like behavior, which peaks at approximately 2.47 and 2.63 GeV. The measured angular distribution of deuteron emission is rather flat, which cannot be reproduced by the kinematics of quasifree π 0 π 0 production with deuteron coalescence. In π 0 d invariant-mass distributions, a clear peak is observed at 2.14±0.01 GeV/c 2 with a width of 0.09±0.01 GeV/c 2 . The spin-parity of this state is restricted to 1 + , 2 + or 3 − from the angular distributions of the two π 0 s. The present work shows strong evidence for the existence of an isovector dibaryon resonance with a mass of 2.14 GeV/c 2 . The 2 + assignment is consistent with the theoretically predicted D 12 state, and also with the energy dependence of the πd partial-wave amplitude 3 P 2 for the π ± d→π ± d and π + d→pp reactions.

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“…In this respect the reaction γd → dπ 0 π 0 appears to be attractive, since there the conventional processes are expected to be particularly small [408,409]. In the energy region of d * (2380) the conventional cross section is predicted to be below 20 nb.…”

Section: Electromagnetic Excitation Of D * (2380)mentioning

confidence: 99%