Darmstadt 2016 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 64: Hadron Structure and Spectroscopy XI

HK 64.2: Talk

Friday, March 18, 2016, 14:30–14:45, S1/01 A5

Isoscalar Single Pion Production in the Energy Region of Roper and d^*(2380) Resonances^*. — •Tatiana Skorodko¹, Mikhail Bashkanov², and Heinz Clement¹ for the WASA-at-COSY collaboration — ¹Physikalisches Institut, Uni Tübingen — ²School of Physics and Astronomy, University of Edinburgh, UK

The single pion production in NN collisions may be decomposed into its isoscalar and isovector parts, which give important information about the pion production mechanism – in particular on the role of isoscalar and isovector resonance excitations in the course of the reaction process.

Wheareas the isovector pion production being sensitive to baryonic Δ excitations is reasonably well known from threshold up to several GeV, the isoscalar pion production has been determined experimentally only for beam energies below 1 GeV. The reason is that the isoscalar strength needs pn collisons for its experimental extraction.

In order to obtain information about the isoscalar strength above 1 GeV WASA data for the reactions pp → ppπ⁰ and pn → ppπ⁻ at T_p = 1.2 GeV are being analyzed. Since these reactions have been taken in the quasifree mode by use of a deuterium target, the beam energy region of 1.0 - 1.3 GeV is covered, which is just the region of the Roper N(1440) baryon resonance and of the d^*(2380) dibaryon resonance. We observe a pronounced signal from the Roper resonance, in particular in the ppπ⁻ channel. A possible, though unlikely contribution from d^*(2380) is being searched for.

^*supported by DFG (CL 214/3-1) and STFC (ST/L00478X/1)