SLIDE 5 Perturbation series & nonperturbative effect (bosonic string)
๐ = 0 noncritical string (2D pure gravity) ๐ฃ = ๐๐ข
2๐บ:
(๐ขโ5
4 โผ ๐๐ก: C.C. or string coupling)
perturbative soln.: ๐ฃ = โโฅ0 ๐ฃโ ๐ข
1 2โ5 2โ = โโฅ0 ๐ฃโ ๐๐ก
โ2+2โโ ๐ฃโ โผ ๐ทโ2โ 2โ !:
๏ฎ characteristic of string (vol. of moduli sp. of Riemann surface) cf. particle: ๐! ๏ฎ nonperturbative ambiguity:
Borel transf.: ๐ฃ โ
๐ฃ ๐ก = โโฅ0
๐ฃโ 2โ ! ๐๐ก โ2+2โ๐ก2โ~ 1 1โ
๐ก ๐ท /๐๐ก 2
inverse: ๐ฃ =
โ
๐ฃ ๐ก ๐โ๐ก๐๐ก โผ
โ 1 1โ
๐ก ๐ท /๐๐ก 2 ๐โ๐ก๐๐ก
โ ambiguity โผ ๐
โ ๐ท
๐๐ก, where ๐ท: instanton action in MM = tension of D-brane
5
๐ก
๐ท/๐๐ก
Brezin-Kazakov '90 Gross-Migdal โ90 Douglas-Shenker '90
๐ฃ2 +
1 6 ๐๐ข 2๐ฃ = ๐ข
large order behavior