Abstract Superstring/M-theory is the theory of quantum gravity that can provide UV-completion to viable inflation models. We modify Starobinsky model by adding Bel-Robinson tensor T μνλρ squared term proposed as leading correction inspired superstring theory. The ( R + 1/6 m 2 - β /8 6 ) under consideration has two parameters: inflaton mass and string-inspired positive parameter . derive equati...

Synopsis: (i) how superstring theories are unified by M-theory; (ii) how superstring and supermembrane properties follow from the D=10 and D=11 supersymmetry algebras; (iii) how D=10 and D=11 supergravity theories determine the strong coupling limit of superstring theories; (iv) how properties of type II p-branes follow from those of M-branes. Over the decade from 1984-94 superstring theory cam...

It has been conjectured that at the stationary point of the tachyon potential for the non-BPS D-brane or brane-anti-D-brane pair of superstring theories, the negative energy density cancels the brane tension. We study this conjecture using a cubic superstring field theory with insertion of a double-step inverse picture changing operator. We compute the tachyon potential on levels 1 and 4, obtai...

We discuss various superstring effective actions and, in particular, their common sector which leads to the so-called pre-big-bang cosmology (cosmology in a weak coupling limit of heterotic superstring). Then, we review the main ideas of the Hořava-Witten theory which is a strong coupling limit of heterotic superstring theory. Using the conformal relationship between these two theories we prese...

We investigate heterotic string-type model-building for the recently-proposed fractional superstring theories. We concentrate on the cases with critical spacetime dimensions four and six, and find that a correspondence can be drawn between the new fractional superstring models and a special subset of the traditional heterotic string models. This allows us to generate the partition functions of ...

We discuss properties of D-brane configurations in the matrix model of type IIB superstring recently proposed by Ishibashi, Kawai, Kitazawa and Tsuchiya. We calculate central charges in supersymmetry algebra at infinite N and associate them with oneand five-branes present in IIB superstring theory. We consider classical solutions associated with threeand five-branes and calculate their interact...

These five lectures give an elementary introduction to perturbative superstring theory, superstring phenomenology, and the fermionic construction of perturbative string models. These lectures assume no prior knowledge of string theory.