Building the Standard Model on a D3-brane

Abstract

We motivate and apply a bottom-up approach to string phenomenology, which aims to construct the Standard Model as a decoupled world-volume theory on a D3-brane. As a concrete proposal for such a construction, we consider a single probe D3-brane on a partial resolution of a del Pezzo 8 singularity. The resulting world-volume theory reproduces the field content and interactions of the MSSM, however with a somewhat extended Higgs sector. An attractive feature of our approach is that the gauge and Yukawa couplings are dual to non-dynamical closed string modes, and are therefore tunable parameters.

Figures (9)

• Figure 1: Our bottom-up approach to string phenomenology assumes that the Standard Model is localized on a D3-brane at the apex of a highly warped throat. The D3-brane theory is accurately described via a decoupling limit, in which the Planck scale is sent off to infinity, leaving behind a non-compact Calabi-Yau singularity.
• Figure 2: The MQSSM is the minimal quiver extension of the Standard Model, as obtained via the rules (a)-(e).
• Figure 3: The 2-cycles $\alpha_i$ are identified with nodes on the $E_8$ Dynkin diagram.
• Figure 4: D7, D5 and D3-branes wrapped 4-, 2- and 0-cycles of the internal manifold.
• Figure 5: Quiver diagram of the D3-brane gauge theory on a del Pezzo 8 singularity, corresponding to the exceptional collection of fractional branes given in eqn (\ref{['coll2']}). This is the same quiver diagram as that of the D3-brane theory near a ${\bf C}^3/\Delta_{27}$ orbifold singularity. The connection between the two theories is explained below.