Abstract
The helicity-dependent cross sections for the photoproduction of π0η pairs have been measured for the first time. The experiment was performed at the tagged photon facility of the Mainz MAMI accelerator with the combined Crystal Ball – TAPS calorimeter. The experiment used a polarized deuterated butanol target and a circularly polarized photon beam. This arrangement allowed the σ1/2 (photon and target spin antiparallel) and σ3/2 (parallel spins) components to be measured for quasi-free production of π0η pairs off protons and neutrons. The main finding is that the two helicity components contribute identically, within uncertainties, for both participant protons and neutrons. The absolute couplings for protons and neutrons are also identical. This means that nucleon resonances contributing to this reaction in the investigated energy range have almost equal electromagnetic helicity couplings, A1/2 n,p and A3/2 n,p. Identical couplings for protons and neutrons are typical for Δ resonances and identical A1/2 and A3/2 components are only possible for J≥3/2 states, which constrains possible contributions of nucleon resonances.
| Original language | English |
|---|---|
| Pages (from-to) | 305-312 |
| Number of pages | 8 |
| Journal | Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics |
| Volume | 786 |
| DOIs | |
| Publication status | Published - 10 Nov 2018 |
Fingerprint
ASJC Scopus subject areas
- Nuclear and High Energy Physics
Cite this
First measurement of helicity-dependent cross sections in π0η photoproduction from quasi-free nucleons. / (A2 Collaboration at MAMI).
In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol. 786, 10.11.2018, p. 305-312.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - First measurement of helicity-dependent cross sections in π0η photoproduction from quasi-free nucleons
AU - (A2 Collaboration at MAMI)
AU - Käser, A.
AU - Dieterle, M.
AU - Witthauer, L.
AU - Abt, S.
AU - Achenbach, P.
AU - Adlarson, P.
AU - Afzal, F.
AU - Ahmed, Z.
AU - Ahrens, J.
AU - Annand, J. R.M.
AU - Arends, H. J.
AU - Bashkanov, M.
AU - Beck, R.
AU - Biroth, M.
AU - Borisov, N. S.
AU - Braghieri, A.
AU - Briscoe, W. J.
AU - Cividini, F.
AU - Collicott, C.
AU - Costanza, S.
AU - Denig, A.
AU - Downie, E. J.
AU - Drexler, P.
AU - Fix, A.
AU - Garni, S.
AU - Glazier, D. I.
AU - Gorodnov, I.
AU - Gradl, W.
AU - Günther, M.
AU - Gurevich, G. M.
AU - Heijkenskjöld, L.
AU - Hornidge, D.
AU - Huber, G. M.
AU - Kashevarov, V. L.
AU - Kay, S.
AU - Keshelashvili, I.
AU - Kondratiev, R.
AU - Korolija, M.
AU - Krusche, B.
AU - Lazarev, A. B.
AU - Lisin, V.
AU - Livingston, K.
AU - Lutterer, S.
AU - MacGregor, I. J.D.
AU - Manley, D. M.
AU - Martel, P. P.
AU - Metag, V.
AU - Meyer, W.
AU - Miskimen, R.
AU - Mornacchi, E.
PY - 2018/11/10
Y1 - 2018/11/10
N2 - The helicity-dependent cross sections for the photoproduction of π0η pairs have been measured for the first time. The experiment was performed at the tagged photon facility of the Mainz MAMI accelerator with the combined Crystal Ball – TAPS calorimeter. The experiment used a polarized deuterated butanol target and a circularly polarized photon beam. This arrangement allowed the σ1/2 (photon and target spin antiparallel) and σ3/2 (parallel spins) components to be measured for quasi-free production of π0η pairs off protons and neutrons. The main finding is that the two helicity components contribute identically, within uncertainties, for both participant protons and neutrons. The absolute couplings for protons and neutrons are also identical. This means that nucleon resonances contributing to this reaction in the investigated energy range have almost equal electromagnetic helicity couplings, A1/2 n,p and A3/2 n,p. Identical couplings for protons and neutrons are typical for Δ resonances and identical A1/2 and A3/2 components are only possible for J≥3/2 states, which constrains possible contributions of nucleon resonances.
AB - The helicity-dependent cross sections for the photoproduction of π0η pairs have been measured for the first time. The experiment was performed at the tagged photon facility of the Mainz MAMI accelerator with the combined Crystal Ball – TAPS calorimeter. The experiment used a polarized deuterated butanol target and a circularly polarized photon beam. This arrangement allowed the σ1/2 (photon and target spin antiparallel) and σ3/2 (parallel spins) components to be measured for quasi-free production of π0η pairs off protons and neutrons. The main finding is that the two helicity components contribute identically, within uncertainties, for both participant protons and neutrons. The absolute couplings for protons and neutrons are also identical. This means that nucleon resonances contributing to this reaction in the investigated energy range have almost equal electromagnetic helicity couplings, A1/2 n,p and A3/2 n,p. Identical couplings for protons and neutrons are typical for Δ resonances and identical A1/2 and A3/2 components are only possible for J≥3/2 states, which constrains possible contributions of nucleon resonances.
UR - http://www.scopus.com/inward/record.url?scp=85054879201&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85054879201&partnerID=8YFLogxK
U2 - 10.1016/j.physletb.2018.10.006
DO - 10.1016/j.physletb.2018.10.006
M3 - Article
VL - 786
SP - 305
EP - 312
JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
SN - 0370-2693
ER -