Berlin 2005 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 16: Elektromagnetische und Hadronische Proben
HK 16.4: Vortrag
Montag, 7. März 2005, 14:45–15:00, TU MA001
η and η′ photoproduction off the deuteron and off the proton — •Igal Jaeglé — Universität Basel, CH-4056 Basel, Klingelbergst. 82
The photoproduction of η and η′ mesons off the deuteron and off the
proton has been measured up to 2.8GeV at the tagged photon beam of the Bonn ELSA accelerator with a combined setup
of the Crystal Barrel and TAPS detectors, which formed a 4π electromagnetic calorimeter.
For the deuteron, the mesons were detected in coincidence with the (participant) recoil nucleons.
Models predict a strong rise of the ratio at higher energies due to the contribution from other
resonances such as D15(1675). An alternative explanation is the possible photoexcitation of the non-strange
pentaquark state, which is associated with the second member of an antidecuplet
of exotic baryons. Angular distributions and photon beam asymetries will be
analysed in view of these effects.
Furthermore the invariant mass region around 2 GeV where many resonances are
predicted is still not very well explored. The finding and
investigation of selective channels which couple only to a very small number
of resonances is very desirable. In that sense, the photoproduction of
η′ mesons off the proton is a promising tool, since at threshold
only a few partial waves contribute. So far, the current data status is very poor and insensitive.
The measurement of η′ production off the deuteron is
the first attempt to study this reaction on the neutron. It aims furthermore at
an investigation of the threshold behaviour (η′ nucleon - interaction)
on the deuteron.
We will discuss preliminary results.