ar X iv : h ep - t h / 04 05 15 1 v 1 1 7 M ay 2 00 4 IFT - UAM / CSIC - 04 - 24 Strings on Eight - Orbifolds

ar X iv : h ep - t h / 04 05 15 1 v 2 1 J un 2 00 4 IFT - UAM / CSIC - 04 - 24 Strings on Eight - Orbifolds

We present several examples of T/P orbifolds with P ⊂ SU4. We compute their Hodge numbers and consider turning on discrete torsion. We then study supersymmetric compactifications of type II, heterotic, and type I strings on these orbifolds. Heterotic compactifications to D=2 have a B-field tadpole with coefficient given by that of the anomaly polynomial. In the SO32 heterotic with standard embe...

ar X iv : h ep - p h / 04 05 09 5 v 1 1 1 M ay 2 00 4 Flavour Symmetries and Kähler Operators

Any supersymmetric mechanism to solve the flavour puzzle would generate mixing both in the superpotential Yukawa couplings and in the Kähler potential. In this paper we study, in a model independent way, the impact of the nontrivial structure of the Kähler potential on the physical mixing matrix, after kinetic terms are canonically normalized. We undertake this analysis both for the quark secto...

ar X iv : h ep - p h / 04 05 11 9 v 1 1 3 M ay 2 00 4 The Lorentz and CPT violating effects on the charged

ar X iv : h ep - p h / 04 05 03 9 v 1 5 M ay 2 00 4 η , η ′ → π + π − γ with coupled channels

ar X iv : h ep - t h / 05 03 04 3 v 3 1 8 Ju l 2 00 5 TAUP -

We study closed N = 2 strings on orbifolds of the form T /Z2 and C /Z2. We compute the torus partition function and prove its modular invariance. We analyze the BRST cohomology of the theory, construct the vertex operators, and compute three and four point amplitudes of twisted and untwisted states. We introduce a background of D-branes, and compute twist states correlators.