Constructing de Sitter space and Dark Matter with Dynamical Tension Strings

TL;DR

The work develops a dynamical-tension string theory within the modified measures framework, where each string carries its own tension via a worldsheet measure $\Phi(\varphi)$ and an auxiliary gauge sector. By coupling to a bulk scalar field and introducing worldsheet currents, the tension becomes $T_i = e\phi + T_i$ per string, and conformal invariance on multiple strings imposes relations among tensions and the tension field $\phi$. In particular, a two-tension setup yields braneworld configurations in which a de Sitter space is induced on the brane, evading swampland constraints, with flat and conformally transformed seed geometries connected by the conformal factor $\Omega^2$. Furthermore, standard string interactions between strings of different tensions decouple, motivating a dark-string DM scenario where dark strings (with distinct tensions) share the same compactification and spacetime, potentially yielding dark copies of the Standard Model with different parameters. Altogether, the paper presents a mechanism for de Sitter realizations in a dynamical-tension string theory and a novel DM paradigm based on tension diversity among strings.

Abstract

The string tensions can be dynamical in the modified measure formalism and appear as an additional dynamical degrees of freedom . These tensions may not be universal, instead, each string generates its own tension. We then consider a new bulk field that can couple to the strings, the tension scalar which changes locally the tension along the world sheet. In the case with two string tensions there is a braneworld solution which gives rise to an induced de Sitter space in the brane, avoiding swampland constraints of the standard string theory. Strings with different tension to ours can appear also as Dark Matter and since they share the same space and compactifications as visible matter, they should lead to Dark copies of the standard model,