Strings with a different tension as dark matter

Abstract The string and brane tensions do not have to be put in by hand, they can be dynamically generated, as in the case when we formulate string and brane theories in the modified measure formalism. Here we take the measure as a metric independent lagrange multiplier that forces some lagrangian density to be zero. Then string tension appears, but as an integration constant. It can be seen however that these string tensions are not universal, but rather each string and each brane generates its own tension. To make the string tension fully dynamical, a bulk field (the tension field) is introduced. As we have seen in previous publications, world sheet conformal invariance in the case of two different species of strings with different tension can produce braneworlds, Swampland constraints may be avoided. Here we introduce braneworld scenarios without singularities of the string tensions, although they still can grow to very large values, this is done by demanding a certain periodicity in one light like coordinate. Now we add another crucial observation; Dark matter to us may consist of matter made out of strings with different tensions because of decoupling of standard string interactions for strings with different tensions, although interactions mediated by the tension field can exist between strings of different tensions.