arXiv subjects
Publications and source records attributed to Pascal Anastasopoulos.
This proceeding is based on arXiv:0905.3044. We analyze the problem of the hierarchy of masses and mixings in orientifold realizations of the Standard Model. We present a bottom-up brane configuration that can generate such hierarchies.
We analyze the problem of the hierarchy of masses and mixings in orientifold realizations of the Standard Model. We find bottom-up brane configurations that can generate such hierarchies.
We use the combined action of Z_2-chiral reflections (T-dualities) and shifts to build N=1,2 supersymmetric four-dimensional string compactifications with few moduli. In particular, we consider Z_2^4 asymmetric orbifolds of Type IIB on the maximal torus of SO(12) that mimic N=2 Calabi-Yau compactifications with small "effective" Hodge numbers starting from (h_{11}, h_{21})=(1,1). We analyze possible unoriented projections, providing Type I examples with or without open strings. N=1 oriented asymmetric shift-orbifolds of Type IIB with few chiral multiplets are also presented.
We study an extension of the MSSM by an anomalous abelian vector multiplet and a Stückelberg multiplet. The anomalies are cancelled by the Green-Schwarz mechanism and the addition of Chern-Simons terms. The advantage of this choice over the standard one is that it allows for arbitrary values of the quantum numbers of the extra U(1). As a first step towards the study of hadron annihilations producing four leptons in the final state (a clean signal which might be studied at LHC) we then compute the decays $Z'\to Z_0 \g$ and $Z'\to Z_0 Z_0$. We find that the largest values of the decay rate is $\sim 10^{-4}$ GeV, while the expected number of events per year at LHC is at most of the order of 10.
This proceeding is based on hep-th/0605225 and it shows that the most general anomaly related effective action contains Stuckelberg, axionic and Chern-Simons-like couplings. Such couplings are generically non-trivial in orientifold string vacua. A similar analysis in quantum field theories provides similar couplings. These Chern-Simons couplings generate new signals which might be visible at LHC.
We derive general formulae for tree level gauge couplings and their one-loop thresholds in Type I models based on genuinely interacting internal N=2 SCFT's, such as Gepner models. We illustrate our procedure in the simple yet non-trivial instance of the Quintic. We briefly address the phenomenologically more relevant issue of determining the Weinberg angle in this class of models. Finally we initiate the study of the correspondence between `magnetized' or `coisotropic' D-branes in Gepner models and twisted representations of the underlying N=2 SCA.