10-12 April 2019
Denver, CO
US/Mountain timezone
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Contribution contributed talk

Denver, CO - Director's Row H

Photoproduction of the d*(2380) Dibaryon


  • Dr. Stephen KAY

Primary authors



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