Lecture 30 Jan

Focus for today: the light front gauge:

1. light-front (LF) coordinates X^+, X^- ;
2. noncovariant physical gauges, such as LF gauge, for handling string worldsheet reparametrization invariance;
3. consequences for string equations of motion, boundary conditions, conserved momenta, and constraints;
4. open string mode expansion, and the special case of X^- in LF gauge;
5. Virasoro modes;
6. the classical string mass formula.

The relevant chapter of Zwiebach (Z) is chapter (ch.)9.