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Tsirkov, D.; Azaryan, T.; Baru, V.; Chiladze, D.; Dymov, S.; Dzyuba, A.; Gebel, R.; Goslawski, P.; Hanhart, C.; Hartmann, Michael; Kacharava, A.; Khoukaz, A.; Komarov, V.I.; Kulessa, P.; Куликов, А. И.; Kurbatov, V.; Lensky, Vadim; Lorentz, B.; Macharashvili, G.; Mchedslishvili, D.; Mielke, M.; Mikirtytchiants, S.; Merzliakov, S.; Nioradze, M.; Ohm, H.; Papenbrock, M.; Rathmann, F.; Serdyuk, V.; Shmakova, V.; Ströher, H.; Uzikov, Yu. N.; Valdau, Yu.; Wilkin, C.

doi:10.1016/j.physletb.2012.05.004

Cited by 14 publications

(16 citation statements)

References 21 publications

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“…Our earlier experiments [25,26], and the one reported here, were carried out in the vicinity of 353 MeV and, at such a low beam energy, one may expect that very few pion partial waves will contribute. Keeping terms up to pion d waves, there are three possible transitions from the I = 1 initial state, viz.…”

Section: Partial Wave Decompositionmentioning

confidence: 61%

“…As parts of this program, we have already reported on measurements at T p = 353 MeV of the cross sections dσ/dΩ and proton analyzing powers A p y in the pp → {pp} s π 0 reaction [25] and the quasi-free pn → {pp} s π − reaction, where a polarized proton beam was incident on a deuterium target [26]. We here complement this information through measurements in inverse kinematics, with a polarized deuteron beam colliding with a polarized hydrogen target.…”

Section: Introductionmentioning

confidence: 99%

“…III. A particular concern here compared to our previous work at ANKE [25,26] is the use of the polarized gas target cell that was required in order to achieve a viable luminosity. Naturally, high and well determined beam and target polarizations are critical in any measurement of a spin correlation but, because the differential cross section had already been measured [26], an absolute normalisation was of much lesser importance.…”

Section: Introductionmentioning

confidence: 99%

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Measurement of spin observables in the quasifreenp→{pp}sπ−reaction at 353 MeV

Dymov¹,

Shmakova²,

Azaryan³

et al. 2013

Phys. Rev. C

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The transverse spin correlations Ax,x and Ay,y have been measured in the d p → pspec{pp}sπ − reaction at COSY-ANKE at 353 MeV per nucleon. Here {pp}s denotes a proton-proton pair with low excitation energy, which is dominantly in the 1 S0 state. By measuring three protons in the final state it was possible to extract events where there was a spectator proton pspec so that the reaction could be interpreted in terms of quasi-free n p → {pp}sπ − . The proton analyzing power in this reaction was also deduced from this data set by averaging over the polarization of the deuteron beam. The values of A p y were shown to be consistent with a refined analysis of our earlier results obtained with a polarized proton incident on a deuterium target. Taking these data in combination with our previous measurements of the differential cross sections and analyzing powers in the pp → {pp}s π 0 reaction, a more robust partial wave decomposition was achieved. Three different acceptable solutions were found and the only way of resolving this ambiguity without further theoretical input would be through a measurement of the mixed spin-correlation parameter Ax,z.

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Section: Partial Wave Decompositionmentioning

confidence: 61%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Measurement of spin observables in the quasifreenp→{pp}sπ−reaction at 353 MeV

Dymov¹,

Shmakova²,

Azaryan³

et al. 2013

Phys. Rev. C

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“…The beam polarisation and luminosity were determined by detecting simultaneously the pp → dπ + and pp → pp processes, for which the cross sections and analysing powers are known with high precision at this energy. [6]. Open (red) circles are CELSIUS data obtained at 360 MeV [7].…”

Section: The Pp → { Pp} S π 0 Processmentioning

confidence: 99%

“…Keeping terms up to pion d waves, the pp → {pp} s π 0 data at 353 MeV [6] p-wave terms because of the very strong coupling between the incident 3 S 1 and 3 D 1 waves. Although there is a significant overall relative uncertainty between the π − and π 0 production data, associated with luminosity and other systematic effects, the combined system is actually over determined [8].…”

Section: Partial Wave Analysismentioning

confidence: 99%

Near-threshold pion production in diproton reactions with polarised beams and target at ANKE-COSY

Dymov

2012

EPJ Web of Conferences

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Abstract. An extensive experimental study of near-threshold pion production in diproton reactions is underway at the ANKE-COSY spectrometer (Jülich). The programme is aimed at isolating the four-nucleon-pion contact interaction term appearing in the χPT expansions of these processes. This will establish links between pion production and other low energy phenomena within the χPT approach. The first step in the programme was to measure the differential cross-section and the proton analysing power in the pp → {pp} s π 0 and pn → {pp} s π − reactions over the full angular range. Here {pp} s denotes a diproton, i.e.,a two-proton system in a 1 S 0 state. These data allow a partial wave analysis to be carried out provided that simplifying assumptions are made when applying the Watson theorem. To make the analysis more robust, and independent of the uncertainties in the relative normalization, the spin-correlation coefficients A x,x and A y,y in the n p → {pp} s π − reaction were measured in a follow-up experiment. The first results of the data analysis are presented and future developments of the programme are outlined. The physics case for near-threshold single pion productionThe ANKE [1] experimental programme on the near-threshold pion production aims to measure the cross sections and spin observables in the pp → {pp} s π 0 and np → {pp} s π − reactions [2,3]. The symbol {pp} s here denotes a diproton, that is, an unbound proton pair with a very low excitation energy, E pp < 3 MeV. The selection of a low excitation energy ensures the dominance of the 1 S 0 state of the diproton, which simplifies significantly the theoretical analysis. A full data set of all observables at low beam energies would allow us to determine the partial wave amplitudes which, in turn, would provide a non-trivial test of chiral perturbation theory [4] and also lead to the determination of the value of the parameter d, which represents the important contact term that affects the pion p-wave amplitudes.The short range physics in chiral effective field theories, which provide a model-independent understanding of Nature, is encoded in the so-called low energy constants (LEC). These LECs, once determined from one process, can be applied to predict many others. For example, the LECs c1-c4 extracted from πN analysis on the basis of chiral perturbation theory are now widely used to parameterise the short range physics in the NN-interaction, few-nucleon systems, single (and multi-) pion production in NN collisions etc. Analogously, by studying the p-wave pion production amplitudes we get access to the 4Nπ contact operator, the strength of which is controlled by the low energy constant d. This LEC enters also in electroweak processes, such as pp → de + ν and triton β decay, in few-body operators (e.g. in pd → pd), pion photoproduction γd → nnπ + and its inverse πd → γNN. It therefore plays a very important role in connecting different low-energy reactions.On the practical side, the pp → {pp} s π 0 and np → {pp} s π − reactions have the big advantage f...

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