arXiv subjects

E. Gava

Publications and source records attributed to E. Gava.

23 records · Page 2Linked to original sources

arXiv1994

Effective Mu-Term in Superstring Theory

In four-dimensional compactifications of the heterotic superstring theory the Kähler potential has a form which generically induces a superpotential mass term for Higgs particles once supersymmetry is broken at low energies. This ``$μ$-term'' is analyzed in a model-independent way at the tree level and in the one-loop approximation, and explicit expressions are obtained for orbifold compactifications. Additional contributions which arise in the case of supersymmetry breaking induced by gaugino condensation are also discussed.

hep-th↗

arXiv1993

Topological Amplitudes in String Theory

We show that certain type II string amplitudes at genus $g$ are given by the topological partition function $F_g$ discussed recently by Bershadsky, Cecotti, Ooguri and Vafa. These amplitudes give rise to a term in the four-dimensional effective action of the form $\sum_g F_g W^{2g}$, where $W$ is the chiral superfield of $N=2$ supergravitational multiplet. The holomorphic anomaly of $F_g$ is related to non-localities of the effective action due to the propagation of massless states. This result generalizes the holomorphic anomaly of the one loop case which is known to lead to non-harmonic gravitational couplings.

hep-th↗

arXiv1992

Superstring Threshold Corrections to Yukawa Couplings

A general method of computing string corrections to the Kähler metric and Yukawa couplings is developed at the one-loop level for a general compactification of the heterotic superstring theory. It also provides a direct determination of the so-called Green-Schwarz term. The matter metric has an infrared divergent part which reproduces the field-theoretical anomalous dimensions, and a moduli-dependent part which gives rise to threshold corrections in the physical Yukawa couplings. Explicit expressions are derived for symmetric orbifold compactifications.

hep-th↗

arXiv1992

Moduli Corrections to Gauge and Gravitational Couplings in four dimensional Superstrings

We study one-loop, moduli-dependent corrections to gauge and gravitational couplings in supersymmetric vacua of the heterotic string. By exploiting their relation to the integrability condition for the associated CP-odd couplings, we derive general expressions for them, both for $(2,2)$ and $(2,0)$ models, in terms of tree level four-point functions in the internal $N=2$ superconformal theory. The $(2,2)$ case, in particular symmetric orbifolds, is discussed in detail.

hep-th↗

arXiv1992

Moduli Corrections to Gravitational Couplings from String loops

We study moduli dependent threshold corrections to gravitational couplings in the case of the heterotic string compactified on a symmetric orbifold, for untwisted moduli, extending previous analysis on gauge couplings. Like in the gauge case, the contribution comes entirely from the spacetime $N=2$ sector. As a byproduct, this calculation provides a simple derivation of the trace anomaly coefficients for the different fields coupled to gravity.

hep-th↗