TY - JOUR

T1 - Ramond-Ramond fields, fractional branes and orbifold differential K-theory

AU - Szabo, Richard J.

AU - Valentino, Alessandro

PY - 2010/1

Y1 - 2010/1

N2 - We study D-branes and Ramond-Ramond fields on global orbifolds of Type II string theory with vanishing H-flux using methods of equivariant K-theory and K-homology. We illustrate how Bredon equivariant cohomology naturally realizes stringy orbifold cohomology. We emphasize its role as the correct cohomological tool which captures known features of the low-energy effective field theory, and which provides new consistency conditions for fractional D-branes and Ramond-Ramond fields on orbifolds. We use an equivariant Chern character from equivariant K-theory to Bredon cohomology to define new Ramond-Ramond couplings of D-branes which generalize previous examples. We propose a definition for groups of differential characters associated to equivariant K-theory. We derive a Dirac quantization rule for Ramond-Ramond fluxes, and study flat Ramond-Ramond potentials on orbifolds. © Springer-Verlag 2009.

AB - We study D-branes and Ramond-Ramond fields on global orbifolds of Type II string theory with vanishing H-flux using methods of equivariant K-theory and K-homology. We illustrate how Bredon equivariant cohomology naturally realizes stringy orbifold cohomology. We emphasize its role as the correct cohomological tool which captures known features of the low-energy effective field theory, and which provides new consistency conditions for fractional D-branes and Ramond-Ramond fields on orbifolds. We use an equivariant Chern character from equivariant K-theory to Bredon cohomology to define new Ramond-Ramond couplings of D-branes which generalize previous examples. We propose a definition for groups of differential characters associated to equivariant K-theory. We derive a Dirac quantization rule for Ramond-Ramond fluxes, and study flat Ramond-Ramond potentials on orbifolds. © Springer-Verlag 2009.

UR - http://www.scopus.com/inward/record.url?scp=76349109459&partnerID=8YFLogxK

U2 - 10.1007/s00220-009-0975-1

DO - 10.1007/s00220-009-0975-1

M3 - Article

SN - 0010-3616

VL - 294

SP - 647

EP - 702

JO - Communications in Mathematical Physics

JF - Communications in Mathematical Physics

IS - 3

ER -