Closed Bosonic String Field Theory at Quintic Order II: Marginal Deformations and Effective Potential

Understand

We verify that the dilaton together with one exactly marginal field, form a moduli space of marginal deformations of closed bosonic string field theory to polynomial order five.

• We use the results of this successful check in order to find the best functional form of a fit of quintic amplitudes.
• We then use this fit in order to accurately compute the tachyon and dilaton effective potential in the limit of infinite level.
• We observe that to order four, the effective potential gives unexpectedly accurate results for the vacuum.