E 8 Flavour Multiplets

We analyze gauge symmetry enhancements SO(16) → E8 on eight D7-branes and SO(14) × U(1) → E8 on seven D7-branes from open strings. String configurations which we present in this paper are closely related to the ones given by Gaberdiel and Zwiebach. Our construction is based on SO(8)×SO(8) decomposition and its relation to the D8-brane case via T-duality is clearer. Then we study supersymmetric Yang-Mills theory on D3-brane near the D7-branes. This theory has flavour symmetry group which is equal to the gauge group on D7-branes. We suggest that when this symmetry is enhanced, two dyons make bound states which, together with elementary quarks, constitute an E8 multiplet. [email protected] Supported in part by Grant-in-Aid for Scientific Research from Ministry of Education, Science and Culture (#5416).