Year: 2004
Type: article
Abstract: The nonperturbative behavior of strings in type IIA pp wave backgrounds with a compact lightlike direction is investigated using matrix string theory. At small string coupling, ${g}_{s}\ensuremath{\ll}1,$ the behavior is determined by the combination ${\mathrm{Mg}}_{s}$ where M is a dimensionless parameter proportional to the strength of the Ramond-Ramond background. For ${\mathrm{Mg}}_{s}\ensuremath{\ll}1,$ the matrix string theory is conventional; only the degrees of freedom in the Cartan subalgebra contribute, and the theory reduces to copies of the perturbative string. For ${\mathrm{Mg}}_{s}\ensuremath{\gg}1,$ the theory admits degenerate vacua representing fundamental strings blown up into fuzzy spheres with nonzero light-cone momenta. We determine the spectrum of small fluctuations around these vacua. Around such a vacuum all ${N}^{2}$ degrees of freedom are excited with comparable energies. The spectrum of masses has a spacing that is independent of the radius of the fuzzy sphere, in agreement with the expected behavior of continuum giant gravitons. For ``reducible'' vacua we find that the momenta of fluctuations are generically irrational multiples of the inverse radius of the compact direction, showing that these blown up strings never close.
Institution: University of Kentucky
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W1993817934