Lectures on Superstring Phenomenology

Abstract

The phenomenological aspects of string theory are briefly reviewed. Emphasis is given to the status of 4D string model building, effective Lagrangians, model independent results, supersymmetry breaking and duality symmetries.

Figures (3)

• Figure 1: A 2D torus $T^2$ defined by the identification of points on ${\rm I R}^2$ by elements of the lattice defined by ${\bf e_1}$ and ${\bf e_2}$. We display examples of a closed string on ${\rm I R}^2$ which is also closed on $T^2$ ($n=0$), also a string closed on $T^2$ but not on ${\rm I R}^2$, winding around the torus once($n=1$) and twice ($n=2$).
• Figure 2: Starting from the two-torus $T^2$, we generate the orbifold $O^2\equiv T^2/{\bf Z}^2$, 'the ravioli', by the identification $\vec{x}\leftrightarrow -\vec{x}$. $O^2$ is singular at the four 'fixed points' shown. Besides the momentum and winding states of the torus, the orbifold spectrum also has 'twisted' states, corresponding to strings closed in $O^2$ but not on $T^2$. The twisted states are attached to fixed points, we display one example.
• Figure 3: The $T$-duality invariant potential from gaugino condensation. Notice that the potential blows-up at large compactification radius and the minimum is at small radius ($R^2\sim 1.2$ in string units) as desired.