Contact Terms, Symmetries and D-Instantons
نویسنده
چکیده
The scattering of NS ⊗ NS antisymmetric tensor states in the presence of D-instantons in type IIB superstring theory is studied. It is shown that in order to preserve gauge invari-ance, spacetime supersymmetry and picture changing symmetry the inclusion of boundary contact terms for closed string antisymmetric tensor vertex operators is necessary.
منابع مشابه
Note on discrete gauge anomalies.
We consider the probem of gauging discrete symmetries. All valid constraints on such symmetries can be understood in the low energy theory in terms of instantons. We note that string perturbation theory often exhibits global discrete symmetries, which are broken non-perturbatively.
متن کاملSUSY breaking mediation by D-brane instantons
It is well known that D-brane instantons can generate contributions to the effective superpotential of gauge theories living on D-branes which are perturbatively forbidden by global U(1) symmetries. We extend this idea to theories with supersymmetry breaking, studying the effect of D-brane instantons stretched between the SUSY-breaking and visible sectors. Analogously to what happens in the SUS...
متن کاملInstanton Induced Open String Superpotentials and Branes at Singularities
We study different aspects of the non-perturbative superpotentials induced by Euclidean E3-branes on systems of D3/D7-branes located at Abelian orbifold singularities. We discuss in detail how the induced couplings are consistent with the U(1) symmetries carried by theD3/D7 branes. We construct different compact and non-compact examples, and show phenomenologically relevant couplings like μ-ter...
متن کاملStringy Instantons and Yukawa Couplings in MSSM-like Orientifold Models
Type IIA orientifold constructions with intersecting D6-branes and their IIB duals in terms of magnetized D9/D7-branes constitute one of the most promising avenues for the construction of semirealistic MSSMlike compactifications. One generic problem with these constructions is, that there are many Yukawa couplings, which vanish due to additional U(1) symmetries in the theory. In this paper we c...
متن کاملSmall Instantons and Weak Scale String Theory
We consider heterotic string compactifications to four dimensions when instantons shrink to zero size. If the standard model gauge group originates from the new gauge symmetry associated with the small instantons singularity, then the weakly or strongly coupled heterotic string scales can be taken to be arbitrarily low. The SO(32) and E8×E8 gauge groups can then be very weakly coupled even at t...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 1997