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We revisit general arguments for the absence of exact continuous globalsymmetries in string compactifications and extend them to D-brane models. Weelucidate the various ways approximate continuous global symmetries arise inthe 4-dimensional effective action. In addition to two familiar methods -axionic Peccei-Quinn symmetries and remnant global abelian symmetries fromGreen-Schwarz gauge symmetry breaking - we identify new ways to generateapproximate continuous global symmetries. Two methods stand out, both of whichoccur for local brane constructions within the LARGE volume scenario of modulistabilisation. The first is the generic existence of continuous non-abelianglobal symmetries associated with local Calabi-Yau isometries. These symmetriesare exact in the non-compact limit and are spontaneously broken by the LARGEvolume, with breaking effects having phenomenologically interesting sizes \sim0.01 for plausible choices for underlying parameters. Such approximate flavoursymmetries are phenomenologically attractive and may allow the fermion masshierarchies to be connected to the electroweak hierarchy via the large volume.The second is the possible existence of new hyper-weak gauge interactions underwhich Standard Model matter is charged, with \alpha_{HW} \sim 10^{-9}. Suchgroups arise from branes wrapping bulk cycles and intersecting the local(resolved) singularity on which the Standard Model is supported. We discussexperimental bounds for these new gauge bosons and their interactions with theStandard Model particles.

Continuous Global Symmetries and Hyperweak Interactions in String Compactifications