Speaker
Dr
Stephen Kay
(University of Regina)
Description
The field of multiquark states (beyond the known meson qq and baryon qqq states) has had renewed interest
in recent years with findings of potential four, five and six quark states. Recent experiments by the WASA-
at-COSY and HADES collaborations have observed a dibaryon (6q) resonant state, the d*(2380). Numerous
measurements of this state across a range of different hadronic production channels indicate properties of M
= 2380 MeV, Γ = 70 MeV and I(J p ) = 0(3 + ). So far no photoproduction channels have been examined.
A new measurement by the A2 collaboration at MAMI aims to observe the d*(2380) from a photoproduction
reaction for the first time. A new large acceptance recoil polarimeter measures the final state spin polarisation
of nucleons from the D(~γ ,~n p) deuteron photodisintegration reaction. A range of polarisation observables are
measurable with this configuration. Establishing that the d*(2380) has an electromagnetic coupling opens
up opportunities to constrain its size and internal structure. First results from the analysis of the data will
be presented, including the recently published results for Σ in the energy range 420-620 MeV. Preliminary
results for the recoil polarisation observable, C x 0 , across the energy range relevant to the d*(2380) will also
be presented.
This research was supported: The UK Science and Technologies Funding Council (STFC), Studentship
1526286, Grants ST/L00478X/1 and ST/L005824/1 and the Natural Sciences and Engineering Research
Council of Canada (NSERC), FRN: SAPIN-2016-00031
Primary author
Dr
Stephen Kay
(University of Regina)
Co-author
Dr
Mikhail Bashkanov
(University of York)
